# Pinholes



## Pinnacle

Hey everyone just a quick question maybe get some thoughts on this one. I have a customer its a 5 year old 4 story retirement home. They keep getting pinholes in the 3/4 copper recirc line. they range from the basement all the way up to the h/w/ts on the roof. Its type L copper so im sure its not the grade. any thoughts would be appreciated.


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## Titan Plumbing

Tagged...


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## deerslayer

Velocity, turbulence, water qaulity, poor design, poor install. Can be all of the above hard to say with the info we have!


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## SlickRick

Happens all the time on recirc. lines, I don't think anyone really knows the answer.


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## Pinnacle

yes sorry i should have searched that topic. its government run so im sure a repipe in wirsbo is out of the question i guess well be doing spot repairs for years to come lol thanks for the response.


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## user7551

Cut out three of any fittings in the recirc system and see if the pipe has been reamed. Because a lot times it goes back to the turbulence in the line from the pipe not being reamed.


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## 89plumbum

Pin holes?????

Check this thread out. Gotta lot of good info. But like Rick said, in the end, I dont think anyone knows for sure.


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## GrumpyPlumber

SlickRick said:


> Happens all the time on recirc. lines, I don't think anyone really knows the answer.


Combination of constant turbulence/heat & O2 = wear/tear, and the fact that W/H's bring out the worst in galvanic reaction & oxidation in a potable system, unlike a closed hydronic system.


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## SlickRick

89plumbum said:


> Pin holes?????
> 
> Check this thread out. Gotta lot of good info. But like Rick said, in the end, I dont think anyone knows for sure.


I called 2 different mech engineers in our area, they couldn't come up with an explanation. We had a dialysis center that was calling once a month, and I wanted to know so I could prevent it in the future, but no solution.


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## SlickRick

GrumpyPlumber said:


> Combination of constant turbulence/heat & O2 = wear/tear, and the fact that W/H's bring out the worst in galvanic reaction & oxidation in a potable system, unlike a closed hydronic system.


I started to say to put this in the political thread, and he would get the same answers.


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## GrumpyPlumber

SlickRick said:


> I started to say to put this in the political thread, and he would get the same answers.


If TX has the same reg's for engineers cert as it's teachers, call an engineer from another state.

I have to ask, did your engineers at least speculate on the combo I mentioned?


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## SlickRick

GrumpyPlumber said:


> If TX has the same reg's for engineers cert as it's teachers, call an engineer from another state.


You posted the answer, back it up with facts from some genius in your state.

Your always going to have some answer, or make it sound good anyway. :laughing:


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## pilot light

SlickRick said:


> Happens all the time on recirc. lines, I don't think anyone really knows the answer.


I do have a theroy.1. A recirc line usually has too big a pump.2. A recirc line then usually has more flow then it needs. 3.It is hot water so the effects of corrosion increase. 4.The pipe is usually too small for the application. 5 When repairs are made we patch it instead of looking at all the issues so the next fitting fails.6. Due diligence.


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## GrumpyPlumber

Rick, really?



SlickRick said:


> *Happens all the time on recirc. lines,* I don't think anyone really knows the answer.


A copper line, subjected to more abuse than a hydronic line gets, with the added beating of an open system's oxidation brings as well as the constant introduction to electrolytic minerals (especially in hard water), and it's a "mystery" as to why recirc lines develop pinholes more frequently that the rest of a potable system?


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## SlickRick

pilot light said:


> I do have a theroy.1. A recirc line usually has too big a pump.2. A recirc line then usually has more flow then it needs. 3.It is hot water so the effects of corrosion increase. 4.The pipe is usually too small for the application. 5 When repairs are made we patch it instead of looking at all the issues so the next fitting fails.6. Due diligence.


A recirc. line is just a continuation of the hw supply. why is it not affecting the lines up stream?


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## SlickRick

GrumpyPlumber said:


> Rick, really?
> 
> 
> 
> A copper line, subjected to more abuse than a hydronic line gets, with the added beating of an open system's oxidation brings as well as the constant introduction to electrolytic minerals (especially in hard water), and it's a "mystery" as to why recirc lines develop pinholes more frequently that the rest of a potable system?


More mumbo jumbo, really.


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## GrumpyPlumber

SlickRick said:


> A recirc. line is just a continuation of the hw supply. why is it not affecting the lines up stream?


It's smaller, a recirc services a larger potable hot line, the ratio of internal surface area to cubic volume is much greater.


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## GrumpyPlumber

SlickRick said:


> More mumbo jumbo, really.


I see.


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## pilot light

SlickRick said:


> A recirc. line is just a continuation of the hw supply. why is it not affecting the lines up stream?


 The re circ pump I think is usually too big! Its under pressure so it is just has to draw back hot water, no need to pull! I think it is all 6 plus maybe more thoughts.i It is usually is littered with fittings, sharkbites compressions and bad solder joints too! It is a kind of a restriction on a a hot water system like a bypassing small vein which is always working! Bigger recirc lines!


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## Titan Plumbing

GrumpyPlumber said:


> It's smaller, a recirc services a larger potable hot line, the ratio of internal surface area to cubic volume is much greater.


I don't get it, most circ lines around here are 3/4", whether that's right or wrong, that is what they is.


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## pilot light

Titan Plumbing said:


> I don't get it, most circ lines around here are 3/4", whether that's right or wrong, that is what they is.


 I think eventually when pressure doubles flow increase 4 times !


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## GrumpyPlumber

Titan Plumbing said:


> I don't get it, most circ lines around here are 3/4", whether that's right or wrong, that is what they is.


Aaaah, so in TX a 3/4" H/W main will have a 3/4" recirc?

Here, the recirc's are 1/2", required on any H/W with a developed length over 100'.

Either way, I can guarantee the recirc is wearing for the reasons I stated, as for why it's only the recirc side, I'd wager TX water is harder than here and the pump itself being on the recirc side acts as an anode.

I'm sure you've seen your share of copper lines after a few years that are in contact with something as small as a d-wall screw, it eats quite a way down the length.

Hopefully no one is offended if I try to play "genius" here.


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## rjbphd

Pinnacle said:


> Hey everyone just a quick question maybe get some thoughts on this one. I have a customer its a 5 year old 4 story retirement home. They keep getting pinholes in the 3/4 copper recirc line. they range from the basement all the way up to the h/w/ts on the roof. Its type L copper so im sure its not the grade. any thoughts would be appreciated.


 Tell us what brand and model pump you have on the system... most likely its oversized. Those zealous bldg engineer missed the concept of hot water return line.. all you need is to keep the hot at the furtherest point of the system, not bringing the max temp at the return at the heater. Which is why I avoid using pump on properly installed hot water return setup. 
All the pump needs to do is to overcome the resistance in the return only from the FURTHEREST point to heater, not the whole system.


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## rjbphd

Titan Plumbing said:


> I don't get it, most circ lines around here are 3/4", whether that's right or wrong, that is what they is.


 I have used 3/8 tubing on return without using the pump, no problem.


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## pilot light

rjbphd said:


> Tell us what brand and model pump you have on the system... most likely its oversized. Those zealous bldg engineer missed the concept of hot water return line.. all you need is to keep the hot at the furtherest point of the system, not bringing the max temp at the return at the heater. Which is why I avoid using pump on properly installed hot water return setup.
> All the pump needs to do is to overcome the resistance in the return only from the FURTHEREST point to heater, not the whole system.


 I agree! :yes:


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## Pinnacle

the pump is a 1/4 hp


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## Pinnacle

31 suites 4 fixture units 3 kitchens and laundry room 4 story 3 hwt on rooftop


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## GrumpyPlumber

rjbphd said:


> I have used 3/8 tubing on return without using the pump, no problem.


Ours is min 1/2", but I like that for the fact that a smaller line contains less H/W - less heat lost, more efficient.

I also branch H/W lines on new construction & remods with this in mind, smaller lines get the water there faster.


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## GrumpyPlumber

Pinnacle said:


> 31 suites 4 fixture units 3 kitchens and laundry room 4 story 3 hwt on rooftop


The H/W main is definitely larger than 3/4".

Another potential problem comes to mind, brass flanges vs CI would reduce electrolysis.


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## pilot light

Pinnacle said:


> the pump is a 1/4 hp


 Too big!


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## Pinnacle

what size pump do you suggest?


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## Pinnacle

the amount of fixtures and size of the building i thought 1/4 hp was perfect but i may be wrong ive never run into this situation before :S


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## hanksplumbing

Pinnacle said:


> Hey everyone just a quick question maybe get some thoughts on this one. I have a customer its a 5 year old 4 story retirement home. They keep getting pinholes in the 3/4 copper recirc line. they range from the basement all the way up to the h/w/ts on the roof. Its type L copper so im sure its not the grade. any thoughts would be appreciated.


the best thing i could suggest is set up a timer on the line , to cut back on the usage , the last time i read the spec's for wirsbo and super pex they did not recommend running a 24hour recirc line , granted that was a year or two ago but i doubt that is has changed .


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## pilot light

Pinnacle said:


> what size pump do you suggest?


 SSF 22. 1/25 hp bell and gossett!


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## pilot light

hanksplumbing said:


> the best thing i could suggest is set up a timer on the line , to cut back on the usage , the last time i read the spec's for wirsbo and super pex they did not recommend running a 24hour recirc line , granted that was a year or two ago but i doubt that is has changed .


 Another great idea!


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## rjbphd

Pinnacle said:


> the pump is a 1/4 hp


 Too frigging oversized!! I used to use a 1/12hp B/G three piece bronze circ pump for 48 units condo! 
Get a bronze or stainless steel 3 speed Wilco pump and set it at 1... maybe 2 .. if needed, rarely 3,if so still better than the pumping monster you have there. 
However, the pinholes problem will be there as the damage is already done but not as frequent.


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## pilot light

pilot light said:


> SSF 22. 1/25 hp bell and gossett!


 Thats maybe too much too!


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## user4

Pinnacle said:


> the pump is a 1/4 hp


I've put pumps that size on 25 story buildings, to install that on a system as small as what you are dealing with is overkill to say the very least. Does it at least have an aquastat and a flowsensor set up so that you are not pumping constantly?


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## rjbphd

hanksplumbing said:


> the best thing i could suggest is set up a timer on the line , to cut back on the usage , the last time i read the spec's for wirsbo and super pex they did not recommend running a 24hour recirc line , granted that was a year or two ago but i doubt that is has changed .


 I threw out the timer crap as the unit needs to be reset often and doesn't know the peak demads with too many tenants bathing and doing laundry together at inhouse laurdny matt.


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## GrumpyPlumber

Killertoiletspider said:


> ....Does it at least have an aquastat and a flowsensor set up so that you are not pumping constantly?


The answer to this changes everything.


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## Titan Plumbing

GrumpyPlumber said:


> It's smaller, a recirc services a larger potable hot line, the ratio of internal surface area to cubic volume is much greater.





Titan Plumbing said:


> I don't get it, most circ lines around here are 3/4", whether that's right or wrong, that is what they is.





GrumpyPlumber said:


> Aaaah, so in TX a 3/4" H/W main will have a 3/4" recirc?
> 
> Here, the recirc's are 1/2", required on any H/W with a developed length over 100'.
> 
> Either way, I can guarantee the recirc is wearing for the reasons I stated, as for why it's only the recirc side, I'd wager TX water is harder than here and the pump itself being on the recirc side acts as an anode.
> 
> I'm sure you've seen your share of copper lines after a few years that are in contact with something as small as a d-wall screw, it eats quite a way down the length.
> 
> Hopefully no one is offended if I try to play "genius" here.


Okay, I'll bite...but I have one question. Since this is true, why doesn't EVERY recirc system develop pinholes.


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## Pinnacle

Killertoiletspider said:


> I've put pumps that size on 25 story buildings, to install that on a system as small as what you are dealing with is overkill to say the very least. Does it at least have an aquastat and a flowsensor set up so that you are not pumping constantly?


Thats another thing i was going to mention. Supposedly there were 2 plumbing contractors on that job 1 had started and got fired and the other finished the job. Theres no aquastat or flowsensor installed. Im going to do some research on some more pumps less hp and definately install the aquastat and flowsensor.


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## GrumpyPlumber

Titan Plumbing said:


> Okay, I'll bite...but I have one question. Since this is true, why doesn't EVERY recirc system develop pinholes.


You're asking the wrong guy - 



SlickRick said:


> Happens all the time on recirc. lines, I don't think anyone really knows the answer.


I see more wear on recirc's, specifically close to the W/H, but it's not some kinda pin-hole epidemic where I am....I also speculated above that maybe TX just has harder water than we do.


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## pilot light

Pinnacle said:


> Thats another thing i was going to mention. Supposedly there were 2 plumbing contractors on that job 1 had started and got fired and the other finished the job. Theres no aquastat or flowsensor installed. Im going to do some research on some more pumps less hp and definately install the aquastat and flowsensor.


 Like a johnson control and a stat? Good call!


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## GrumpyPlumber

Pinnacle said:


> .... definately install the aquastat and flowsensor.


Definitely.

Look @ Grundfos, they have built in timer & stats.


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## rjbphd

Pinnacle said:


> Thats another thing i was going to mention. Supposedly there were 2 plumbing contractors on that job 1 had started and got fired and the other finished the job. Theres no aquastat or flowsensor installed. Im going to do some research on some more pumps less hp and definately install the aquastat and flowsensor.


 Find and befriend a reputable HYDRONIC heating company, not forced hot air company, they are much more knowledgeable in pumping requirement. 
When I was younger, I thought bigger is better til I brought and read Dan Holohan's books... he nailed it for us less engineering minds.


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## rjbphd

GrumpyPlumber said:


> Definitely.
> 
> Look @ Grundfos, they have built in timer & stats.


 Hell no.... okay for me as I keep throwing them away due to customer complains..


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## rjbphd

GrumpyPlumber said:


> You're asking the wrong guy -
> 
> I see more wear on recirc's, specifically close to the W/H, but it's not some kinda pin-hole epidemic where I am....I also speculated above that maybe TX just has harder water than we do.


 Two things... mainly the pump is oversized... 2nd.. if corrisive suplfer in water, will eat out copper pipes, low flo pump will solve the problem.


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## Pinnacle

rjbphd said:


> Find and befriend a reputable HYDRONIC heating company, not forced hot air company, they are much more knowledgeable in pumping requirement.
> When I was younger, I thought bigger is better til I brought and read Dan Holohan's books... he nailed it for us less engineering minds.


 
once again thanks for his name and books im ordering them shortly!


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## pilot light

rjbphd said:


> Find and befriend a reputable HYDRONIC heating company, not forced hot air company, they are much more knowledgeable in pumping requirement.
> When I was younger, I thought bigger is better til I brought and read Dan Holohan's books... he nailed it for us less engineering minds.


 Exactally those forced air guys blow hot air alot! lol taco 005 ? specs?


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## GrumpyPlumber

rjbphd said:


> Two things... mainly the pump is oversized... 2nd.. if corrisive suplfer in water, will eat out copper pipes, low flo pump will solve the problem.


I say stat/timer are the bigger problem, but the pinholes keep bringing me back to the probability that it's either galvanic (touching white metal somewhere) or, as you note, it's the water itself.

On Grundfos, how long you been having the problem?


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## rjbphd

Pinnacle said:


> once again thanks for his name and books im ordering them shortly!


I think he wrote at least 15 books and in ur case, " Pumping Away". Doesn't say much about return line but it will make you grasp the idea of how much pumping is too much. 
You can get packing deal with varoius books with it.


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## Pinnacle

grundfos 1/25


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## rjbphd

GrumpyPlumber said:


> I say stat/timer are the bigger problem, but the pinholes keep bringing me back to the probability that it's either galvanic (touching white metal somewhere) or, as you note, it's the water itself.
> 
> On Grundfos, how long you been having the problem?/QUOTE]
> 
> On the Grundfos, its over sized, the newer one are much smaller and less flow.. with the aquastat, always removed from the apt/condo bulding.. too many tenants have different life styles. Best to use the 3 speed pump and set it accordling.
> Now with the galvanic situtaion, many I've seen they have the electric grounding to the pump,system will hasten the problem.


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## ZL700

Grumpy is spot on with all his diagnosis possibilities. The ultimate cause is excessive velocity.

Pumps are not selected by how many floors the building has, that made me laugh hard thanks whoever posted that. It's not a pump but a circulator in a semi closed system, what goes up also comes down thus equal. Circulators only move water in systems by overcoming friction.


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## GrumpyPlumber

rjbphd said:


> GrumpyPlumber said:
> 
> 
> 
> On the Grundfos, its over sized, the newer one are much smaller and less flow.. with the aquastat, always removed from the apt/condo bulding.. too many tenants have different life styles. Best to use the 3 speed pump and set it accordling.
> Now with the galvanic situtaion, many I've seen they have the electric grounding to the pump,system will hasten the problem.
> 
> 
> 
> After only four years he's getting pinholes, it just seems too soon to be physical wear and tear alone, this is why I immediately went to questioning the possibility of galvanic trouble.... or water Q.
> 
> Maybe Killer can chime in here - he has extensive experience with mutli-resi dwellings.
Click to expand...


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## GrumpyPlumber

ZL700 said:


> Grumpy is spot on with all his diagnosis possibilities. The ultimate cause is excessive velocity.
> 
> Pumps are not selected by how many floors the building has, that made me laugh hard thanks whoever posted that. It's not a pump but a circulator in a semi closed system, what goes up also comes down thus equal. Circulators only move water in systems by overcoming friction.


If you've read the full thread, you're aware that you've been promoted to "token genius".

I do heat, knowing that a circ isn't a pump is essential.


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## Titan Plumbing

ZL700 said:


> Grumpy is spot on with all his diagnosis possibilities. The ultimate cause is excessive velocity.
> 
> Pumps are not selected by how many floors the building has, that made me laugh hard thanks whoever posted that. It's not a pump but a circulator in a semi closed system, what goes up also comes down thus equal. Circulators only move water in systems by overcoming friction.


But why in most cases do we see the pinholes in the section of pipe between the last fixture and the pump?


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## pilot light

rjbphd said:


> I think he wrote at least 15 books and in ur case, " Pumping Away". Doesn't say much about return line but it will make you grasp the idea of how much pumping is too much.
> You can get packing deal with varoius books with it.


 Recirc lines are always kind of warm water not hot or cold! Think a night setback is good depending on the demographic. Myself recirc starts up about 4:45 am Good @ 5 and with the roosters perfect! At 6am it shuts off comes on @ 5 till 7 pm For dinner ! On weekends she gets free reign laundry etc. sunday @ 9 see goes back too weekday settings! :thumbup:


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## rjbphd

ZL700 said:


> Grumpy is spot on with all his diagnosis possibilities. The ultimate cause is excessive velocity.
> 
> Pumps are not selected by how many floors the building has, that made me laugh hard thanks whoever posted that. It's not a pump but a circulator in a semi closed system, what goes up also comes down thus equal. Circulators only move water in systems by overcoming friction.


 That's what I've been saying in the begining of this thread!!... coming from a PhD* guy.


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## GrumpyPlumber

Titan Plumbing said:


> But why in most cases do we see the pinholes in the section of pipe between the last fixture and the pump?


Full circle to my point that it's probably aided by galvanic reaction to the circ itself or the flanges.


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## ZL700

Titan Plumbing said:


> But why in most cases do we see the pinholes in the section of pipe between the last fixture and the pump?


Usually the smallest I.D. Pipe in the whole system and the highest turbulence is found at the suction side of the circulator contributing to the velocity via linear flow in pipe.


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## Titan Plumbing

GrumpyPlumber said:


> Full circle to my point that it's probably aided by galvanic reaction to the circ itself or the flanges.


But, how can that be with a bronze body pump? You don't see galvanic reaction occur on drop ear 90's. Plus the pump has rubber gaskets in most cases.


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## Titan Plumbing

ZL700 said:


> Usually the smallest I.D. Pipe in the whole system and the highest turbulence is found at the suction side of the circulator contributing to the velocity via linear flow in pipe.


Okay, I see that, but around here the circ line is 3/4" for the most part, so out goes that theory.

I asked this before, if this is the real reason, why doesn't every circ system have failures with pinholes?


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## GrumpyPlumber

rjbphd said:


> That's what I've been saying in the begining of this thread!!... coming from a PhD* guy.


He's saying (unless I'm wrong) that circ size isn't the primary problem....they don't "push" in the same way a pump does.

He's referencing my mention of the smaller recirc size, internal surface area to cubic volume (velocity against internal surface) on the question on why the potabale H/W doesn't decay as badly.

I won't debate an over sized pump could cause excessive wear, but as soon Pinnacle said there were no stat or timer, I say start there, but also, look for a cause of electrolysis, that's almost a guaranteed cause in just 4 years.


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## rjbphd

Titan Plumbing said:


> But, how can that be with a bronze body pump? You don't see galvanic reaction occur on drop ear 90's. Plus the pump has rubber gaskets in most cases.


Rubber gaskets don't mean shoit on galvanic problems, the bolts will carry it over.. look at die-electric unoins, that's a whole different thread..


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## GrumpyPlumber

Titan Plumbing said:


> Okay, I see that, but around here the circ line is 3/4" for the most part, so out goes that theory.
> 
> I asked this before, if this is the real reason, why doesn't every circ system have failures with pinholes?


Titan, pay attention in class!

The building is a four story multi-residential, there's no possible way the H/W main is 3/4".


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## Titan Plumbing

GrumpyPlumber said:


> Titan, pay attention in class!
> 
> The building is a four story multi-residential, there's no possible way the H/W main is 3/4".


Hey dipshiot, I'm asking a question...My question pertains to pinholes in a circ system.


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## ZL700

Titan Plumbing said:


> Okay, I see that, but around here the circ line is 3/4" for the most part, so out goes that theory.
> 
> I asked this before, if this is the real reason, why doesn't every circ system have failures with pinholes?


No as temps go up velocity must be maintained at a lower rate due to its increased abrasiveness. So on 3/4" copper pipe with a temp of 140 degrees, 5 GPM shouldnt be exceeded which is about 7 f.p.s. velocity. You shouldn't be surprised how big they oversize these on these 1-1/2" to 3" lines to travel that last distance in a 3/4" copper. 

The real reason is not all systems have oversized circs, kudos to the designers of some of these systems. 

The bigger pump the better? NOT


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## Titan Plumbing

rjbphd said:


> Rubber gaskets don't mean shoit on galvanic problems, the bolts will carry it over.. look at die-electric unoins, that's a whole different thread..


This I can agree on.


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## pilot light

GrumpyPlumber said:


> Titan, pay attention in class!
> 
> The building is a four story multi-residential, there's no possible way the H/W main is 3/4".


 Lets recap then,our findings? :whistling2:


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## rjbphd

GrumpyPlumber said:


> He's saying (unless I'm wrong) that circ size isn't the primary problem....they don't "push" in the same way a pump does.
> 
> He's referencing my mention of the smaller recirc size, internal surface area to cubic volume (velocity against internal surface) on the question on why the potabale H/W doesn't decay as badly.
> 
> (I think)
> 
> I won't debate an over sized pump could cause excessive wear, but as soon a Pinnacle said there were no stat or timer, I say start there, but also, look for a cause of electrolysis, that's almost a guaranteed cause in just 4 years.


Grumpy, I'm saying the main reason for pinholes is due to the over zealous building engineers is from having the pump(s) installed the way oversized for NPSH on suction side, hence, velocity problems. Other factors I've seen is piping iron pipes and fittings from bronze pump into heater will hastens the galvanic
problem too.


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## rjbphd

Titan Plumbing said:


> This I can agree on.


Yea! This call for another beer...


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## pilot light

:whistling2:


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## GrumpyPlumber

Titan Plumbing said:


> Hey dipshiot, I'm asking a question...My question pertains to pinholes in a circ system.


Look, Tit, your objection to my original point was that the 3/4" recirc wasn't smaller than the H/W line...which would debunk my point that greater volume of fluid passes through the smaller recirc than the larger H/W line, at which point I think Rick announced I was "making stuff up".

The point is that whatever the cause of decay/corrosion, it would be accelerated on the recirc side by the greater volume of fluid to internal surface area of the smaller pipe, as ZL700 states in terms of velocity.

Either you accept this, or I'm gonna post a video of Milton Friedman explaining it.


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## Pinnacle

its a 2" main no electrolysis as i can tell but who knows whats behind walls. 3/4 circ line and most pinholes are at the 90s but also in runs on the 4th floor and in the basement.


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## Pinnacle

GrumpyPlumber said:


> Look, Tit, you're objection to my original point was that the 3/4" recirc wasn't smaller than the H/W line...which would debunk my point that greater volume of fluid passes through the smaller recirc than the larger H/W/ line, at which point I think Rick announced I was "making stuff up".
> 
> The point is that whatever the cause of decay/corrosion, it would be accelerated on the recirc side by the greater volume of fluid to internal surface area of the smaller pipe, as ZL700 states in terms of velocity.
> 
> Either you accept this, or I'm gonna post a video of Milton Friedman explaining it.


 
rofl....."tit" hahaha


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## Pinnacle

im going to change the pump within the next week or so.


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## rjbphd

ZL700 said:


> No as temps go up velocity must be maintained at a lower rate due to its increased abrasiveness. So on 3/4" copper pipe with a temp of 140 degrees, 5 GPM shouldnt be exceeded which is about 7 f.p.s. velocity. You shouldn't be surprised how big they oversize these on these 1-1/2" to 3" lines to travel that last distance in a 3/4" copper.
> 
> The real reason is not all systems have oversized circs, kudos to the designers of some of these systems.
> 
> The bigger pump the better? NOT


 Many times, when I see a fairly new pump on system, customers can't justify buying smaller pump again with chroic pinhole problems, I replaced the suction end of pipe with a much larger pipe and flange to meet the minimum NPNS for reduced velocity flow. Think hydronics boys ...


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## GrumpyPlumber

rjbphd said:


> Grumpy, I'm saying the main reason for pinholes is due to the over zealous building engineers is from having the pump(s) installed the way oversized for NPSH on suction side, hence, velocity problems. Other factors I've seen is piping iron pipes and fittings from bronze pump into heater will hastens the galvanic
> problem too.


 A recirc doesn't "pump" it encourages flow, again, I won't debate the possiility that an oversized pump will contribute to the problem, I can't see even a pump causing pinholes after just 4 years, this sounds more like either water Q or electrolysis.galvanic.

And, I know I'm butting heads with Killer...one plumber I seldom do.


----------



## user4

ZL700 said:


> Grumpy is spot on with all his diagnosis possibilities. The ultimate cause is excessive velocity.
> 
> Pumps are not selected by how many floors the building has, that made me laugh hard thanks whoever posted that. It's not a pump but a circulator in a semi closed system, what goes up also comes down thus equal. Circulators only move water in systems by overcoming friction.


If the pump is in the sub basement you need something strong enough to get it to the penthouse, you control the velocity on the way back down, just like the cold water supply.


----------



## rjbphd

rjbphd said:


> Many times, when I see a fairly new pump on system, customers can't justify buying smaller pump again with chroic pinhole problems, I replaced the suction end of pipe with a much larger pipe and flange to meet the minimum NPNS for reduced velocity flow. Think hydronics boys ...


 And girls ( sorry PinkPlumber)


----------



## Pinnacle

rjbphd said:


> And girls ( sorry PinkPlumber)


im a hydronic noob you know that  im learning slowly but surely.


----------



## pilot light

Wow not bad at all maestro! :thumbup:


----------



## Pinnacle

Killertoiletspider said:


> If the pump is in the sub basement you need something strong enough to get it to the penthouse, you control the velocity on the way back down, just like the cold water supply.


pump is in the mechanical room on the roof above the hwts


----------



## GrumpyPlumber

Killertoiletspider said:


> If the pump is in the sub basement you need something strong enough to get it to the penthouse, you control the velocity on the way back down, just like the cold water supply.


He's talking relative velocity between recirc and Main, explaining the pinholes in recirc only.


----------



## rjbphd

Killertoiletspider said:


> If the pump is in the sub basement you need something strong enough to get it to the penthouse, you control the velocity on the way back down, just like the cold water supply.


Wrong, wrong... heater(s) location doesn't mean shoit when it come to circ water in the system.. all you need to just to move the water from the FURTHEREST hot water fixtures back to heater not the whole system as stated before.


----------



## rjbphd

Pinnacle said:


> pump is in the mechanical room on the roof above the hwts


 Doesn't matter where the heaters are... think of this... the recirc system is a ferris wheel... where the motor(pump)???
Not in the chair.. its in the middle'center' of the ferris wheel.. donsnt matter what pressure you are at the top or bottom, 
Those Dan Holohan's books will educate you more than me.


----------



## user4

rjbphd said:


> Wrong, wrong... heater(s) location doesn't mean shoit when it come to circ water in the system.. all you need to just to move the water from the FURTHEREST hot water fixtures back to heater not the whole system as stated before.


The furthest fixture is 27 floors below the water heater.


----------



## GrumpyPlumber

Killertoiletspider said:


> The furthest fixture is 27 floors below the water heater.


Why does this change anything?


----------



## rjbphd

Killertoiletspider said:


> The furthest fixture is 27 floors below the water heater.


Then u'll just need enough to get the water to flow from 27 floors below.. so in that case how big is the return and pump? 
I admitted it too large of my scope, but the same principle stills apply.


----------



## pilot light

You know whats stop pinholes a larger nail! Its all good until the nail gives up. Did i just nail it? lol! :jester:


----------



## user4

GrumpyPlumber said:


> Why does this change anything?


You have to size the recirc pump to lift 300 feet straight up without a complete heat loss.


----------



## rjbphd

Where did Pinncale go? Went out to Bethpage, Long Island to buy those books???


----------



## GrumpyPlumber

Killertoiletspider said:


> You have to size the recirc pump to lift 300 feet straight up without a complete heat loss.


The circ doesn't do the lifting, water's already there, circ encourages movement.


----------



## user4

GrumpyPlumber said:


> The circ doesn't do the lifting, water's already there, circ encourages movement.


The water heater is on the top floor, you have to get the recirc water back up to it, three hundred feet up, around here high rises are piped from the top down.


----------



## rjbphd

Killertoiletspider said:


> You have to size the recirc pump to lift 300 feet straight up without a complete heat loss.


If the system already pressurized, the circ pump does NOT "lift" !! It just moves the water by creating the differential pressure on each side of pump..


----------



## rjbphd

Killertoiletspider said:


> The water heater is on the top floor, you have to get the recirc water back up to it, three hundred feet up, around here high rises are piped from the top down.


 Okay, on the same building.. does it have hydronic heat?


----------



## GrumpyPlumber

Killertoiletspider said:


> The water heater is on the top floor, you have to get the recirc water back up to it, three hundred feet up, around here high rises are piped from the top down.


Not If you bleed the line.


----------



## GrumpyPlumber

rjbphd said:


> Okay, on the same building.. does it have hydronic heat?


Ya beat me to the punch, but I have a feeling he's gonna make us look like schmucks.


----------



## rjbphd

GrumpyPlumber said:


> Ya beat me to the punch, but I have a feeling he's gonna make us look like schmucks.


A mind is like a parachute, only works when its opened...


----------



## GrumpyPlumber

rjbphd said:


> A mind is like a parachute, only works when its opened...


Well, this "parachute's" getting ready fer bed.


----------



## user4

rjbphd said:


> If the system already pressurized, the circ pump does NOT "lift" !! It just moves the water by creating the differential pressure on each side of pump..


The circ pump has to lift it, you are controlling the velocity every five floors with pressure reducing valves on the way back down, so that the water is at the same pressure on the bottom as it is on the top. If you don't you would have water pressures in excess of a hundred PSI on the lower floors, you do have to deal with gravity, remember, it sucks.


----------



## rjbphd

Killertoiletspider said:


> The circ pump has to lift it, you are controlling the velocity every five floors with pressure reducing valves on the way back down, so that the water is at the same pressure on the bottom as it is on the top. If you don't you would have water pressures in excess of a hundred PSI on the lower floors, you do have to deal with gravity, remember, it sucks.


That make sense... now as I'm not a high rise PhD*... is the hot water re circ pump as large as cold water booster pump to get the "same" pressure up there?


----------



## GrumpyPlumber

rjbphd - I told ya, schmucks!

His livelihood was/is high-rises....we never even thought to factor PRV's, to him it's second nature.


----------



## rjbphd

GrumpyPlumber said:


> rjbphd - I told ya, schmucks!
> 
> His livelihood was/is high-rises....we never even thought to factor PRV's, to him it's second nature.


My parachute is still opened..


----------



## GrumpyPlumber

rjbphd said:


> My parachute is still opened..


Actually, it is....drum roll, please....


----------



## user4

rjbphd said:


> That make sense... now as I'm not a high rise PhD*... is the hot water re circ pump as large as cold water booster pump to get the "same" pressure up there?


No, the pump is nothing like the pumps on the supply side, you and Grumpy have already demonstrated why, you just need to get the water back to the heater without significant heat loss.



GrumpyPlumber said:


> rjbphd - I told ya, schmucks!
> 
> His livelihood was/is high-rises....we never even thought to factor PRV's, to him it's second nature.


I do prefer jobs that involve tower cranes and caissons drilled a thousand feet deep.


----------



## Pinnacle

Thanks alot for all the great info and opinions guys really appreciate it.


----------



## johnlewismcleod

Pinnacle said:


> its a 2" main no electrolysis as i can tell but who knows whats behind walls. 3/4 circ line and most pinholes are at the 90s but also in runs on the 4th floor and in the basement.


High rises are not my area of expertise (if I even have an area of expertise ), but I haven't seen any mention of wye strainers in this thread. 

All valid points so far, but w/o a wye strainer to collect the particulates the abrasive effects would be most pronounced at the 90's and the last section before the pump.

Is there a wye strainer of sufficient mesh to stop abrasion due to particulates?


----------



## user7551

Pinnacle said:


> its a 2" main no electrolysis as i can tell but who knows whats behind walls. 3/4 circ line and most pinholes are at the 90s but also in runs on the 4th floor and in the basement.



So your saying most of the leaks are at the 90's and on the runs on the 4th floor ,by this do you mean couplings . Thats where not reaming the pipe could be causing turbulence and pitting the pipe and then the pinhole leak starts. 

http://www.copper.org/applications/plumbing/techcorner/designing_piping_systems.html


----------



## Pinnacle

playme1979 said:


> So your saying most of the leaks are at the 90's and on the runs on the 4th floor ,by this do you mean couplings . Thats where not reaming the pipe could be causing turbulence and pitting the pipe and then the pinhole leak starts.
> 
> http://www.copper.org/applications/plumbing/techcorner/designing_piping_systems.html


No I mean straight runs on the actual length of pipe


----------



## user7551

Pinnacle said:


> No I mean straight runs on the actual length of pipe



Are the leaks near any couplings.


----------



## rjbphd

Pinnacle said:


> No I mean straight runs on the actual length of pipe


Overpumping and not enough NPSH.. period


----------



## user7551

Copper tube and fittings have a remarkable track record for plumbing use. The ancient Egyptians are known to have used copper pipes for transporting water and, in modern times, copper tube has been used for over 75 years for plumbing in the U.S. It’s a fact that the majority of problems with a copper piping installation can be prevented by proper design and installation practices. It’s also true that a major cause of difficulty is erosion corrosion, a mechanically induced failure, which may be caused by number of conditions: 


*Lack of reaming of the tube ends.*

Burrs left on the inside of the tube can cause interruption of smooth flow resulting in localized high water velocity and cavitation. Immediately downstream of the unreamed tube end local flow pressure will be drastically reduced, allowing air bubbles entrained in the water to escape and scour the tube/fitting wall, creating pits that may eventually cause failure.







Example of Erosion Corrosion

*Water at high velocity.*

An undersized piping system or an oversized recirculating pump may cause high water velocity. Installation of a smaller capacity pump(s) or a throttling bypass on the existing pump(s) should help in lowering the velocity of the water in the system. _The recommended maximum velocity for water in a copper tube system is 5 - 8 feet per second (fps) for cold water systems, 4 - 5 fps for hot water systems < 140º F, and 2-3 fps for hot water systems with a temperature greater than 140º F_.
*Numerous, abrupt changes in direction in the piping system.*

Where structural conditions cause numerous directional changes, long radius (1.5 x Diameter) fittings should be used to minimize the interruption of laminar flow.
*Protrusions into the flow stream.*

These can be caused by excessive lumps of solder/brazing material, improperly fabricated tees (branch protruding into the run pipe), etc. These protrusions can also cause the interruption of smooth flow resulting in localized high water velocity and cavitation.
*Excessive water temperature.*

Heating the water above 140º F can accelerate the process of erosion-corrosion. To avoid "cold" hot water concerns insulation can be added to the hot water supply lines.
*Excessive amounts of dissolved gases, vapors or suspended solids in the water conveyed.*

At high velocities these gases, vapors or solids can impinge on the metal surface causing erosion corrosion.


----------



## user7551

rjbphd said:


> Overpumping and not enough NPSH.. period



I agree with you to a point , the pump is exacerbating underlying problems perhaps like pipe not reamed.


----------



## BROOKLYN\PLUMB

To be honest I have never seen pitting occur at a higher frequency on return lines. The only "severe pitting" (not localized as with burrs) I have witnessed was caused by heavy electrical equipment which was grounding to the copper. The pitting was very uniform and in some cases the tubing become paper thin. 

Ofcourse when it happened at my parents house I was at a total loss it was on the cold main about a 60' ft. Straight run 3/4" L about 35 years old and no heavy equipment.


----------



## Pinnacle

johnlewismcleod said:


> High rises are not my area of expertise (if I even have an area of expertise ), but I haven't seen any mention of wye strainers in this thread.
> 
> All valid points so far, but w/o a wye strainer to collect the particulates the abrasive effects would be most pronounced at the 90's and the last section before the pump.
> 
> Is there a wye strainer of sufficient mesh to stop abrasion due to particulates?


There's no wye strainers that I can see.


----------



## johnlewismcleod

Pinnacle said:


> There's no wye strainers that I can see.


Bingo.

Like Playme and the others have said...it's liikely the result of more than one factor, but I'd get some wye strainers with blow-off valves on there pronto.

Wye strainers are win/win: they stop the particulate from eating away at the piping and once a year or so you get an easy service call when the hot pressure starts to drop. Show up, look very seriously at the boiler and lines, then blow the sediment out of the strainer :thumbsup:


----------



## Pinnacle

So i went to my supplier this afternoon after a couple calls and i picked up a smaller recirc pump with aquastat and flosensor built in amazing little unit. thanks for all the info and help!


----------



## Pinnacle

Grundfos 1/25


----------



## rjbphd

Pinnacle said:


> So i went to my supplier this afternoon after a couple calls and i picked up a smaller recirc pump with aquastat and flosensor built in amazing little unit. thanks for all the info and help!


Dump the aquastat and flo sensor.. put in the 3 speed pump and set accordling.


----------



## Pinnacle

they have a grundfos 3 speed there i was debating on getting that one.


----------



## rjbphd

Pinnacle said:


> they have a grundfos 3 speed there i was debating on getting that one.


Should've got it.. what did you picked up?


----------



## rjbphd

rjbphd said:


> Should've got it.. what did you picked up?


Thought Wilco is a big thing in Canada...


----------



## Pinnacle

rjbphd said:


> Thought Wilco is a big thing in Canada...


Wilo? Grundfos Liberty and Myers are the 3 big ones


----------



## Pinnacle

rjbphd said:


> Should've got it.. what did you picked up?


I picked up what you see in the picture but i had to buy the model that converts it to 3/4" unions i can always return it but i think im going to try it out!


----------



## rjbphd

Pinnacle said:


> I picked up what you see in the picture but i had to buy the model that converts it to 3/4" unions i can always return it but i think im going to try it out!


What picture??? Did someone steal it and posted in Homey Depooty?


----------



## Pinnacle

rjbphd said:


> What picture??? Did someone steal it and posted in Homey Depooty?


lol what the heck it shows its posted i can see it on my end as well in the thread let me try again


----------



## Pinnacle

Can you see this picture? lol


----------



## SlickRick

The other picture is at the top of the page,


----------



## rjbphd

Pinnacle said:


> Can you see this picture? lol


Got it! And JUNK!!! I've love those thing as I'm always replacing them!! They are rebadged of Laing pump .. crapola in my part. Best go with a REAL pump assy. Bronze 3 speed made by Grundfus, B/G, and Wilco which I'm surprised that its not big there, perhaps, you are at a plumbing supply house, not Hydronic supply house where they have those pumps for sure??


----------



## GrumpyPlumber

rjbphd said:


> ..... Best go with a REAL pump assy. Bronze 3 speed made by Grundfus, ....


Yer busted.


----------



## Pinnacle

we have 2 main suppliers the main one is Noble.ca they are plumbing hvac and hydronics and the other is Wolseley which is canadas fergusson. You say Wilco Grumpy says Grundfos lol


----------



## rjbphd

GrumpyPlumber said:


> Yer busted.


Me?? I'm busted??


----------



## GrumpyPlumber

rjbphd said:


> Me?? I'm busted??


Wasn't it you 'said Grundfos were junk?


----------



## rjbphd

GrumpyPlumber said:


> Wasn't it you 'said Grundfos were junk?


 I'm talking about the rebadged "grundfus" made by Liang pump. Just putting a name brand on junk products doent make it good as the parent company.


----------



## pilot light

rjbphd said:


> I'm talking about the rebadged "grundfus" made by Liang pump. Just putting a name brand on junk products doent make it good as the parent company.


 How can you tell the difference? Never heard of liang. South Korean?


----------



## rjbphd

pilot light said:


> How can you tell the difference? Never heard of liang. South Korean?


 Been here in this area for years, floating impeller magent design. Any tiny speck of dirt will stop the impeller but motor will keep on spining and often the check valve is blame for lack of flow. Somehow,grundfus have it now.


----------



## ZL700

Pinnacle said:


> Grundfos 1/25


That is not a Laing circulator but a true grundfos product.

By the way, Laing is a Xylem company which is also the parent of Bell & Gossett, ITT, Hoffman, McDonald Miller, Goulds and a 1/2 dozen others. 

So Xylem wouldnt be making a Laing that Grundfos would buy and resell. Grundfos makes thier own, seen it myself in Kansas and California.


----------



## pilot light

ZL700 said:


> That is not a Laing circulator but a true grundfos product.
> 
> By the way, Laing is a Xylem company which is also the parent of Bell & Gossett, ITT, Hoffman, McDonald Miller, Goulds and a 1/2 dozen others.
> 
> So Xylem wouldnt be making a Laing that Grundfos would buy and resell. Grundfos makes thier own, seen it myself in Kansas and California.


 Different name same product I figured we would come up with this eventually! Now I know the liang!


----------



## ZL700

pilot light said:


> Different name same product I figured we would come up with this eventually! Now I know the liang!


Not really, the Grundfos in the pic is a direct coupled impeller, not like the magnetic Laing. Laing IMO makes some really nice micro circulators often best used in remote coils and fan coil units.

The Grundfos in the pic also has a built in check valve and aquastat making it a nice complete unit.


----------



## pilot light

ZL700 said:


> Not really, the Grundfos in the pic is a direct coupled impeller, not like the magnetic Laing. Laing IMO makes some really nice micro circulators often best used in remote coils and fan coil units.
> 
> The Grundfos in the pic also has a built in check valve and aquastat making it a nice complete unit.


 Yes I have used some on recirc lines!


----------



## brians plumbing

I would check out the water heater If it has an anode rod in it, it could need a new one, the anode rod screws in from the top of the heater and its purpose is to atract the stuff in the water that eats away at the tank and pipe, if it is all eaten up replacing it might help


----------



## brians plumbing

Try replacing the anode rod in the water heater the rod goes int the heater from the top and screws in and it looks like a bolt on top of the heater. its job is to attract all the particles in the water that want to eat the tank and the piping and to eat the rod instead. so if the rod is all eaten up that might help.


----------



## fightnews

SlickRick said:


> I called 2 different mech engineers in our area, they couldn't come up with an explanation. We had a dialysis center that was calling once a month, and I wanted to know so I could prevent it in the future, but no solution.


I bet it has something to do with the pump shutting off and the back surge of water trying to force itself out.

I think a check valve before the pump would stop it.


----------



## SlickRick

fightnews said:


> I bet it has something to do with the pump shutting off and the back surge of water trying to force itself out.
> 
> I think a check valve before the pump would stop it.


Yeah, there are many opinions on this issue.


----------



## fightnews

SlickRick said:


> A recirc. line is just a continuation of the hw supply. why is it not affecting the lines up stream?


I agree, The only thing diffrent is the pump. It has to have something to do with that. It's the only thing it could be.


----------



## fightnews

GrumpyPlumber said:


> It's smaller, a recirc services a larger potable hot line, the ratio of internal surface area to cubic volume is much greater.


all the branches are smaller to, so what?


----------



## johnlewismcleod

fightnews said:


> all the branches are smaller to, so what?


Smaller surface area = more friction

Reduced pipe surface area = greater susceptibility to abrasive and/or electrolysis wear

Wall thickness of 1/2" L copper = 0.040" , wall thickness of 2-1/2" L copper = 0.080"

The drops aren't part of the circulation loop, only the main feed(s) and the return(s).


That's a few "whats" for starters


----------



## GrumpyPlumber

johnlewismcleod said:


> Smaller surface area = more friction
> 
> Reduced pipe surface area = greater susceptibility to abrasive wear


Also, faster rate of O2 and minerals (electrolytes) introduced to the surface.


----------



## fightnews

johnlewismcleod said:


> Smaller surface area = more friction
> 
> Reduced pipe surface area = greater susceptibility to abrasive and/or electrolysis wear
> 
> Wall thickness of 1/2" L copper = 0.040" , wall thickness of 2-1/2" L copper = 0.080"
> 
> The drops aren't part of the circulation loop, only the main feed(s) and the return(s).
> 
> 
> That's a few "whats" for starters


yeah nice wink and everything but again so what. The point was with his explanation there should be pin holes in the smaller branch lines too. 

Next time you want to drop a bunch of meaningless facts in an attempt to "school" someone try brushing up on your reading comprehension skills first.

And what's with calling branches "drops"? Most of the time they rise? Makes no sense.p:


----------



## rjbphd

fightnews said:


> yeah nice wink and everything but again so what. The point was with his explanation there should be pin holes in the smaller branch lines too.
> 
> Next time you want to drop a bunch of meaningless facts in an attempt to "school" someone try brushing up on your reading comprehension skills first.
> 
> And what's with calling branches "drops"? Most of the time they rise? Makes no sense.p:


My posts were meaningless facts????


----------



## GrumpyPlumber

rjbphd said:


> My posts were meaningless facts????


You're Bill Murray, this is Groundhog Day.

He should just go back to the start of the thread.


----------



## fightnews

rjbphd said:


> My posts were meaningless facts????


To the topic yes. Another reason your reading comprehension needs some work.


GrumpyPlumber said:


> You're Bill Murray, this is Groundhog Day.
> 
> He should just go back to the start of the thread.


And you should go back to your bubble.


----------



## rjbphd

fightnews said:


> To the topic yes. Another reason your reading comprehension needs some work.
> 
> And you should go back to your bubble.


So that make you above all?


----------



## fightnews

rjbphd said:


> So that make you above all?


if you say so....


----------



## Adamche

fightnews said:


> if you say so....


Maybe time to put up or shut up... you appear to be very fond of pointing out others faults, and not really in the name of constructive criticism, more like antagonism. So show us some of your stuff,......or do you want to remain anonymous!


----------



## rjbphd

fightnews said:


> if you say so....


 Nobody here like a condescending ( FIB ) like you.


----------



## user7551

fightnews said:


> if you say so....


This is the typical responses of a third year apprentice.


----------



## johnlewismcleod

fightnews said:


> yeah nice wink and everything but again so what. The point was with his explanation there should be pin holes in the smaller branch lines too.
> 
> Next time you want to drop a bunch of meaningless facts in an attempt to "school" someone try brushing up on your reading comprehension skills first.
> 
> And what's with calling branches "drops"? Most of the time they rise? Makes no sense.p:


K...you've clearly got a very limited understanding of hydrodynamics and plumbing, as well as some serious anger/ego issues.


In the future I will do my best to ignore your posts. 

You are a waste of time and effort.


----------



## Adamche

Is the hare winking?


----------



## fightnews

rjbphd said:


> So that make you above all?





rjbphd said:


> Nobody here like a condescending ( FIB ) like you.


Yeah Ok you don't speak for anyone but yourself. I'm not condescending because you say so. You're just mad because I don't agree with you and I pointed out why what you said made no sense. You can dish it out but can't take it.


----------



## GrumpyPlumber

fightnews said:


> Yeah Ok you don't speak for anyone but yourself. ....


No, actually, you can add me to the list.


----------



## fightnews

johnlewismcleod said:


> K...you've clearly got a very limited understanding of hydrodynamics and plumbing, as well as some serious anger/ego issues.
> 
> 
> In the future I will do my best to ignore your posts.
> 
> You are a waste of time and effort.


Wow you sure know a lot about me From a few typed sentences. Please do ignore my posts and never respond to me again. I feel the same way about closed minded people who think they know everything. And there are plenty of them in this business. It's no wonder this trade is in the shape it's in.


----------



## PrecisePlumbing

GrumpyPlumber said:


> No, actually, you can add me to the list.


Put my name down too while your there....

Unfortunately Mr. News, science always wins


----------



## luv2plum

So, just going to throw out a theory here as to one possible reason pinhole leaks occur. I notice that hydronic systems built from copper do not seem be developing pinhole leaks, whereas domestic water recirc systems with comparable velocities do. What if this is what is happening:
- with fresh oxygenated water, copper oxide forms on the pipe's interior surface. 
- turbulent flow, with a slightly higher velocity than ideal (let's say 5 FPS) damages a section of the relatively soft copper oxide layer, exposing bare copper.
- the bare copper combines with oxygen in the water and forms new oxide layer.
- each time a new copper oxide layer is created and torn off, it takes some of the copper with it, creating a pit in the pipe wall, and eventually a pinhole.

In addition, since oxygen molecules that are entrained in the water are released at higher temperatures, it would increase the speed of the development of the oxide layer, which would explain why hot water lines will wear out quicker than cold water lines (if both were exposed to the same velocities and constant flow).

This would also explain why domestic open systems wear out much faster than hydronic systems with equivalent velocities. Maybe the velocities we use are not fast enough to damage the copper itself, but are fast enough to damage the oxide layer.

Is the answer to reduce velocities to the point where they cannot damage the oxide layer? 

Does that make sense?


----------



## acid waste

You need to restrict the flow of the recirc you are flowing entirely too fast they sell a device that we install our recirc line to slow it down instead of pumping 30,000 billion gallons per minute it slows it down to about three or 4 gallons per minute of flow on the line there's a man in San Antonio call Glen Johnson at South Texas heat treat I've worked with him for over 20 years experience working with him is been very educational it might be worth giving him a call he loves to educate also We started using the long radius refrigeration 90s and this helps out in the turbulence greatly also definitely check to see if they reamed the pipe that creates a lot of turbulence that cuts into the fittings

I would rather die on my feet than live on my knees Emiliano Zapata


----------



## justme

acid waste said:


> You need to restrict the flow of the recirc you are flowing entirely too fast they sell a device that we install our recirc line to slow it down instead of pumping 30,000 billion gallons per minute it slows it down to about three or 4 gallons per minute of flow on the line there's a man in San Antonio call Glen Johnson at South Texas heat treat I've worked with him for over 20 years experience working with him is been very educational it might be worth giving him a call he loves to educate also We started using the long radius refrigeration 90s and this helps out in the turbulence greatly also definitely check to see if they reamed the pipe that creates a lot of turbulence that cuts into the fittings
> 
> I would rather die on my feet than live on my knees Emiliano Zapata


You can call glen about filters and a lot of other topics also , he is a very intelligent guy.


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## stupid helper

Do y'all have anyone in Texas that does the Epoxy pipe?


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## johnlewismcleod

I've never used that, but heard of some that do...and also how it fails to adhere uniformly and doesn't measure up to the promises made about the system.

Could be the result of bad install technique, though. I don't know enough about it really to say much on the subject.


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## stupid helper

johnlewismcleod said:


> I've never used that, but heard of some that do...and also how it fails to adhere uniformly and doesn't measure up to the promises made about the system.
> 
> Could be the result of bad install technique, though. I don't know enough about it really to say much on the subject.


If done right its jam up and works great. But there is a lot of different problems that you could run into.


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