# Expansion Tanks - Do we really need em?



## nhmaster3015 (Aug 5, 2008)

Spillover :thumbsup:

Nice job there Red as usual you have em by the short and curlies :laughing:


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## Shadow Sabre (Oct 12, 2009)

Yes, I would say so with the shade tree DIY and the uneducated making changes everywhere I can see the need more and more. Every time you add Backflow protection you better be thinking about thermal expansion or it's going to bite you in the ass.

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## Redwood (Sep 8, 2008)

nhmaster3015 said:


> Nice job there Red as usual you have em by the short and curlies :laughing:


Ah you noticed...
Just having a little fun battling the forces of ignorance...:laughing:

Expansion Tanks are definitely needed on a closed system.
That's my story and I'm sticking to it... :laughing:

Are you still banned over there? :whistling2:
If not join the fun...
We're gonna put out the rubber sheets and pass around a bottle of oil tonite....
The engineers are coming out of the woodwork...


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## beachplumber (Feb 7, 2010)

I have seen many heaters put in without and they are fine, but there are situations that seem to require them. I have found to save me call backs put them in according to code. collect and be happy:thumbup::thumbup:


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## PrecisePlumbing (Jan 31, 2011)

Dunno how relevant it is to you guys but here in oz the only time we use expansion tanks is on radiant heat systems. If an area has hard water we will put an expansion relief valve on the hot water service and drain into same area as the ptr.


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## nhmaster3015 (Aug 5, 2008)

After my last tirade I doubt I will ever be welcome there again. Just couldn't seem to get along with a couple of the unlicensed moderators there :laughing: though Slusser still claims I haunt the place. :whistling2: Still, when it comes to ignorant posts it has to be one of the best sites on the web


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## Radium (Dec 25, 2010)

I've noticed less of a sandwich effect after I installed an expansion tank on an on demand heater with or without a recirc run.


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## plbgbiz (Aug 27, 2010)

PrecisePlumbing said:


> ...If an area has hard water we will put an expansion relief valve on the hot water service...


Hard water contributes to thermal expansion? :blink: I don't get it. PLease explain.


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## Plumber Jim (Jun 19, 2008)

I think anyone who calls themselves a plumber and doesn't understand therma expansion needs to learn then they can answer that question. is said that alot of plumbers don't know the difference between a closed system and an open system.


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## markb (Jun 11, 2009)

In a domestic HWT (140 degrees), water will expand around 25%

Typically, with a 50-60 PSI supply, and using a small to mid sized HWT even when the water expands, the pressure won't really go over 80psi. Therefore, not really and issue on some systems considering the 80 PSI isn't that large of a strain on the plumbing system.

However, one larger systems, it is a different story and requires some calculations.

...or so I say...It's 1:30am...I dunno why I posted at all. You guys should know this...


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## Redwood (Sep 8, 2008)

markb said:


> In a domestic HWT (140 degrees), water will expand around 25%
> 
> Typically, with a 50-60 PSI supply, and using a small to mid sized HWT even when the water expands, the pressure won't really go over 80psi. Therefore, not really and issue on some systems considering the 80 PSI isn't that large of a strain on the plumbing system.
> 
> ...


Are you sure about this? :whistling2:
You realize water does not compress don't you?
Maybe you have never seen a closed system....

Maybe you want to play with this...


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## easttexasplumb (Oct 13, 2010)

plbgbiz said:


> Hard water contributes to thermal expansion? :blink: I don't get it. PLease explain.


 
Well you see the minerals in the hard water will hold heat longer than softer water. The minerals also contain more oxygen causing increase in temperature. Harder water at least since 1905 also contains more pressure than softer water. With all these combined attributes it is obvious how hard water contributes to increased temp and pressure. :laughing:


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## Redwood (Sep 8, 2008)

Wow! This subject could be a good one for someone that wants a good signature line...:laughing:

Come to think of it.... I did get mine from a similar discussion....:thumbup:


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## Shadow Sabre (Oct 12, 2009)

And all those years I thought hard water and minerals contributed to loading up relief valves not allowing tanks to escape built up pressure essentially turning it into a bomb. But, what do I know.;P

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## PrecisePlumbing (Jan 31, 2011)

easttexasplumb said:


> Well you see the minerals in the hard water will hold heat longer than softer water. The minerals also contain more oxygen causing increase in temperature. Harder water at least since 1905 also contains more pressure than softer water. With all these combined attributes it is obvious how hard water contributes to increased temp and pressure. :laughing:


Nail on the head my friend. It's a safegaurd if the ptr scales up and fails. That's the only expansion control we really do and most don't bother but I'm a stickler for getting things right


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## nhmaster3015 (Aug 5, 2008)

anybody ever actually see a relief valve loaded with scale to the point of failure.?


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## 1703 (Jul 21, 2009)

nhmaster3015 said:


> anybody ever actually see a relief valve loaded with scale to the point of failure.?



Yes. only when someone has done something stupid like turn it up side down and it has seeped on and off for years. I haven't seen one scaled bad when installed properly. But so what. Isn't thermal expansion and relief valve scaling/failure two separate issues? 





> I think anyone who calls themselves a plumber and doesn't understand therma expansion needs to learn then they can answer that question. is said that alot of plumbers don't know the difference between a closed system and an open system.


^^amen^^


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## PLUMBER_BILL (Oct 23, 2009)

nhmaster3015 said:


> anybody ever actually see a relief valve loaded with scale to the point of failure.?


'

YES!!

http://www.parrsplumbing.com Explore the water heater blog

click on water heater explosions


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## PrecisePlumbing (Jan 31, 2011)

nhmaster3015 said:


> anybody ever actually see a relief valve loaded with scale to the point of failure.?


Hell yea man Probably every 5th one I pull out. I've got a heap of new ptr's so I sell them off for cheap.


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## markb (Jun 11, 2009)

Redwood said:


> Are you sure about this? :whistling2:
> You realize water does not compress don't you?
> Maybe you have never seen a closed system....
> 
> Maybe you want to play with this...


http://wiki.answers.com/Q/Do_liquids_expand_when_heated

Water does expand. 

The 25% part I read in some manufacturer literature (I believe it was A.O. Smith's guide to designing commercial hot water heating systems).


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## Protech (Sep 22, 2008)

Yes. Prolly have several photos that I don't care to dig up at the moment.



nhmaster3015 said:


> anybody ever actually see a relief valve loaded with scale to the point of failure.?


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## Widdershins (Feb 5, 2011)

nhmaster3015 said:


> anybody ever actually see a relief valve loaded with scale to the point of failure.?


 I see it all the time on installs where the potable water supply comes from a well.


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## easttexasplumb (Oct 13, 2010)

Widdershins said:


> I see it all the time on installs where the potable water supply comes from a well.


I see it alot mostly on old heaters, I take out the T&P valves for the scrap brass.


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## plumber666 (Sep 19, 2010)

markb said:


> http://wiki.answers.com/Q/Do_liquids_expand_when_heated
> 
> Water does expand.
> 
> The 25% part I read in some manufacturer literature (I believe it was A.O. Smith's guide to designing commercial hot water heating systems).


I think that's more like 2.5% Which is a lot in a closed system (BOOM). In a domestic water system, unless there's a backflow preventor on the watermain ( not including PRV's which some still think are backflow preventors) EXP tanks are a waste of time and money. Except for the swindler that sells and installs them.


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## ToUtahNow (Jul 19, 2008)

We went an awful lot of years without expansion tanks. Originally expansion tanks were brought in to address T&Ps spilling due to thermal expansion. There are certain installation where they should be installed.

Mark


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## Widdershins (Feb 5, 2011)

ToUtahNow said:


> We went an awful lot of years without expansion tanks. Originally expansion tanks were brought in to address T&Ps spilling due to thermal expansion. There are certain installation where they should be installed.
> 
> Mark




Most of the counties in my neck of the woods require expansion tanks on all gas fired H/W tanks but not on electric H/W tanks.

The rationale behind this requirement at the time was that gas fired tanks heated more rapidly, dramatically hastening the rate of thermal expansion.

With the advent of rapid recovery electrics, they are now rethinking that rationale -- I imagine the next code revision will require expansion tanks on all H/W tanks.

As for me, I install expansion tanks on all gas fired tanks and on any electric tanks where check valves, pumps, backflow preventers or any other device that closes the system are installed on the system. I will also install an expansion tank on an electric if piping the TPR to an indirect drain or to the outside is impractical or impossible.


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## nhmaster3015 (Aug 5, 2008)

Water is an amazing thing. It does expand, but it won't compress. It can be a solid, a liquid and a vapor. The incompressability of water is why it can be used in water jet machines that will cut 3" of steel like warm butter.


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## Plumber Jim (Jun 19, 2008)

markb said:


> http://wiki.answers.com/Q/Do_liquids_expand_when_heated
> 
> Water does expand.
> 
> The 25% part I read in some manufacturer literature (I believe it was A.O. Smith's guide to designing commercial hot water heating systems).


Red didn't say water doesn't expand. He said that it doesn't compress.


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## Redwood (Sep 8, 2008)

Plumber Jim said:


> Red didn't say water doesn't expand. He said that it doesn't compress.


*Zackly!* :thumbup:

And the link I posted will tell you how much it expands...
Maybe you want to play with this...

Input the water heater size in gallons, supply pressure, expansion tank pre charge (which should match the supply pressure), T&P Valve or, Secondary Relief Valve pressure setting whichever is lowest, Initial Temperature of the water in the tank, and the Final Temperature of the water.

Worst case scenario tank on initial start up with a 40 degree incoming water temperature (good old winter time here in New England) being heated to 140 degrees F, on a tempering valve equipped water heater, you are looking at an expansion of....

30 gallon: 0.45 gallons
40 gallon: 0.60 gallons
50 gallon: 0.75 gallons
65 gallon: 0.98 gallons
80 gallon: 1.20 gallons
120 gallon: 1.80 gallons

Given that water cannot be compressed, if this scenario was played out on a closed system, without water usage or, leaks, the pressure caused by this expansion would first expand any parts within the system that can expand. This would continue until the set pressure of the T&P Valve or, secondary Relief Valve is reached and then the T&P Valve or, Relief Valve will discharge the water. The amount discharged will be a small amount as you can see in the worst case scenario with a 120 gallon tank it would be less than 2 gallons.... 

I had been arguing with a person on another forum which shall remain nameless, essentially that Thermal Expansion Tanks are the best means of pressure control in a closed system this is what NH Master was talking about in the initial post.

The person I was arguing with had the main point being that expansion tanks have an extremely high failure rate and it was better to use a secondary relief valve such as the Watts BRV Series Ball Valve Relief Valve as a means of controlling the pressure of thermal expansion. This valve has settings of 75, 80, 100 or 125psi.

The long rambling argument across many threads and quite some time also had options brought in by this person which included the Governor 80 Ballcock and Relief Valves installed on hosebibbs and boiler drains which I dismissed as not meeting code because they could be isolated from the water heater by means of a valve and in the case of the ballcock replaced with a Fluidmaster 400A by someone that did not know what they had installed and its additional function. This function of relieving the pressure through the ballcock could easily be seen as a failure of the ballcock. He was also arguing that these devices could prevent a water heater explosion due to uncontrolled heating which they cannot be guaranteed to do as they are not BTU rated reliefs.

My main points condemning the use of the relief valve only had several points.


The failure rate of properly installed Thermal Expansion Tanks was not anywhere close to what he was projecting.

The cost of installation difference between the Expansion Tank and the BRV Series Relief Valve was negligible and the relief valve is also subject to failure.

Failure of a relief valve, or activation due to a pressure increase could result in large volumes of water going unnoticed by the homeowner directly to the drain. At least until they get the "Shocker" quarterly water and sewer bill. :laughing:

Another point I brought in was the pressure cycling of the water heater tank as being detrimental to its service life. Pressure vessels do have some expansion that they go through as the pressure is increased and they also have some spring back as the pressure decreases. There are only so many cycles built into the design before metal fatigue causes failure of the vessel.

A prime example of a pressure cycling failure reducing the service life I use is the Aloha Airlines jet which despite its young age in years and low airframe hours had spent its entire service live flying short hops island to island in Hawaii. 










The pressure cycles on this aircraft numbered the second highest in the entire worlds 737 fleet with 89,090 cycles on a design good for 75,000 cycles. The same thing goes on in a water heater tank flexing under pressure increases and reductions. Each cycle fatigues the metal, cracks a little of the glass lining and eventually it's a leaker.

Use of the relief valve at the 75 and 80 psi settings are probably too low in many systems and would result in frequent activation and water waste. the use of the 100 & 125 psi settings would then result in minimum pressure cycles of 20 - 45 psi and lowered service life of the water heater. The pressure cycle for the jet flying at 30,000' was only 10.72 psi.

 Use of an expansion tank controls the pressure cycle to within a few psi and offers a much more regulated pressure through the cycles and extends the service life of the water heater.

That's my story and I'm sticking to it.
Use of an expansion tank on water heaters in a closed system is the best possible means of controlling the pressure of thermal expansion and ensuring the longest possible service life of the water heater in those conditions. :thumbup:


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## nhmaster3015 (Aug 5, 2008)

And....... that constant flexing of the water heater tank leads to cracking of the glass lining, which leads to rust, which leads to premature tank failure. Again, I can not believe the number of licensed, experienced plumbers that argue this issue.


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## Master Mark (Aug 14, 2009)

*Redwood....why////*



nhmaster3015 said:


> anybody ever actually see a relief valve loaded with scale to the point of failure.?


redwood, why did you have to start this crap on this site?? 

are you not having enough fun ???
the thermal expansion thread over there has really drifted into oblivion.... 

you better get back over there and stir up them enjineers...


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## Redwood (Sep 8, 2008)

Mark,
If you will note I'm not the original poster that started this thread....


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## Redwood (Sep 8, 2008)

nhmaster3015 said:


> And....... that constant flexing of the water heater tank leads to cracking of the glass lining, which leads to rust, which leads to premature tank failure. Again, I can not believe the number of licensed, experienced plumbers that argue this issue.


Me neither! My suspicion is that in some it may be ignorance and in some it may be a vested interest in selling higher numbers of water heaters.

Either way it's not a good thing in my book!:whistling2:


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## ToUtahNow (Jul 19, 2008)

It is highly unlikely you would see any damage at the water heater tank in a closed system. What is more likely would be a flooded house from a supply under a sink failing.

Mark


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## nhmaster3015 (Aug 5, 2008)

UL and other testing labs have done extensive testing of water heater expanison and one of the reasons why we need expansion tanks is because water does expand in the tank and flex the lining.


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## Redwood (Sep 8, 2008)

ToUtahNow said:


> It is highly unlikely you would see any damage at the water heater tank in a closed system. What is more likely would be a flooded house from a supply under a sink failing.
> 
> Mark


That is likely, as is an increased number of dripping faucets, & leaking ballcocks...

As long as the T&P is functioning the water heater would not blow out in most cases, it would just not last as long as it can...

If the T&P has failed all bets are off and hopefully something else does blow if it ever goes into uncontrolled heating...

I figure the 150 psi rating is probably 1/2 of the test pressure for a water heater. Would that be correct Mark? I'm not going to join ASTM to be able to read the testing standard but I assume you would have access...


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## Widdershins (Feb 5, 2011)

ToUtahNow said:


> It is highly unlikely you would see any damage at the water heater tank in a closed system. What is more likely would be a flooded house from a supply under a sink failing.
> 
> Mark


 Overpressure is going to take the path of least resistance.

That's a fact.

OTOH, it could be argued that defective or calcified/scaled heat trap nipples would/could confine the overpressure to the storage vessel.


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## Plumber Jim (Jun 19, 2008)

a couple months ago I changed out my brother inlaw's 2 50 gallon rheem heaters and they were only 7 years old. the plumber who plumbed the place put a check valve on the inlet of the meter and put an expansion tank upstream of the check valve. My brother inlaw didn't know that he had a thermal expansion problem because it never got to the point of popping a t&p. but both tanks developed leaks. I am sure that it was do to the constant expanding and contracting of the tanks. I replaced the tanks and installed an expansion tank and problem solved. I bet the new ones will last much longer.


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## ToUtahNow (Jul 19, 2008)

nhmaster3015 said:


> UL and other testing labs have done extensive testing of water heater expanison and one of the reasons why we need expansion tanks is because water does expand in the tank and flex the lining.


Tested in a UL Lab I agree 100%. However, in the real world there are things like washing machine hoses, ballcocks and different supply lines. Then if you add the different poly or PEX pipe as services and or potable water you add a bunch of expansion capacity. Absent all of the above you are in trouble.

Mark


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## Shadow Sabre (Oct 12, 2009)

Oh, so glad I stayed out of this one. Anyone want to buy a wood fired water heater. No worry's about thermal expansion in a big pot.

Sent from my iPhone using PlumbingZone


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## ToUtahNow (Jul 19, 2008)

Redwood said:


> That is likely, as is an increased number of dripping faucets, & leaking ballcocks...
> 
> As long as the T&P is functioning the water heater would not blow out in most cases, it would just not last as long as it can...
> 
> ...


Water heaters are an ANSI Standard (ANSI z21.10.1-2004) as opposed to an ASTM Standard. I believe 150 psi is the working pressure but they are certified to 300 psi. Most engineers would probably double that 300 psi in their design just to be safe.

You don't have to join ANSI to read the Standard but you do have to pay over $800 to buy it.

Mark


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## Prscptn Plmbng (Feb 15, 2011)

nhmaster3015 said:


> And....... that constant flexing of the water heater tank leads to cracking of the glass lining, which leads to rust, which leads to premature tank failure. Again, I can not believe the number of licensed, experienced plumbers that argue this issue.


On point!!! 

Some of these posts are just ridiculous, the biggest thing around here making plumbing systems a closed loop, is the extremely high service pressure from the municipality.... I check every paying customers water systems h2o psi static, run and for thermal.

How many plumbers here think it's safe or a good thing for a customers plumbing system to rise to 150+ (sometimes the t&p doesn't open to relieve) everytime the water heats??? 

The relief valve seeping water is just a tattle tale of the bigger problem... 

Expansion tanks out here are critical on most houses... Do your homework 

It's our job as professionals to take care of our customers plumbing systems


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## Redwood (Sep 8, 2008)

ToUtahNow said:


> Water heaters are an ANSI Standard (ANSI z21.10.1-2004) as opposed to an ASTM Standard. I believe 150 psi is the working pressure but they are certified to 300 psi. Most engineers would probably double that 300 psi in their design just to be safe.
> 
> You don't have to join ANSI to read the Standard but you do have to pay over $800 to buy it.
> 
> Mark


Ahh I new it was one of those....

And it was big $$$ to buy it....

So my plumber security clearance kicked in and said I didn't have, "A Need To Know." :laughing:

I figured the 300 certification for testing usually double the max pressure by what I've seen in other applications, and as I recall the MythBusters theirs popped at about 325 if I remember right...

Thanks Mark!:thumbup:


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## nhmaster3015 (Aug 5, 2008)

watts was blowing them up in the early 50's.

newer homes with lots of plastic pipe and supplies may better withstand the pressure increase however, around these parts the vast majority of homes are still piped in copper and galvy with hard supplies. the constant expansion and contraction withing the system is hard on everything, not just the water heater.


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## DUNBAR PLUMBING (Sep 11, 2008)

Replacing defective thermal expansion tanks is something I'm doing weekly, and that's because I'm looking for them whenever I arrive at the customer's home.


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## PLUMBER_BILL (Oct 23, 2009)

DUNBAR PLUMBING said:


> Replacing defective thermal expansion tanks is something I'm doing weekly, and that's because I'm looking for them whenever I arrive at the customer's home.


Question...Without draining the tank down and taking a pressure check, how can you tell if a tank is bad?

Answer ... Upon entering a property tell the owner as a saftey check for no charge you'd like to check their thermal expansion tank. Proceed to turn off the valve before the tank. Open a faucet if the water continues to run for about 10 secunds under pressure the bladder has air an probably the tank is good. If in opening a faucet the pressure is already off, you can assume the tank is bad.


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## Widdershins (Feb 5, 2011)

PLUMBER_BILL said:


> Question...Without draining the tank down and taking a pressure check, how can you tell if a tank is bad?
> 
> Answer ... Upon entering a property tell the owner as a saftey check for no charge you'd like to check their thermal expansion tank. Proceed to turn off the valve before the tank. Open a faucet if the water continues to run for about 10 secunds under pressure the bladder has air an probably the tank is good. If in opening a faucet the pressure is already off, you can assume the tank is bad.


 I usually just knock on them. If they're full you'll hear a thunk. If the bladder is still charged, you'll hear a ping.


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## Protech (Sep 22, 2008)

This is of course assuming you are on the top floor of the building and there is not an open loop solar heater installed.......




PLUMBER_BILL said:


> Question...Without draining the tank down and taking a pressure check, how can you tell if a tank is bad?
> 
> Answer ... Upon entering a property tell the owner as a saftey check for no charge you'd like to check their thermal expansion tank. Proceed to turn off the valve before the tank. Open a faucet if the water continues to run for about 10 secunds under pressure the bladder has air an probably the tank is good. If in opening a faucet the pressure is already off, you can assume the tank is bad.


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## DUNBAR PLUMBING (Sep 11, 2008)

PLUMBER_BILL said:


> Question...Without draining the tank down and taking a pressure check, how can you tell if a tank is bad?
> 
> Answer ... Upon entering a property tell the owner as a saftey check for no charge you'd like to check their thermal expansion tank. Proceed to turn off the valve before the tank. Open a faucet if the water continues to run for about 10 secunds under pressure the bladder has air an probably the tank is good. If in opening a faucet the pressure is already off, you can assume the tank is bad.


 

I try not to touch any valves but yes, that will identify. 

However, I catch failures even when there is air discharged still in the bladder side and water is already on the opposite side.

If you depress the schraeder valve, no air or air with any hint of water deems a failure, always.


As mentioned, you can usually shake the tank and it'll resemble a lead balloon on the water supply, the same as twicking it with your finger and you'll hear when the tank is full or empty.


Education is crucial on those tanks because people don't even understand what they are. That's why you always check them when in the home. Tell them they can do it themselves if they don't want to pay you... tell them what to expect, and explaining will most likely convince the replacement on your part.


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## Proud Plumber (Sep 15, 2008)

nhmaster3015 said:


> anybody ever actually see a relief valve loaded with scale to the point of failure.?


Yes... In fact I had two or three last year. NH I will try to get a photo that shows how nasty they get. All 5ish years old.


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## nhmaster3015 (Aug 5, 2008)

But they must have been weeping for awhile which causes them to crud up on the discharg but I have never seen one fail on the inlet side from hard water


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## Proud Plumber (Sep 15, 2008)

nhmaster3015 said:


> But they must have been weeping for awhile which causes them to crud up on the discharg but I have never seen one fail on the inlet side from hard water


They shouldn't be weeping at all. Until this past year I can't think of a time where I was called out specifically to replace a relief valve. Unless it was commercial preventive maintenance. The ones I pulled out were so packed with white snow on the inlet side. I don't know how they would have ever worked properly if they had to.


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## Redwood (Sep 8, 2008)

I wonder how many T&P Valves fail because of water constantly weeping through them from thermal expansion.... :whistling2:

Scale on the outlet side of the valve did not get there from the valve staying closed.... :yes:


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## DUNBAR PLUMBING (Sep 11, 2008)

The water heater I replaced yesterday? 


Someone had broke the entire front of the T&P off, bent the pin over, like it had no chance of opening up.


Sad state of affairs amigos. It only gets worse as the work gets less and less respected instead of inspected.


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## SewerRatz (Apr 25, 2009)

Had a customer e-mail me one day telling me she heard a loud bang type noise and when she went down stairs she saw her water heater had bulged. When I got there the water temperature was set at 125º no expansion tank, and interesting vent pipe for the power Vent.

She did have a duel check valve at the meter. So all I can figure is thermal expansion and a faulty T&P valve. We installed a new heater proper venting and a thermal expansion tank. Unit still going strong 5 years later. (Went there to hook up a gas line to a range.)


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## Protech (Sep 22, 2008)

Just think if the first guy had installed a relief valve with those expansion tanks, the system never would have felt any high pressure from thermal expansion when the tank when bad.

This is why I say a thermal expansion valve is MORE important than a thermal expansion tank. A tank and a valve is best, but if I have to choose between 1 or the other, the valve wins.



DUNBAR PLUMBING said:


> Replacing defective thermal expansion tanks is something I'm doing weekly, and that's because I'm looking for them whenever I arrive at the customer's home.


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## Prscptn Plmbng (Feb 15, 2011)

Protech said:


> Just think if the first guy had installed a relief valve with those expansion tanks, the system never would have felt any high pressure from thermal expansion when the tank when bad.
> 
> This is why I say a thermal expansion valve is MORE important than a thermal expansion tank. A tank and a valve is best, but if I have to choose between 1 or the other, the valve wins.


So you have the valve set to open at 80 psi to prevent excessive psi? 

With having the tank it doesn't even rise above 65psi...


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## Proud Plumber (Sep 15, 2008)

We have either checks on the meter or back flows. Expansion tanks are used and abused here. As for T and P relief valves. I agree with red on the weeping from thermal expansion. Here our city water is R.O. and the crappy yellow brass is like a second sacrificial point on the heater. LOL... popping them loose is almost like the gate valve gamble.


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