# Another recirc



## tim666 (Mar 11, 2014)

I am wondering if someone other than RJ and his cryptic replies could explain to me how a recirc line could work without check valves. I understand how the gravity recirc works but I am not grasping how it can be done without the check valves. We have done them (with pumps) on a 60 gallon electric water heater tieing back into the cold supply requiring 2 check valves and we have done them on an 80 gallon indirect which had a tapping in the middle of the tank for the return requiring only the one check valve 
Thank you


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## rjbphd (Feb 5, 2010)

tim666 said:


> I am wondering if someone other than RJ and his cryptic replies could explain to me how a recirc line could work without check valves. I understand how the gravity recirc works but I am not grasping how it can be done without the check valves. We have done them (with pumps) on a 60 gallon electric water heater tieing back into the cold supply requiring 2 check valves and we have done them on an 80 gallon indirect which had a tapping in the middle of the tank for the return requiring only the one check valve
> Thank you


Okay, 1st of all.. tying back to cold supply is incorrect,( where did you learn that from?) And how many check valve(s) have you seen on gravity hydronic heating system?


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## plumbdrum (Nov 30, 2013)

Who says It can't tie back into the cold supply?


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## rjbphd (Feb 5, 2010)

plumbdrum said:


> Who says It can't tie back into the cold supply?


Ever seen return line tied back to supply side of gravity system of boiler??


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## plumbdrum (Nov 30, 2013)

He said with pumps, so yes it could be done


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## rjbphd (Feb 5, 2010)

plumbdrum said:


> He said with pumps, so yes it could be done


Again, if its piped correctly, you won't need any pump... I've done a 5 baths single level home without pump and check valve.. no problems... til the new owner hired the handyhack remodeler


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## wyrickmech (Mar 16, 2013)

I think he is talking about a recirculating loop not a gravity boiler. Tying it into the cold with two checks is a proper install. It is also allowed to attach to the drain but you still need two checks this is the preferred way on residential at least around here. Commercial is normally in the cold supply of the heater.


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## plumbdrum (Nov 30, 2013)

Listen RJ, I respect your knowledge and all, but not everything you preach is gospel, the man asked a question, to which you said he was incorrect on connecting into the cold water supply. I responded to the comment and said it can be done ( although I do not prefer this method), point being there is 10 different ways to skin a cat to get the same outcome here. If you do not want to run pumps that fine, but the plumber asked a question , and also asked you specifically not to respond, and you still had to put your 2 cents in. Now I've done my fair share of ball busting here , but when somebody with a license has a legitimate question, I think it's our duty to give the seekers options, not opinions. We all put our pants on the same way and even you were once a little sniveling apprentice that was wet behind the ears like the rest of us were.


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## rjbphd (Feb 5, 2010)

plumbdrum said:


> Listen RJ, I respect your knowledge and all, but not everything you preach is gospel, the man asked a question, to which you said he was incorrect on connecting into the cold water supply. I responded to the comment and said it can be done ( although I do not prefer this method), point being there is 10 different ways to skin a cat to get the same outcome here. If you do not want to run pumps that fine, but the plumber asked a question , and also asked you specifically not to respond, and you still had to put your 2 cents in. Now I've done my fair share of ball busting here , but when somebody with a license has a legitimate question, I think it's our duty to give the seekers options, not opinions. We all put our pants on the same way and even you were once a little sniveling apprentice that was wet behind the ears like the rest of us were.


 Ya talking two different posts here... one asked me question and other didn't want to know..


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## tim666 (Mar 11, 2014)

rjbphd said:


> Okay, 1st of all.. tying back to cold supply is incorrect,( where did you learn that from?) And how many check valve(s) have you seen on gravity hydronic heating system?


Let's pretend it is a gravity hydronic system, let's also pretend the air vent is a hose bibb. If you were to open that hose bibb would you not be drawing from the supply and the return?


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## wyrickmech (Mar 16, 2013)

tim666 said:


> Let's pretend it is a gravity hydronic system, let's also pretend the air vent is a hose bibb. If you were to open that hose bibb would you not be drawing from the supply and the return?


would be irrelevant as long as it removed the air. Gravity Hydronic system is a different matter no need of check valves or pumps if installed right.


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## tim666 (Mar 11, 2014)

wyrickmech said:


> would be irrelevant as long as it removed the air. Gravity Hydronic system is a different matter no need of check valves or pumps if installed right.


That is the point I was trying to make to RJ


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## rjbphd (Feb 5, 2010)

tim666 said:


> Let's pretend it is a gravity hydronic system, let's also pretend the air vent is a hose bibb. If you were to open that hose bibb would you not be drawing from the supply and the return?


Nope, etheir... a u are drawing out/reducing pressure from the entire system assumming the hose bibb/vent is at top..


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## rjbphd (Feb 5, 2010)

wyrickmech said:


> would be irrelevant as long as it removed the air. Gravity Hydronic system is a different matter no need of check valves or pumps if installed right.


Same pricipcal as re circ line on hot water return line..


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## tim666 (Mar 11, 2014)

RJ you are not able to convince me that you will not draw from the return without check valve when you open a faucet


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## jmc12185 (Aug 27, 2013)

I always use a pump and check valves. I don't care if it may work with gravity.


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## rjbphd (Feb 5, 2010)

tim666 said:


> RJ you are not able to convince me that you will not draw from the return without check valve when you open a faucet


Water will flow with the least resistence .. which pipe will that be??.. the 3/4 or the 1/2 on the return?


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## wyrickmech (Mar 16, 2013)

rjbphd said:


> Water will flow with the least resistence .. which pipe will that be??.. the 3/4 or the 1/2 on the return?


that depends location of the faucet in the loop and developed length of the circuit. There is places that it could back flow and stop the thermal circulation then it would take time for it to start again.


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## SchmitzPlumbing (May 5, 2014)

the laing recirc manual shows it returning into the water heater through the cold inlet. thats how i install them. the old heating boss always told the plumbing boss (owner) that a pump was not needed. after a couple call backs on a bunch of installs or water heater change outs, i convinced him to make it a new policy to include a pump in the bid. he made more money and had no call backs.


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## rjbphd (Feb 5, 2010)

SchmitzPlumbing said:


> the laing recirc manual shows it returning into the water heater through the cold inlet. thats how i install them. the old heating boss always told the plumbing boss (owner) that a pump was not needed. after a couple call backs on a bunch of installs or water heater change outs, i convinced him to make it a new policy to include a pump in the bid. he made more money and had no call backs.


Love those crap Laing pump.. always taking them out and repiped it properly to bottom of heater.. no plm.. now in nar future, the unused electrical outlet will get used for new water heater standard


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## FRMA2Z (Mar 30, 2014)

Answering a question with a question is not the answer to the question in which he ask will it work ? Yes on a single run of hot line But when return lines are run correct and throughout from several locations in the system the answer will always be No..you can not T in returns and expect them to draw evenly even with balancing valves. The better question is why would you even take the chance for the cost of a check valve ? 
When I sell return systems on domestic hot water lines I always give the customer what they expect and that's a working system without any chance of back flow I won't risk my quality for the cost of a pump or a check ..Unless of course you didn't quote the job right 
We trouble shoot many of commercial projects where a cross connection exist over the cost of a check valve customers spend thousands looking for it when it's right in front of there eyes. Poorly run returns


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## SchmitzPlumbing (May 5, 2014)

rjbphd said:


> Love those crap Laing pump.. always taking them out and repiped it properly to bottom of heater.. no plm.. now in nar future, the unused electrical outlet will get used for new water heater standard


so you pipe them better than the manufacturer? i have yet to replace a laing. i guess you will put the pump business out of business. how do you balance your system with multiple recirc lines?


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## jmc12185 (Aug 27, 2013)

SchmitzPlumbing said:


> so you pipe them better than the manufacturer? i have yet to replace a laing. i guess you will put the pump business out of business. how do you balance your system with multiple recirc lines?


 you balance it by adjusting the gravity. Turn down the gravity on one to get more flow through the other.


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## rjbphd (Feb 5, 2010)

jmc12185 said:


> you balance it by adjusting the gravity. Turn down the gravity on one to get more flow through the other.


Perfect answer!..


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## jmc12185 (Aug 27, 2013)

Just takes a special gravity adjusting tool. But any descent supply house should stock them.


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## rjbphd (Feb 5, 2010)

jmc12185 said:


> Just takes a special gravity adjusting tool. But any descent supply house should stock them.


All I use is those balencing valve with screw driver slot .. been there for years on gravity system.


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## wyrickmech (Mar 16, 2013)

On unequal Leigh runs it's better to use a small pump with a product called circuit solver. Getting ready to install 13 in a local hospital with a variable frequency drive pump. It's a cool set up.


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## SchmitzPlumbing (May 5, 2014)

wayyyyy off topic for the boys, i run a wood boiler with a 20 plate exchanger on the entrance to the water heater. mixing valve on the outlet. 160 to 170 on the boiler. how do you do a recirc for this case and not go cold or overheat? serious question that i want your knowledge on.


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## wyrickmech (Mar 16, 2013)

SchmitzPlumbing said:


> wayyyyy off topic for the boys, i run a wood boiler with a 20 plate exchanger on the entrance to the water heater. mixing valve on the outlet. 160 to 170 on the boiler. how do you do a recirc for this case and not go cold or overheat? serious question that i want your knowledge on.


simplest way would be to pipe your recirculating line to the cold side of the tempering valve and to the plate exchanger. Water will circulate threw the plate into the tank then when it hits the tempering valve while idle the cooler water from the return will maintain a deference in the temp or while active the cold will cool the water. Just remember you only need to move the water a little not large gpm.


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## rjbphd (Feb 5, 2010)

wyrickmech said:


> simplest way would be to pipe your recirculating line to the cold side of the tempering valve and to the plate exchanger. Water will circulate threw the plate into the tank then when it hits the tempering valve while idle the cooler water from the return will maintain a deference in the temp or while active the cold will cool the water. Just remember you only need to move the water a little not large gpm.


Didn't see any check valve(s) here as needed


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## tim666 (Mar 11, 2014)

rjbphd said:


> Water will flow with the least resistence .. which pipe will that be??.. the 3/4 or the 1/2 on the return?


Friction loss through the fittings on the 3/4" would practically make up for the 1/2" return with no tees


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## wyrickmech (Mar 16, 2013)

rjbphd said:


> Didn't see any check valve(s) here as needed


 yes I forgot check on pump and one on cold incoming water.


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## HonestPlumb (Jan 25, 2015)

wyrickmech came up with IMO the most logical and properly functioning set up (with the checks).


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