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Old 06-01-2016, 10:19 PM   #1
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hot water expansion questions


i have been in this house for many years...when i moved in there was no water expansion tank or relief valve (except the usual one on the side of the water heater).

at time of water heater replacement, a WATTS POPPET type relief valve (set at about 95psi) was added.. the normal pressure is set at 65psi.

the poppet started to drip (at all times) a couple years later, had it replaced, now about 2 years later that one drips constantly too.

so questions, before i take the next step-

1. do i need an expansion device?
***NOTE i looked at my neighbor's and a couple other friends' houses, they don't have any expansion relief device either.

2. if yes, is better to have an expansion tank? i am concerned about water standing in contact with rubber diaphragm...(may be not an issue).

3. is there a better relief valve than the usual WATTS brand commonly available onlne?

thanks
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Old 06-02-2016, 08:20 AM   #2
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Re: hot water expansion questions


Have you checked the water pressure to see if the valve is doing it's job?
Simple to check, just screw one of these on an outside faucet.
http://www.homedepot.com/s/water%252...20gauge?NCNI-5
Where did they install this valve?
Flipped it open and closed a few times to see if it will reseat?
Water sitting in contact with the diphram is a none issue, there's millions of bladder tanks in use everywhere.
http://www.watts.com/pages/learnabou...lExpansion.asp
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Old 06-02-2016, 11:13 AM   #3
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Re: hot water expansion questions


Each new tankful of water will expand a little when heated. Water does not compress noticeably to make up for this. So something in the plumbing system must give.

In some homes water will back up into the water main to compensate for the expansion. Gradually, water companies have been equipping homes with devices that prevent this backup, sometimes in connection with other functionality such as pressure regulation. Then an expansion tank is needed or else the temp. & pressure relief valve on the water heater has to deal with the expansion.

Sometimes there is an air pocket in the plumbing that really should not be there but that compensates for the expansion of the water being heated.

Most cities' building or plumbing codes nowadays require an expansion tank for the water heater.
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Last edited by AllanJ; 06-02-2016 at 11:18 AM.
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Old 06-03-2016, 02:01 AM   #4
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Re: hot water expansion questions


Quote:
Originally Posted by joecaption View Post
Have you checked the water pressure to see if the valve is doing it's job?
Simple to check, just screw one of these on an outside faucet.
http://www.homedepot.com/s/water%252...20gauge?NCNI-5
Where did they install this valve?
Flipped it open and closed a few times to see if it will reseat?
Water sitting in contact with the diphram is a none issue, there's millions of bladder tanks in use everywhere.
http://www.watts.com/pages/learnabou...lExpansion.asp
1. a added a pressure gauge near the feed to heater on the cold side so i can see the pressure at any time.

2. yes, the POPPET was and is doing it job...when the water heater fires up, the pressure starts to rise form the steady 65 till the poppet starts to drip...

3. the issue is the POPPET is now wasting water as drips all the times

4. the popper does not have a flip lever like the usual relief valve...only and adjustment knob...
http://www.supplyhouse.com/Watts-037...alve-3569000-p

i adjusted it up and down but that does not stop the drip

i guess i can add a tank...and not worry about standing water and contact with rubber.
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Old 06-03-2016, 11:27 AM   #5
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Re: hot water expansion questions


I'm not sure how those poppet relief valves work. Someone here will know. Sounds like it's doing its job.

I agree, you could add an expansion tank, that should help with the thermo expansion.

I mostly see the regular flipper relief valve with an expansion tank on the incoming cold water line to water heater. You set the expansion tank to your incoming water pressure, in your case 65psi.

If your incoming water pressure was over 80psi (which yours is not) then you would need a water pressure reducer as well to keep the water pressure at a normal 50-60 psi. At 65psi., you are good, and don't need one.
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