Home>Discussions>PLUMBING>New Expansion Tank/T&P Valve Still Leaking
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mpriley05
Re: New Expansion Tank/T&P Valve Still Leaking

I don't think there is a check valve on the WH. Right now, the cold water supply is on to the WH, the breaker is on, and the house water pressure is at 110 psi and climbing slowly (it started at 40 psi this morning when the water supply to the WH was closed). The T&P valve has yet to leak today.

There is a pressure reducer on the line from the city supply. I don't think it is allowing backflow, or the pressure wouldn't build up in the house, right?

As far as the history, that's what the landlord said - they have leakage problems with the water heaters for a while. I don't know if he was talking about brand/style, etc.

There are no heat traps installed on the WH (at least externally that I can see).

Thanks

mpriley05
Re: New Expansion Tank/T&P Valve Still Leaking

OK - House pressure has hit 140 psi and the T&P valve started leaking like normal (a steady stream, not just dripping)

Blue RidgeParkway
Re: New Expansion Tank/T&P Valve Still Leaking
mpriley05 wrote:

OK - House pressure has hit 140 psi and the T&P valve started leaking like normal (a steady stream, not just dripping)

if that isnt a typo and house pressure hit one hundred forty psi then the water heater is prolly above 140 and your pressure reducing valve opened and is doing as it should.

the pressure getting that high is not safe for the plumbing or the electric water heater. something is wrong. notice you said something about the expansion tank was full of water.

heat traps can be in the ingoing and outgoing nipples.

not sure where you are and what controls you have but around here supplying safe and ready supply of hot water is required of the landlord when you rent out. this situation you describe wouldnt be acceptable or safe. if your landlord wont send out his own plumber immediately you might want to check with your housing authority or licensing of rental properties or a code inspector depending on how residential rental properties are regulated in your area.

i dont use electric for water heating but have had it in the past. if i remember correctly most have more than one heating coil in them so mabe one is faulty or needs to be balanced mabe it is going to hot or your inlet valve isnt opened all the way from you having to open and close it so much that the heater isnt all the way full before it starts heating on the top coil again? i really dont know. i do know a plumber should be able to figure out the problem and get it corrected darn quick and you shouldnt be reaching in a safe system 140 psi for sure.

JLMCDANIEL
Re: New Expansion Tank/T&P Valve Still Leaking
mpriley05 wrote:

OK - House pressure has hit 140 psi and the T&P valve started leaking like normal (a steady stream, not just dripping)

Are you sure your pressure reducing valve is working? If you get 140 psi to the WH it wouldn't take much more than a candle to raise the pressure above 150 psi.
Jack

mpriley05
Re: New Expansion Tank/T&P Valve Still Leaking

The incoming pressure into the house is 40 psi. It builds to 140 when the WH is on and the cold water supply to the WH is on. The pressure reducer should be OK.

This isn't something I would go to an inspector for. We don't have a lease. it's a very informal deal. Our landlord lives on the same property, and his son is the one that purchased the expansion tank and helped me put it in. They're trying to fix the problem, too. We just don;t know what it could be, so we're trying to get some advice.

Thanks

goldhiller
Re: New Expansion Tank/T&P Valve Still Leaking

"That's my story and I'm stickin' to it"....so to speak. ;)

Me thinks these WHs have a check valve/heat trap built into the nipple and that is what's causing the repeated problems the landlord is having with them. You should be able to look into new one and see the check valve down inside the cold water inlet side. IOW, if in doubt...go have a look at one....or disconnect the cold supply from this one and take a peek.

Whether these houses have a PRV or don't have one at all...an integral check valve will prevent the expanding water from being able to relieve itself back toward the city supply side. If the expansion tank is currently installed on the cold water/inlet side of the tank, it can't function because the expanding water can't back up toward it either.

*If* I'm right...then there would be two options to resolving the problem; 1- remove or disable the check valve/heat trap ...or... 2- install the expansion tank on the hot water side of the WH.

As far as the history, that's what the landlord said - they have leakage problems with the water heaters for a while. I don't know if he was talking about brand/style, etc.

Not sure what "for a while" means...but...there's a chance that if they've all initially acted this way and then quit at some point...eventually the check valve is weakened or distorted enough by these repeated high pressures that it begins to leak a bit...allowing enough water to escape back toward the city supply so that the T&P no longer drips.

The incoming pressure into the house is 40 psi. It builds to 140 when the WH is on and the cold water supply to the WH is on.

Where is your pressure gauge mounted when making these checks? Incoming cold side or on a hot line?

If on a hot line....

I'm thinking that if you cannot make the T&P stop dripping (relieve the pressure) by opening a cold water faucet in the house...that would be a pretty sure sign that the pressure is being held inside the water heater and the hot water pipes. It would also be a sure sign that the pressure is not able to access the cold supply...because of the prescence of a check valve in the WH. Not?

If on a cold line.... more thinking and analysis will be required.

mpriley05
Re: New Expansion Tank/T&P Valve Still Leaking

I put the pressure gauge on an outdoor spigot (cold only).

The pressure is being built up throughout the whole system, not just in the WH and the hot water lines. Opening any faucet, hot or cold, relieves the pressure.

The expansion tank is receiving water. It fills up as the pressure in the lines increases, and lets it back out when a faucet is opened.

goldhiller
Re: New Expansion Tank/T&P Valve Still Leaking

Dang and double-dang.

Time for more thought. Somewhere there is an answer. Finding it may be difficult this time.

Blake
Re: New Expansion Tank/T&P Valve Still Leaking

Have you checked to see if the thermostat is functioning properly and if the water is being heated beyond the thermostat setting?

canuk
Re: New Expansion Tank/T&P Valve Still Leaking

So to review.....

40 gallon electric hot water tank

water pressure from PRV is set to 40 psi

2 gallon expansion tank installed at cold water supply side of water heater

air charge for expansion tank is matched to water pressure of 40 psi

T&P is rated at 150 psi and engages

..... sounds like thermostat(s) in water heater are not working and allowing the heating elements to run full on constantly. It's over heating and causing thermo expansion which is also overwhelming the capacity of the expansion tank ..... building pressure all the way to the PRV increasing the preesure inside the home.

Just a thought.

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