Hot water heater problems

[phoenix]

Hello all,

I've got an AOSmith 40 gallon gas hot water heater, approx 2 1/2 years old in a new construction house.

Lately the pressure relief valve on the side has been discharging close to 2 gallons a day, not a constant drip so i assume it's only discharging when the pressure gets too high.

i've got the temperature in the tank set lower than the factory setting and usually don't have more than one hot water using fixture going at the same time (ie dishwasher, shower, washing machine)

Do i have a bad pressure relief valve?
Do i have a bad expansion tank?
is this functioning as intended and should i just install a drain?

any help would be greatly appreciated

thanks in advance
-Jason

 

[countryboy26047]

I've never known of a PRV releasing any amount of water unless it's either A) As you said, a bad valve, or B) possibly a bad t-stat controller causing the water to get hotter than the actual set-point?

 

[phishfood]

My first guess is that the expansion tank you mentioned has gone bad. With the house main shut off and water pressure drained, use a tire gauge to check the air pressure in it.

T&P valves do go bad, but it is not all that common.

It is also possible that a thermostat is sticking on sometimes, but the red ECO switch should be cutting out if that is the case.

 

[Caduceus]

I agree with phish and it should be added that when you check the pressure from the schrader valve on the expansion tank if you get water from the valve, not air, then the bladder is definitely ruined. If this is the case, be alert when turning the water back on. Little pieces of the disintegrated bladder may clog the schrader valve and water will squirt out of it. Don't panic. You can match up the same size of expansion tank (there are usually two common sizes) at a home improvement or hardware store.
Also check the house pressure with a gauge. The expansion tank may need to have air pressure added to equal the house pressure. They come pre-charged with air @ 20 psi or 40 psi.

 

[phoenix]

Thanks for the replies guys,

I secured the main water to the house and started draining the pressure

using a tire pressure gauge on the valve at the bottom i was unable to activate it while under pressure

water pressure partly drained i got a reading of around 24psi

when water pressure was fully drained the tire gauge read 0psi

the tank states it has a pre-charged pressure of 20, a max charged pressure of 80, and a working charge pressure (with water) of 150

should i be getting a zero reading with the home water pressure drained? also no water came out while performing the check


thanks!

 

[phishfood]

No, it should still have some pressure in it. You can use a tire pump to bring it back up to 40 lbs, but I am thinking that it will loose it's charge again sometime soon. Try soapy water sprayed on the air pressure valve where you checked the pressure and see if you get air bubbles after you re pressurize it.

 

[phoenix]

No, it should still have some pressure in it. You can use a tire pump to bring it back up to 40 lbs, but I am thinking that it will loose it's charge again sometime soon. Try soapy water sprayed on the air pressure valve where you checked the pressure and see if you get air bubbles after you re pressurize it.

thanks Phish,

I was able to re-pressurize it to 40, will check to see in a few days how the pressure is holding and obviously if i don't see water coming out of the pressure relief on the hot water heater i guess that was the problem

thanks for all the help, i appreciate it!
-Jason

 

[phoenix]

well its been almost a week now and it's stayed bone dry so i guess that was indeed the issue.

thanks again for all the help!