atwood 10 gallon water heater

RV water heaters have 'air pockets' for expansion..water expands when heated and does not compress. Air does.

RV water heater 'normal' t-stats open at 130/140*F (pre-set fixed temp)
RV water heater 'High/ECO' t-stats open at 170/180*F (pre-set fixed temp)
RV water heater 'Press/Temp Relief Valves' open at 210*F/150 psi
RV water heater PRVs temp probe are submerged in the water below the air pocket

Dripping from PRV's is when heating water is typically due to loss of 'air pocket'.
Turn off water supply
Open hot side on faucet to relieve pressure
Open PRV via lever until water stops running out...then let it snap closed
Turn on water supply
Close faucet.

Our pressure relief valve leaked like that. We re-established the air pocket and it stopped leaking. Give it a try.

Not sure I agree about an air pocket in the top of the hot water heater. I realize the benefits, but would be concerned about impacting the functionality of the T&P valve. The valve not only releases on excess pressure, but excess heat too. The valve probe should be submerged for best effectiveness. 140 degrees is a pretty typical hot water temp. Most household T&P valves are 170 degrees and 150 psi. Never checked the tag on the camper......

Sorry double post

J Walker wrote:

amxpress wrote:
According to Atwood, it is suppose to open at 140 Degrees.
Maybe the question should be, why is it getting so hot?

The Atwood water heaters work at a high thermostat setting, non adjustable. I haven't measured my water temp but it must be close to 140 degrees. The pressure relief valve works on pressure generated by the expanding water.

You nailed it, it's usually not the temperature that triggers the relief valve, it's the pressure because there is not air gap for water to expand when being heated. RV's plumbing is a closed system with a check valve at the water inlet. It would amaze you if you put a pressure gague on a faucet in or outside the rv how much pressure will build in the system...

amxpress wrote:
According to Atwood, it is suppose to open at 140 Degrees.
Maybe the question should be, why is it getting so hot?

The Atwood water heaters work at a high thermostat setting, non adjustable. I haven't measured my water temp but it must be close to 140 degrees. The pressure relief valve works on pressure generated by the expanding water.

According to Atwood, it is suppose to open at 140 Degrees.
Maybe the question should be, why is it getting so hot?

One thing to try before replacing the pressure relief valve is to make sure there is an air pocket at the top of the heater. Turn off the gas and electric heater, disconnect the city water, and turn off the pump. Open a low point hot water drain. Open a faucet such as the sink faucet. Drain some hot water out. Re-connect the city water or turn on the pump. See if that does the trick. Next step if no solution is to replace the pressure relief valve.

Could be a faulty relief valve...easy to replace.
Try this first:
Re-establish an air pocket in the water heater tank.

Water Heater Air Pocket
Shut off the water supply, open the relief valve until water stop coming out, close it, turn the water supply back on.
This will reestablish the air pocket in the water heater, giving the water some place to expand to when it is heated.