Water Heater Wont Shut Off

Dano, it seems odd that the thermo and pressure valve are both failing at the same time. Are you sure the water is "over temp". Remember with only 10 gals by the time you moderate it with cold water you really don't have "much" hot water.

What you say is (nearly) impossible. Has anyone messed w/ it (maybe bypassed) lately ?

It is a 2002 hr 5er that the po's spent summers in, it has no road miles. They told me that the water heater was doing that lately and they controlled it the way I described. The 1st thing I could think of was replace the therm and eco, cheap enough, right? I've owned many rv's in my life, and this one is either gonna be a flipper, or gonna be parked somewhere, and the water is hotter than any rv Ive ever owned. The wiring is all correct, I've checked it against a diagram, I think I will run it and see if I can get a temp on the water running out of the faucet. At least that will tell me if the tpv has failed.

What is the temp of the water.....measure it at the PRV?
CAUTION: Normal t-stat is pre-set for 140*F and the ECO is pre-set at 180*F

PRV lifts at 210*F or 150 PSI

The t-stats MUST be held tight against the tank wall and that area needs to be CLEAN for good contact.

IF you can wiggle the t-stats they are not tight.

Usually the 'normal' t-stat will fail because it OPENS/CLOSES on each heating cycle. The ECO stays CLOSED unless normal t-stat fails to OPEN then ECO will OPEN on high temp (and throw the 'fault light')

SO has the RED fault light come ON?

IF PRV is leaking during heating cycle it could be due to 'loss of air pocket' at top of tank.
Air pocket is there to allow the expansion of the water as it heats without a big increase in pressure.
Without the air pocket....water expands when heated and pressure increases (can't compress water...can compress air)
The air pocket can get absorbed into the water over time....or just not get established.

To re-establish air pocket:
Turn water supply OFF
OPEN nearest faucet...hot side...to relieve pressure
OPEN PRV via lever.......CAUTION HOT......leave OPEN until water STOPS flowing then let PRV snap CLOSE
Turn water supply ON
CLOSE faucet.

Oh and when I replaced the therm and eco nothing changed.

OB, we're talking electric, not propane, red fault light for electric, where is that located?? Like I said I've owned many rvs and yes the t-stat is installed right. I will try to test the temp of the water at the prv without getting scalded, and the air pocket is there, its one of the first things I checked. And the prv isn't leaking, its spraying everywhere, and is that a home depot part??

dano73 wrote:
OB, we're talking electric, not propane, red fault light for electric, where is that located?? Like I said I've owned many rvs and yes the t-stat is installed right. I will try to test the temp of the water at the prv without getting scalded, and the air pocket is there, its one of the first things I checked. And the prv isn't leaking, its spraying everywhere, and is that a home depot part??

The same RED fault light that comes on when propane fails will also come on electric when ECO Opens.

The t-stats (normal & ECO either work or don't)


PRV....can get them at hardware....just need to be sure same thread size.
IF PRV is bad......water is scalding hot above 125*F. And will steam thru a leaking PRV.

See you do learn something everyday, I don't think the red fault lite has come on when the prv is blowing out. So basically if the water is blowing out below 140 theres a good chance the valve is shot.