Hot Water Relief Valve Drip Normal?

I have had that problem a couple of times when the coach has been in storage for long periods, and what I have done is I have gotten a screw driver and a small hammer, put the screw driver right on the end of the stem of the valve and give it a small hit with the hammer. That will reseat the valve to where it will not leak anymore for that year. It will probably do the same the following year when you bring it out of storage. Alkaline gets in the valve seat and causes the problem. But if it does not stop, then it is fairly easy to replace the valve. You can buy them at a Home Depot or Lowes.

phays wrote:
I've replaced the PRV on my previous motor home as re-establishing the air space didn't seem to help and the water released by the valve dripped on my connections and prevented the water heater from relighting. I assume the valve leaked both air and water since re-establishing the air space didn't solve my problem.

Not to hijack the thread but if the valve doesn't open until 150 psi, why doesn't the plumbing system in the RV rupture if the valve is leaking because of over pressure conditions? My understanding is that RV plumbing systems can only withstand 50 to 60 psi.

Winnebago tests their plumbing system to 85 psi. They told me setting my water pressure regulator at 65 psi was fine. It's worked okay at that pressure for ten years. We have spent entire summers in parks where the water pressure was way over 65 psi so the plumbing has been subjected to 65 psi for extended periods of time. The PEX tubing is rated to well over 100 psi I believe.

As a side note - the CO town where our summer home is has a supply pressure of 135 psi. When we bought the house last year we didn't realize the Watts house regulator wasn't working - who knows for how long. When I measured it the pressure was at 135 psi. Because i had th water heater replaced (the joys of home ownership) I had them replace the regulator at the same time. The tech recommended setting it at 65 psi which suited me just fine.

Of course you can always replace the valve with a new one and then see what happens...:h

Good luck & Safe Travels...:)

The T & P valve does not care if it's in air or water. As stated it only opens upon over temp or over pressure which an RV system will never see unless the unit way over heats.
I clean my water heater out every year when refilling I bled the tank with the T & P until water flows out just like your home unit.
Never had any sort of drip, leak nada nothing.

Because it OPENS at 150# or 210*F

Weeping is not 'opening'.......that is just leak by of valve face and seat caused by the increase in temp/press as water expands when heated in a closed system

PEX pipe is rated at 100 psi at 180*F, 130 psi at 120*F (temp/press related)

I've replaced the PRV on my previous motor home as re-establishing the air space didn't seem to help and the water released by the valve dripped on my connections and prevented the water heater from relighting. I assume the valve leaked both air and water since re-establishing the air space didn't solve my problem.

Not to hijack the thread but if the valve doesn't open until 150 psi, why doesn't the plumbing system in the RV rupture if the valve is leaking because of over pressure conditions? My understanding is that RV plumbing systems can only withstand 50 to 60 psi.

Clay L wrote:


Regarding why the air doesn't leak out - that is puzzling - but the fact is it doesn't and the pocket does prevent weeping.
I believe the water is just above the relief valve when the water is hot and perhaps the water can push on and compress the air easier than weeping from the valve?

That is because the PRV seals (valve against seat) when closed.
The air pocket allows for expansion of the water when heated (water is strange----it expands when heated and when frozen)
Without air pocket the heated water expands and pressure increases because water can not be compressed (air can). When temp/pressure increases it can cause the PRV to weep. The WH is a mini boiler and the PRV is a safety device to prevent explosion due to increased temp/pressure. Typically set at 210*F/150 psi---resets at 125 psi.

Mines 20 years old open and close twice a year when winterizing then when commissioning in the spring. If it drips a little give it a slight tap straight on to the lever.

Get a small SHURflo expansion tank for a permanent solution.

http://www.amazon.com/SHURflo-182-200-Pre-Pressurized-Accumulator-Tank/dp/B000N9VF6Q

I have reestablished the air pocket per Uncle Ts instructions (same as my manual says) several times over the years and the relief valve does not weep.
The manual says some weeping is normal but with the air pocket in place mine doesn't.

Regarding why the air doesn't leak out - that is puzzling - but the fact is it doesn't and the pocket does prevent weeping.
I believe the water is just above the relief valve when the water is hot and perhaps the water can push on and compress the air easier than weeping from the valve?