Water heater pressure release valve

Three trailers and fourteen years later and have NEVER had one drip!

Replace it.

150 PSI? Why do you use a 40 or 50 pound regulator on the cold input?

150 would blow out every hot water fitting in the trailer.

My relief valve drips a bit but mostly when cold, heater off. As it heats up the dripping stops. Am told the seals are bad and when hot expand enough to seal. Trailer is only 1 year old. The dripping soaked the temperature cutoff fuse causing it to fail. Am planning to replace either with identical Watts valve or possibly a Cash Acme valve which some say is better.

If dripping is normal then do some thread in a piece of pipe so the water exists to the bottom of the heater access panel rather than onto the cutoff fuse? Or move the fuse out of the way of the valve and just let it drip?

they make a special wrench to take it out with it make the job way easier

Cool Canuck wrote:

fpresto wrote:

Cool Canuck wrote:
It is normal for it to drip. Change it if you want, but I can assure you the new one will drip as well.

I don't know where you got this idea. Does your home water heater drip? It is exactly the same valve. A properly working valve can only leak if the pressure and/or temperature is too high. The OP's issue is either temperature or pressure or most likely deposits built up on the valve seat.

The first words in my post was to READ THE MANUAL. Every trailer came with one. That is where I got that idea.

I'll make it easy for you.

The Suburban Manual wrote:

Pressure Relief Valve
The temperature and pressure relief valve is designed to open if the temperature of the water within the heater reaches 210oF, or if the water pressure in the heater reaches 150 pounds. Recreational vehicle water systems are closed systems and during the water heating cycle the pressure build-up in the water system which will reach 150 pounds. When this pressure is reached, the pressure relief valve will open and water will drip from the valve. This dripping will continue until the pressure is reduced to below 150 pounds, and the valve closes. This condition is normal and does not indicate a defective relief valve.

Some may ask "what makes it closed?" There is a check valve in the water connection that prevents water from traveling back to the street. Rv's need this so you don't pump your fresh water overboard. Your house does not have such a check valve and the water pressure can back up into the mains.

And the following is also from a Suburban Water Heater Manual (Same type of statement in Atwood WH Manuals)

One way to reduce the frequency of this occurrence is to maintain an air pocket at the top of the water heater tank.
This air pocket will form in the tank by design.
However, it will be reduced over time by he every use of your water heater.
To replenish this air pocket:
1. Turn off water heater
2. Turn off cold water supply line
3. Open a faucet in the RV
4. Pull out on the handle of the Pressure Relief (P&T) Valve and allow water to flow from the valve until it stops
5. Release handle on P&T Valve-it should snap closed
6. Close faucet and turn on cold water supply; as the tank fills, the air pocket will develop


Repeat this procedure as often as needed to reduce the frequency of the weeping of the P&T Valve

Air Pocket.....as designed....controls pressure increase due to expansion of water as it heats. Simple thermal dynamics.

RoyB wrote:
I would flip it off and on a couple of times... Mine will drip from time to time and that is what I can do to stop the the drip...

Roy Ken

Same here.

fpresto wrote:

Cool Canuck wrote:
It is normal for it to drip. Change it if you want, but I can assure you the new one will drip as well.

I don't know where you got this idea. Does your home water heater drip? It is exactly the same valve. A properly working valve can only leak if the pressure and/or temperature is too high. The OP's issue is either temperature or pressure or most likely deposits built up on the valve seat.

The first words in my post was to READ THE MANUAL. Every trailer came with one. That is where I got that idea.

I'll make it easy for you.

The Suburban Manual wrote:

Pressure Relief Valve
The temperature and pressure relief valve is designed to open if the temperature of the water within the heater reaches 210oF, or if the water pressure in the heater reaches 150 pounds. Recreational vehicle water systems are closed systems and during the water heating cycle the pressure build-up in the water system which will reach 150 pounds. When this pressure is reached, the pressure relief valve will open and water will drip from the valve. This dripping will continue until the pressure is reduced to below 150 pounds, and the valve closes. This condition is normal and does not indicate a defective relief valve.

Some may ask "what makes it closed?" There is a check valve in the water connection that prevents water from traveling back to the street. Rv's need this so you don't pump your fresh water overboard. Your house does not have such a check valve and the water pressure can back up into the mains.

When I changed ours on our Suburban water heater I found it made the job easier if I removed the heat vent shield, there's 4 screws holding it on. I when to Home Depot and bought a replacement, no drip after replacing it.

Denny

Cool Canuck wrote:
It is normal for it to drip. Change it if you want, but I can assure you the new one will drip as well.

I don't know where you got this idea. Does your home water heater drip? It is exactly the same valve. A properly working valve can only leak if the pressure and/or temperature is too high. The OP's issue is either temperature or pressure or most likely deposits built up on the valve seat.

rhagfo wrote:
Pressure relief valve should not drip, the air space has nothing to do with it.

This is correct.
Even if the air space is full of water the valve should not drip unless the water is too hot or the pressure too high. It should not leak just because it gets wet.
Further, the air space is full of water because the valve is leaking. Not the other way around.
I would snap it closed a few times to see if it will seal. After that just replace it if it acts up. They are a common failure item.

tn terry t wrote:
no one mentioned that these valves are temperature and pressure valves your heater could be getting a little too hot

They are set to lift at 210*F
Normal temp t-stats are preset for 130*F or 140*F
ECO (High Temp) are preset for 170*F or 180*F