suburban water heater relief valve - dripping

Had the same problem with our water heater during a spring break trip to the Texas hill country. Normally I flush the water heater before beginning our camping season. However, since we left Colorado in freezing conditions, I had no water in the system when we left and during our first overnight in Texas, after filling the water system, the water heater began to leak at the temp/press relief valve. Went to Ace H/W and picked up a new one. Installed it and the problem went away. Upon inspecting the old one, there was considerable debris stuck in the valve, either due to my not flushing the tank beforehand, or just age. At that point, it didn't really matter as everything worked fine during the trip and all continues to be ok. I flushed the tank this spring anyway just to be sure all of the debris was gone. Replacing the relief valve is pretty easy.

Best regards,

Lowell

After the water heater gets up to temperature, open a hot faucet and run a little water. Did that stop the seeping?

Water expands when heated.

The Full name of that valve is Temperature/Pressure Relief valve.

Let's ignore Temperature as well. that's not the problm. Temp relief is a woods metal plug, it melts and NIAGARA FALLS level leak then happens and you have to replace the valve.. So that's not the problem.

Drip, Drip, is the pressure relief, this is a spring against a valve seat.

Now, there are three common causes of that drip This is NOT in order, in fact if anything it is in reverse order

1: Bad valve, weak spring (not common)

2: No inlet pressure rebulator (See below) Too much city water prssure, as the water heats the pressure increases, and DRIP DRIP DRIP two solutions

3: No "Air space" So as the wate heats the pressure rises much faster than it should, again two solutions

The easy solution to #3: Drain, flush and re-fill the heater.. To do this shut it off, let it cool (Safety issue) or run water till it's cool.. Then operate bypass valves to stop water entering. Remove lower drain plug and (on some models) the attachend anode, If anode attached inspect and get a new one if needed, if not attached, Well then no need to get a new one (The plug will be Nylon and likely a witch to remove in this case).

I replace the plug with a pipe, then open the TPR and let it drain. Close TPR, replace origi8nal plug (or new anode plug) and turn the water back on. Wait a minute or two (for flow to stop) and turn heater back on.


The hard method and common to 2 and 3: Some water heaters have a check alve on the INLET,, Remove this valve, it is not needed.

Finally the solution to #1.. Over pressure on the city supply.......

There are several regulators.. I( wi9ll classify all but one of them.

1: Standard.. This is a plastic or brass cylinder, about 3/4" in diamater, may or may not have a gauge on it.. Also HI-FLOW, models, same as above but usually have a bright plastic grip.. Good for dish washing, NOT enough capacity to feed the shower.. I rate them about a 1 and 2 on the old scale of 10.

Valterra adulstable: I do not have one and have not tested it but others give it a good rating

Sur-Flo.. (A Watts corporation) This is the type that is pre-installed as part of the city wate rinlet on many Motor Homes. Mine is an "inline" model, the exact same regulator but with a male hose fitting screwed on the outlet. and no "Benzel" attached.. But it is the exact same regulator I give it a 9 when new

Watts, and Zurin Plumbing supply house (Also Home Depot/Lowes) types.. These have a brass lower body and a bell shaped (Also brass0 Upper body with a bolt sticking out the top of the bell (where the handle would go on a hand bell).

Mine are 3/4 inch.. But I suspect a half inch would work as well, They do not fit Garden Hoses (thouh I have seen them sold with adapters both "in the package" and pre-installed like my Sur-Flo) but on the old 10 scale they score a nice solid 11 when new.

All of them: You know the old joke about Bo Derrek Gettin older (What goes 10-9-8-7......) Well they do. As they get older the internal parts stiffen and they begin to restrict water flow.. Watts, Zurin and I suspect the Sur Flo (though I have yet to research) can be renewed with new internal parts.

I plan on rebuilding my watts soon as I remember to get a kit,, Same for the Sur-Flo,,, Zurin is too new to need it.


How good are these "Whole House" type... Well I put a pressure gauge on the outlet using a "Y", and set it to 50 PSI (RV says macx 45 but 50 is safe for mine so I use 50). Turned on the shower and watched the needle... it did not move, it acted like it was stuck on 50 (moved when water was turned off and disconnected though).. I mean it did not move (new Zurin) A decade old unit the pressure would drop down to less than 20 PSI. Same with the cylinder jobs.

kmb1966 wrote:
Is this usually just a bad valve needing to be replaced?

I just had mine replaced because of that.......and the new one still drips a bit but ONLY until you open a hot water faucet after the tank heats up.

It looks to me like the pump system with it's check valves and all has almost NO room for expansion. As the water heats up, the pressure goes up......a LOT apparently.

If you can release the pressure at a hot faucet and the drip stops, I wouldn't worry about it. But make sure it isn't dripping on any electrical connectors or other critical parts.

You may want to check the thermostat. My brand new mh was doing that and turned out the thermostat was not seated properly. Water got to hot and the valve was doing its job.

SDcampowneroperator wrote:
Whats the camp water pressure? Your temp. setting on your regulator?
Relief valves are designed to vent at excessive pressure or temperature, so perhaps one or the other too high.
Start with pressure. Temp/ pressure relief valves have a curve related to each.

Water heater TPRV (Temp-Press Relief Valve) are pre set to OPEN at 210*F/150 PSI

RV Water heaters have a tendency to 'weep' due to small closed hot water system of the RV.....hence the need for the 'Air Pocket' at top of RV water heater tanks (by design)

Normal filling of water heater usually allows for air pocket....opening TPRV with water supply turned on can displace air pocket and air pocket can get absorbed into water.

Air pocket allows for expansion of water as iot is heated w/o a large increase in pressure.
Water swells when heated...water can NOT be compressed. W/O air pocket pressure will increase enough to cause TPRV to weep






And YES....TPRV can just be a leaker due to build up on valve/seat. Replace if needed.

With a 2001 RV and if TPRV has been a weeper......time to replace

Best to remove old TPRV first......some are 1/2" NPT and some are 3/4" NPT

Whats the camp water pressure? Your temp. setting on your regulator?
Relief valves are designed to vent at excessive pressure or temperature, so perhaps one or the other too high.
Start with pressure. Temp/ pressure relief valves have a curve related to each.

It could fix it. . .but if a small particle is caught in the valve, then it might not.
The PRV is standard and can be replaced with a new one from places like Home Depot, Ace, lowes, etc.

Do what rv2go above posted.
Bet it fixes it.

It may be corrected by simple restoring the air pocket.

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. If the weeping persists after following this procedure, you may elect to install an expansion or accumulator tank in the cold water line between the tank and check valve to relieve the pressure caused by thermal expansion.