Leaking pressure relieve valve

[FCStreamer]

My wife noticed that the pressure relieve valve of the water heater drips water when the water heater is turned on.



It's the blue circle on the top right.

The instructions say this is not a malfunction, and they give a procedure to restore an "air gap" in the tank.

Question. How often does this procedure need to be done? Should I be worried?

[OTRA15]

Originally Posted by FCStreamer

My wife noticed that the pressure relieve valve of the water heater drips water when the water heater is turned on.
. . .
The instructions say this is not a malfunction, and they give a procedure to restore an "air gap" in the tank.

Question. How often does this procedure need to be done? Should I be worried?

I don't think you should be worried, and I don't know how often this happens. Every time you turn on the water heater from a cold state, you should open a hot water faucet briefly a few times to let pressure out. The newer heaters get hotter than the old ones, and rely on a tempering valve to mix in cold water so the hot faucets do not release scalding hot water. This makes our 5-6 gallon water heaters "go further" than the old ones.

You might also be suffering from using your local city water which may have lots of mineral content, which translates into grit in the pressure relief valve. When the water tank has cool water in it, and with very little city water pressure in your system (just crack the hose bib connection open a little), you can operate the pressure relief valve handle to let some water escape. Do this a few times in a row and put the lever through its full range of motion (like 120 to 150 degrees plus or minus). You may even see some mineral grit come out.

If this keeps happening, you might want to replace the pressure relief valve. Most of them are pretty generic and your local hardware store or plumbing supply house should have one. Might as well get two while you're at it. Need to seat it in Teflon tape too.

Good luck.

Peter

[CruizinDux]

Just to build what Peter described. I'd remove it and go to a plumbing supply. Most residential are both temp and pressure relief. To be honest I've not noticed if ours is both but I would match the function and the T & P thresholds for opening of the OEM part in you AS.

Also key is the grit. Generally they are better replaced as opposed to trying to eliminate the grit, tho you should thoroughly flush your tank with a wand....note the outflow grit if any.

Many plumbers say don't touch the PTRV as they are temperamental and once opened have a propensity to open again often below threshold T or P. I open mine at winterization to make it drain faster and easier to winterize...but I'm also wiling to swap it our at the first sign of a leak. Cost is nominal.

Bob

[OTRA15]

PS and to tag along on Bob's comment about grit -- all fresh water added to the trailer, whether by hose to the tank, or by hose to the city water connection, should go through a standard particulate filter, as standard procedure. I rigged up a residential one in between two lengths of hose. This is crucial especially if you get water from a campground which has well water. No harm in adding an inline water pressure regulator also IMO, even though our city intake fittings now contain a pressure regulator. Belt and suspenders stuff, don't you know . . .

Your water heater's pressure relief valve could also have plain old grit in it, not just mineral deposits from that Florida water, as I believe Bob was thinking.

Peter

[HiJoeSilver]

It's pretty normal in this type of situation. The AS water system is closed and as delivered has no surge volume. When you turn on the water heater the water in it expands as it heats up but that expansion has no place to go so pressure increases, this causes the TPV to relieve the pressure by opening a tiny bit to let some water escape.

The instructions say this is not a malfunction, and they give a procedure to restore an "air gap" in the tank.
Question. How often does this procedure need to be done? Should I be worried?
It depends on a lot of factors but if you're traveling a lot, connect/disconnect a lot it will be more often.

I wouldn't be too worried about it.

Sure flow makes a small expansion tank that you could install in the water system which will provide some expansion volume, eliminating the need for the bubble in the hot water tank and stopping the TPV from opening. Plus it smoothes out the pump operation when you're using the potable water pump.

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

[dkottum]

It's a closed system, needs the water heater air bubble. Easy way when traveling is to hook up city water then open a hot water faucet first. This will send the column of air in the hose into the water heater where it will stay for the time being.

We decided to install a water pressure accumulator under the bath sink, just take off the cold water line from under the bath faucet, put it on the accumulator. Then add a new line from the accumulator to the cold water faucet, and fasten it to the wall. This will give a cushion of air that is separated from the water system and cannot be lost.

[CruizinDux]

Originally Posted by OTRA15

Your water heater's pressure relief valve could also have plain old grit in it, not just mineral deposits from that Florida water, as I believe Bob was thinking.

Peter

correct.

b

[TG Twinkie]

The area above the hot water outlet in the water heater is intended to be the expansion chamber.
To reestablish this air cushion. Turn the pump or city water off. Open the drain plug (or remove the sacrificial anode). Lift the lever on the pressure relief valve and drain a gallon or so. Then let the pressure relief snap shut. Replace the plug or anode.
Open the hot water valve at the sink and turn on the pump or city water. Let it run until all air is out of the lines. At this point the water heater level is correct.
It is not uncommon the pressure relief drips periodically.

[HiJoeSilver]

Originally Posted by TG Twinkie

The area above the hot water outlet in the water heater is intended to be the expansion chamber.
To reestablish this air cushion. Turn the pump or city water off. Open the drain plug (or remove the sacrificial anode). Lift the lever on the pressure relief valve and drain a gallon or so. Then let the pressure relief snap shut. Replace the plug or anode.
Open the hot water valve at the sink and turn on the pump or city water. Let it run until all air is out of the lines. At this point the water heater level is correct.
It is not uncommon the pressure relief drips periodically.

Correct, except don't remove the drain plug. If you do you'll just drain the whole tank. Open the TPV valve until water stops coming out, then let it close. This will drain water down to the level of the TPV, leaving air bubble above it.