Hot Water Heater Pressure Relief Valve

[Koppster]

Friends:

I opened my hot water heater panel this morning and found some water. I believe the source is the pressure relief valve but would like some experienced opinions.

In the pictures you can see moisture on the plate directly under the valve and a very small puddle on the bottom right edge (gloss black area). The valve shows signs of water seepage residue.

From what I have read maybe I need to establish an air gap?

Thoughts?

Thanks
Rick

[ARoamer]

When COLD and with water pressure give that valve lever a workout, you may get wet! Maybe a bit of dirt or scale on it's seal. Same as home water heaters, that valve should be exercised occasionally. Never heard of an "air gap", you do not want air in your water heater, and air won't stay when you draw water anyhow. Dripping not a huge issue unless you full time. Should be a easy swap if it won't stop or gets worse, just replace with same rating valve.

[Grumpy]

Originally Posted by ARoamer

Never heard of an "air gap", you do not want air in your water heater, and air won't stay when you draw water anyhow.

The Atwood water heater tank is designed with an internal air gap at the tank to reduce the possibility of weeping and dripping. In time, the expanding water will absorb this air.

[ARoamer]

Thanks for the education Grumpy!

Seems odd to me to design in a temporary fix for a issue that shouldn't happen in a properly designed unit.

[norty1]

All water heaters have the same arrangement.

[SouthCo]

I wouldn’t worry about an occasional few drips unless it was a steady drip that never stopped.

[Grumpy]

Originally Posted by ARoamer

Thanks for the education Grumpy!

Seems odd to me to design in a temporary fix for a issue that shouldn't happen in a properly designed unit.

That is the proper design, it is to allow for the expansion during the initial heating. As it says the air gap.disappears over time once hot and being used. If the tank were completly full the relief valve would pop immediatelty when the water got hot and expands. The air compresses during that initial period so the valve doesn't pop open.

[CAG]

There is also a word or two on that subject in the water heater manual as I recall. Common problem when you load at low altitudes and camp at high. Simply give the lever a slight flip and generally the problem goes away.

[deepsea5]

Originally Posted by Grumpy

That is the proper design, it is to allow for the expansion during the initial heating. As it says the air gap.disappears over time once hot and being used. If the tank were completly full the relief valve would pop immediatelty when the water got hot and expands. The air compresses during that initial period so the valve doesn't pop open.

X2
Unless your RV has an expansion tank (AKA pressure tank), you will eventually face the above problem.

[JimD]

I replaced my tankless water heater with a Suburban tank model. Mine always leaks a little from the pressure relief valve when it first heats. Apparently, according to Suburban, this may be normal.

[LeMoeCND]

I installed a Waterline 3/4 inch x 54 inch relief drain valve tube. $7.52 CND. I just cut it very short to direct the weeping.

[16WhiteColly]

I drain my WH empty after every trip, and bleed it by opening the Pressure Relief Valve when filling, so I carry an extra with me, because I know it will go bad at some point, and want to be ready.

[ARoamer]

Originally Posted by Grumpy

That is the proper design, it is to allow for the expansion during the initial heating. As it says the air gap.disappears over time once hot and being used. If the tank were completly full the relief valve would pop immediatelty when the water got hot and expands. The air compresses during that initial period so the valve doesn't pop open.

That makes sense.

I must be lucky, I have never had that issue with a RV water heater's T&P valve, or I never noticed it. (Most likely!)

I'm never too old to be schooled.

[TWP723]

It can drip until the cows come home, I don't care. I only worry if it gets worse than a "drip".