Water Heater "pop-off" Valve

[jkbriggs]

Turned on water pump (after bus had been sitting unused for a month or so) and noticed water leaking from the overflow tube underneath that connects to what I think is the water heater pop-off valve (on side of WH). What does this mean? Replace just valve (I hope) and not the whole WH? WH is old and would be a tough replacement because of surrounding plumbing/filters, etc. Valve can bee accessed pretty easily.

[Will Garner]

Jody,

Pop Valves typically protect from an over pressure condition within the water heater. They are usually shut, everything working fine, or open with water or steam discharging at a greater rate than just a drip, unless your pumps are of or you have run dry in fresh water tank.

This is only a suggestion. Replace the Pop Valve, also referred to as a safety valve, and see if your problem goes away. Last spring I had one of my Pop Valves that would not release during a check. There was nothing I could use to get it to open. This is not a good thing when the valve is for protection against an explosive rupture of the water heater. It was no big deal to replace it - just could not get a replacement at the nearby Lowe's. I had to go to an RV dealer about 45 miles away. Get some teflon tape to seal the threads on the new valve just like you would use in replacing a bathroom shower head.

Good Luck!

[Will Garner]

Jody,

One other use for the "Pop Valve" is to flush the water heater of any built up sediment.

In case you were not aware, "Pop Valve" is an old boiler makers term for a device used on the business end of the old steam fired railroad locomotives. There were generall two of these devices just forward of the cab on the boiler.

[Jon Wehrenberg]

You can easily unscrew the valve (obviously depressurize the water system and drain down thwe HW tank a little) and take it to Lowe's to get a direct replacement. I replaced one on each of our coaches now.

I think they are about $14.00

[jkbriggs]

Thanks! I will remove it & go to Lowes.

[Petervs]

Mine seem to weep a little at times. I have replaced them, same result. Since the engine coolant heats the fresh water in the water heaters as well as the Webasto or electricity, the temperature can get really close to the set point on the relief valve. These valves open when either the pressure or temperature exceeds the design set point.

I think the valve opens at 195 degrees F, and the engine coolant is right near there hence the situation.

Since it is only hot water dripping on the ground I do not worry about it.

[dreamchasers]

Jody,

I just replaced both of mine. Unfortunately, Lowes here in Livingston,
Texas only stocked 3/4", but I needed 1/2". I ordered mine on the internet.

Easy to replace.

Hector

[Coloradobus]

Its not that simple. Most hardware stores we found don't stock the 1/2 inch popoff valves. We had to go to an RV dealer.:(

[Jon Wehrenberg]

Thats why they make pipe fittings that go from 1/2 to 3/4.

[jkbriggs]

I must be living right. Home Depot had 3/4" in stock and it only cost $7.49 (Jon, you were way off with that $14.00 estimate! - just kidding).

[Jon Wehrenberg]

I got cheated. Damn.

[JIM CHALOUPKA]

Jody, did you get the 3/4 to 1/2 adapter?

JIM

[jkbriggs]

Jim, I didn't need an adapter. The value is 3/4" as was the one I purchased from HD (I got lucky on this one!).