We have an Atwood Gas/Electric model water heater in our 10-year old motorhome.Recently we have been having water dripping/spurting out of the blow-off valve opening when the water heater is in operation.Also, my wife said she didn't have very hot water for her shower the other day. That seemed to be an isolated incident as since then, the water heater has worked fine on gas or electric.....except for the water dripping/spurting out of the blow-off opening.What could be the cause of this issue?

They can act up - especially when they get some age on them. Sometimes it is as simple as a small piece of dirt or scale is caught in the valve not allowing it to seal properly. Turn the heater off and let it cool down so you don't get burnt, then push the lever on the valve a few times to try and blow it out. If that doesn't work, the easiest thing to do is replace it - they are not very expensive.

Shut off the water heater, then open low point drain and faucet to re-establish the air chamber in the water heater.If this doesn't solve problem then, The pressure relief valves give out. You may swing by your local hardware store and get a new one. Read tag on your current one so as to get the correct one.

Is it possible that it's an issue with the thermal cut-off switch?or the thermostats?

Oh, and another issue I had with our water heater, before this present issue, happened last week. Just wondering if the two issues could be related. Last week the plastic drain plug failed. I came outside and found water leaking from around the drain plug. The head of the plastic plug was loose from the base of the plug and easily broke off leaving the threaded portion stuck in the water heater drain hole threads. Of course I lost most all of the water in the water heater during the removal of the old plug and installation of the new plug. Could this speak to the need to follow the suggestion that I open a low point drain and re-establish the air chamber in the heater?

No, if you lost a gallon or more out of the water heater you are good.

Atwood Water Heater | Good Sam Community

16 Replies

Dick_A
Explorer
Feb 16, 2015
Moved from General RV'ing forum.
golfknut
Explorer
Feb 15, 2015
Our T&P relief valve still starts to drip after the water heater heats up. I have not replaced the valve.....yet.

I was wondering how do I know the water heater isn't over-heating the water and the valve is operating the way it's supposed to?

Could a bad thermostat cause this issue?
golfknut
Explorer
Dec 30, 2014
The pressure relief valve lever IS in the open position as I was in the middle of going through the procedure to re-establish the air gap in the water heater.
enblethen
Nomad
Dec 29, 2014
Yes, the lever indicates the valve is in the open position. This is not correct for proper operation.
gdweb
Explorer
Dec 29, 2014
if im seeing the picture correctly, your relief valve is in open position. lever should be down, not extended out
enblethen
Nomad
Dec 29, 2014
That came out of the T&P valve. It is a thread protector. No big thing!
golfknut
Explorer
Dec 29, 2014
I completed the steps to replace the air gap in the water heater as outlined in the post from pulsar .
I turned the water heater back on when complete for about 15 minutes and water dripped out of the relief valve again once the water heated up.

A few days ago, when I first noticed the water dripping down the outside of the motorhome, I opened the water heater access panel and found a small plastic orange sleeve laying in the bottom of the water heater panel area. See the photo below.
What is it and where did it come from?
Bamaman11
Explorer
Dec 29, 2014
I noticed my home hot water heater had a pressure valve popping off from time to time, but the amount of water expelled was maybe 8 oz. It could be a product of water expansion from heat or from quick pressure changes when faucets are opened and closed.

My plumber said that modern hot water heaters should really have a small pressure tank mounted on the water lines.
Old-Biscuit
Explorer III
Dec 28, 2014
T&P Relief valve......

Glad to see someone posted the info from manual about air pocket.

Water is one of those fluids that expands when frozen AND when heated.
Water can not be compressed so the air pocket controls the increase in pressure when heated water expands.

Using the T&P to re-establish air pocket is correct method.
Removing the drain plug is a great method for draining WH to flush etc.
1rickw
Explorer
Dec 28, 2014
You should be taking the plug out maybe 2 times a years to flush out the water heater. It will build up a lot of deposits. You can buy new plugs. When you do remove the plug, be sure that the heater is turned off, and don't relight until it refills. Also, this will give you a new "air gap" which you need so the overflow doesn't leak. Mine drips every time I turn it on to heat the water. I have just gotten used to it. You can also buy a rinser for your hose to help clean out the buildup of deposits.