Water heater overheating

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Dougie Brown

Dougie Brown

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Joined
Nov 16, 2007
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UK
We have a newly-acquired Winnie Adventurer 37G with a dual gas/electric water heater.  Both sources work the heater, but if we leave either source switched on for more than an hour or so, scalding water starts being ejected from what appears to be a pressure relief valve.

I presume it's a thermostat issue, but is there only one thermostat for both power sources?  If so, what's the job like to change it?

Pics attached.  Thanks.

Dougie.
 

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Dougie, RV water heaters do put out very hot water, and do not have adjustable thermostats. Many times when the T&P valve is leaking, it's because you have lost the air pocket in the water heater tank. There is a procedure for reestablishing the air pocket in the library here, and that is probably the first thing you should try before buying parts.
 
Thanks Dennis.  Our Rexhall back in the UK never heats to the scalding level that this Winnie does, and in fact I would say it's dangerous.  That's what got me thinking a thermostat wasn't working.  So if there is no thermostat, what makes the gas cut off when it gets to temperature?  That's what appears to happen with our Rexhall.

Dougie.
 
There is a thermostat, just not an adjustable one. It's in your first picture where it says ECO T stat. It is simply a spring loaded sensor that sits against the outside of the tank. Our water heater puts out very hot water also.
 
Dougie,

I think it appears you have an Atwood heater. There is a thermostat and thermal cutoff in the unit. The two thermostats that are available, the last I knew, are 120 deg. and 140 deg. I'd try what Water Dog mentioned first but, if the water is over those temps, I would call Lazy Days since you are still under warranty. Perhaps they could send you the parts to fix it. If not, see if they'll authorize Eagle's Pride to look at it. That would be good since they are in the park.
 
Thanks guys.  Jim, there is no warranty - it was "as is" although Sharon & I did a deal to get a full pre-delivery check when the various items were fixed.  I can't guess what the water temp is in degrees, but it's impossible to touch, and steams a lot even on a hot day!  :-\

I'll try a drain-down first & see how it goes.

Dougie.
 
Dougie,

I forgot it was an "as is" deal. There probably is information in our library on that subject. It's easy enough to replace.
 
Dougie, Those two thermostats in your picture, marked "ECO & T stat", need to be replaced. Retail price for the two new stats w/foam sticky cover, is about $16. Atwood part number 91447.

Richard
 
WIthout knowing the make of the water heater I can not tell you how big a job it is.

However This I do know.. If the water heater is an ATTWOOD.. Might take 5 minutes if you do it yourself.. Very easy.  And 4 of them will be reading the directions.
 
Richard - I'd feel much happier replacing the stats due to the crazy-hot water temp.  I've drained and refilled the HW tank but will not check it out until the morning now.

John - Jim reckons it is an Attwood (see above), and Richard with his advice appears to concur.  I'll pick up the parts next week, hopefully.

Thanks!

Dougie.
 
Our Atwood has separate thermostat/ECO sensors for propane and 110V. The electric is on the back of the heater.
 
Jim Dick said:
Dougie,

Check the label on the right side of the heater. It appears to be an Atwood label. :)
Click to expand...
You've gone & disillusioned me now, Jim.  I thought you were good, but you just read the label!  :'(

Dougie.
 
Sorry, Dougie. I was taught to look at the obvious first.  :) If I didn't have an Atwood it might have been harder!

You really need to get out to Yellowstone quickly. We've had snow for three days running!!! Must have gotten at least 4" today!!!!  That will certainly lower the temps for you. :)
 
If the T-stat fails the ECO (Emergency Cut-off) will limit the water temperature, but it will be hotter than normal. I'd bet on the air head problem first, though.

Older Atwoods have separate Thermostats for electric and LP operation. Newer ones have only one for both. I'm not sure when the change took place, but would  guess it is after year 2000 when yours was installed.

120 degree water (the standard thermostat) is scalding hot as it comes direct from the tank.
 
OK - I drained, re-filled and bled.  The water temp remains very high, at 144 degrees according to the food thermometer.  It really is far too hot to touch.  However, after three hours, the relief valve has not activated.  I'll continue to monitor it throughout the evening and switch it off later.  Even it this has cured the blow-off issue, I will still replace the stats.

Dougie.
 
Dougie, If the primary thermostat fails and the water heater is being controlled by the ECO thermostat, it will shut off at about 140? and lock out the control board. The water heater won't re-fire until you cycle the on/off switch.

Richard
 
Richard:

That may be true of the gas side but our Atwood electric heater worked that way for several days until I figured out what was wrong.
 
I can confirm that the board is not being locked out on electric.  I've not experimented with the gas side, but it's academic anyway. I might be lucky with the RV repairers tomorrow here on the resort.  If not, there are a dozen on fleaBay and loads on supplier sites.

Dougie.
 
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