sonuvabug
Mid-Western, ON Canada
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Our hot water heater works fine ... but it won't shut off when it gets the water hot. Twice the safety valve released and spewed out the hot water at our campsite.
I suspect there is a sensor that is not working properly causing this to happen. Is it an easy fix (i.e. locate and replace the sensor) or does the whole whater heater unit have to be replaced?
Not sure what I'm really looking at when I pop the hot water heater panel nor am I sure what to do as a next step. Help! ~ bugjr ~
1993 Glendale Royal Classic Ford E350; 460EFI; E4OD;
Drives 26'/Sits 29' with rear slide; Michelin LTX/M&S; New Monroe "SC2955" Damper & anti-sway bar bushings; Rebuilt Rear Leafs; Bilstein B46-1613/14; Should be "pristine" by 2009 or 2010 or ... 
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rrupert
NW PA (Oil Heritage Region)
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Joined: 02/26/2005
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First, look to see if there is a temperature setting dial on the WH. It my need turned back to a cooler setting.
The thermostat may be faulty, they are usually replaceable. Your best bet would be to take it to your dealer for replacememnt.
Joyce and Rich
2005 HiLo 1705T
2007 Fleetwood Sun Valley Popup (Our 5th PUP)
2007 Toyota Tacoma Crewcab
Amatuer Radio K3EXU
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JFG
TN
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Do you know the make model of your hw heater?
Fred
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KEBrown
Kansas
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The pressure regulator is doing what it's suppose to do and be glad it is or things could get ugly, something is wrong... air trapped in the tank, or the water is to hot (thermostat)... those are about your only two reasons why it would pop off. Hook up your city water and open the drain on the water heater and purge the unit. A new thermostat should be like $20. IF it's a bad pressure regulator, those are only about $30, if you can get it off, heat tends to "secure" them quite tight. Even at $50 in parts it way cheaper than $400 for a new one and the dealer will probalby charge you $50+ just to "diagnose" it.
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DAS26miles
San Fernando Valley, California
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The thermostat disk may not be making contact with the tank. Do you have an Atwood? If so, look at the center top and you will see a clip hold a spring and disk. Make sure the disk is making contact. If you have one with dial settings A to F, set it back towards the A. I originally had the disk and the temperature in the shower was 150 degrees. I replaced it with a dial thermostat and keep it set at "A". The temperature is now 120 degrees, plenty hot for us.
2004 Class C Winnebago Minnie 22E
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sonuvabug
Mid-Western, ON Canada
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Thanks all for your ideas and suggestions.
I recall it being an Atwood brand, 6 gal tank but I'll check out the brand, model number tonight to make sure. Although I know nothing about these things, the thermostat and/or sensor diagnosis sound quite logical.
Also, I do not recall there being any kind of a thermostat dial for setting the temperature ... either on the inside of the rig or behind the outside panel. In fact, I do not recall there being a "thermostat" in the classic sense at all.
What I have inside the rig is an on/off switch with a red "on" light directly below the sink which turns on the water heater when engaged.
Then there is all the "stuff" behind the outside panel. i.e. drain plug, flame tube, electronic ignition module, safety valve, and about three wires plugging into the side of the water heater tank unit.
I'm thinking since it still heats the water very well, that part of the water heater is functioning fine. It's just the upper temperature sensing/cut-off functionality that isn't working properly.
I'll post again once I take a closer look.
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Oldfordman
Marysville, WA
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In reading you post you indicated "campground". I would assume you were plugged into shore power. I had the same issue with an Atwood 6-Gal heater several years ago and had to replace the thermal limit switch. It is a small round "button" with two spade lugs for the wiring. It MUST be in contact with the heater tank in order to function. Otherwise you have a 6 gallon "Tea Kettle" and it will continue to boil, blowing steam out the T/P (Temp/Press) relief valve.
Your cure may be as simple as just making sure there is no insulation between the thermostat "button" and the tank.
Life is full of choices. I choose to have fun!
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JFG
TN
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The thermostat is a small round disk with two wires running to it. It mounts to the side of the tank. Any RV reapir facilty should have one in stock.
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jetcare
Mission, TX
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Bugjr,
If the water heater (Both Atwood and Suburban) is operating on 120 VAC, here is how they work.
120 VAC (hot wire, black) comes from your ON/OFF Switch in the RV to an over temperature limit switch called the ECO. The switch opens if water temperature is over 170-180 degrees F. If the ECO switch is closed (normal condition) then 120 VAC goes to the thermostat switch. The thermostat opens when water temperature reaches 130-140 degrees F. Your water heater cycles OFF and ON using the thermostat switch. When the ECO and thermostat switches are closed, 120 VAC goes to the heating element. All the above discussion involves the black (hot) 120 VAC wire. The white neutral wire goes directly to the other terminal on the heating element.
Note: Unless you have a brand new Atwood, you have two sets of ECO’s and Thermostats. The ones you see from the outside of your RV are for the Propane. The electric system ECO and thermostats are on the inside of the RV where the 120 volt heating element wiring is connected.
With all this said, your water heater must be reaching 210 degrees F. if the pressure-temperature relief valve is spewing hot water unless the P&T relief valve is defective or has junk under the seat.
Here is what I would do. Turn on the water heater until the P&T relief valve begins to spew. Use a thermometer (candy?) and check the water temperature coming out the faucet nearest the water heater. If the water temperature is over 205 degrees F., I think the P&T valve is working properly and both the thermostat and ECO sensors are not opening which is highly unlikely. A more probable cause is that for some reason they are no longer touching this side of the water tank or the insulation blanket (small black piece of foam glued over the outside of the thermostat and ECO) has come loose.
If the water temperature is 130-140 degrees when the water is spewing from the P&T relief valve, replace the P&T relief valve or try cleaning the seat by operating the P&T handle 4 or 5 times and see if it will stop spewing.
If you are operating on propane, we need to take a totally different approach.
Matt Harris
A1 Mobile RV Services
* This post was
edited 07/13/08 08:09pm by jetcare *
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sonuvabug
Mid-Western, ON Canada
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OK, my water heater is a 6 gal. Atwood (circa 1992) and as far as I can tell, it is only a propane unit. I see no electrical wires going in or out of it.
Last trip out, nothing worked on it. It wouldn't even fire up like before.
So I opened the outside access door and cleaned every electrical connection (to the electronic ignition board, the ECO and PT? terminals, and the spark wand? (don't remember what this is formally called).
I then applied a corrosion preventing paste on each connection (my out of town B-I-L electrician suggested this). The two discs for the ECO and PT (was does PT stand for) seem to be making good contact with the tank )which I cleaned as well.
Still No luck ...
I'm thinking it's the "motherboard" that is not working properly but unfortunately, my Atwood paperwork/instructions do not provide much in the way of a trouble shooting chart etc.
My gut tells me it's a pretty simple problem ... just don't know where or how to trouble shoot it.
PS - Matt -- WOW ... thanks for your detailed response.
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