Atwood Water heater

[ischua]

The Atwood water heater on my Mh (original equipment) failed to shut down today.Cleaned and scraped all contacts still won't shut down. I have spent most of the night trying to read up on repairs with not much luck on older models What should I be looking for? Thanks

[Martind4]

My guess is that a thermostat failed. Ours has the thermostat(s) for gas operation on the front of the WH. The thermostats for 110V operation are on the backside of the WH.

Did it fail to shut down on electric or gas? Did the temperature/pressure valve release or how do you know it failed to shut down?

[ischua]

This is gas only unit 6 gal. It ran for 45 min to an hour and the pressure relief valve started to open. Ran some water and tried again 20 min later PRV starts to drip and I shut it down. Don't ever remember it taking so long to shut down.

[Martind4]

Does it have an adjustable thermostat, manual ignition with the red knob on top with "Off, Pilot & On"?

If so, the gas control valve has a "stinger" (thermostat) that extends into the tank. Disconnect the gas line and burner assembly and it will screw out of the tank. It might be caked with minerals or corroded and not sensing water temperature properly.

[ischua]

no knobs and electronic ignition Jade??

[Martind4]

We're at the limit of my knowledge of water heaters, maybe somebody else can join in.

Can you post a picture of it?

[Dave78Chief]

What style of unit do you have?

There are Pilot amd Direct Spark Ignition (DSI) models.

A DSI model will just have a On/Off switch inside the rig.

The Atwood Pilot model has one of these style of control knobs


For a pilot model, the temperature sensor bulb is part of the gas valve (the copper bulb on the left side of the valve in this picture).


You might be able to clean the bulb as Martind4 suggested. Otherwise you have to rplace the valve. Pilot models do have adjustable temperature settings.

DSI models are controlled by a circuit board that monitors temperature / High temp cut-off sensor pair. Most are not adjustable. Some models have the sensors mounted on the rear of the unit and look like this:


Other models have them mounted to the front of the unit and look like this:


Either the control board or the temp sesor could be defective on your DSI model. Most likely the control board because the ECO is a high temp safety cut-off (180 degree) and would shut your unit down at high temp if the normal t-stat did not shut down at the approximate 140 degree set point.

Atwood Water Heater Service Manual: http://manuals.adventurerv.net/Atwoo...er-Service.pdf

Dave

[ahicks]

I would offer that some water dripping from the pop off valve is not too unusual? Actually it's pretty likely on most systems as unless the system leaks, there's no place for the expanding water to go as it comes up to temp.

Turning the faucet on would relieve that pressure obviously, but if the burner continues to run, the water will continue to expand.

When you turn the hot water faucet on, does the water seem unusually hot?
Where is your thermostat set?
Is the flame roaring like it normally does, or does it seem a little quieter? Wondering if the reason it's running longer might be due to a dirty/obstructed burner.

[Dave78Chief]

The unit not shutting off would not be a weeping problem. As far as weeping is concerned, here is Atwoods information on how to solve that from page 26 of the link I posted (performing the procedure at least will rule that out as the OP's issue):

PRESSURE-TEMPERATURE RELIEF VALVE

Weeping or dripping of a pressure-temperature relief valve while the water heater is running DOES NOT mean it is defective. This is normal expansion of water as it is heated in the closed water system of a recreation vehicle. The Atwood water heater tank is designed with an internal air gap at the top of the tank to reduce the possibility of weeping and dripping. In time, the expanding water will absorb this air. To replace the air follow these steps:

Step 1:

Turn off water heater

Step 2:

Turn off incoming water supply

Step 3:

Open the closest hot water faucet in the coach

Step 4

: Pull handle of pressure-temperature relief valve straight out and allow water to flow until it stops.

Step 5: Allow pressure-temperature relief valve to snap shut, turn on water supply and close faucet.

Dave

[ischua]

As for Dave's post

1 Looks like a "Jade " I have a remote switch inside so DSI

2 The lower most photo is what I'm seeing with thermal cut-off(?) on brown wire

3 Flame roaring like normal

Don't know if the water temp got to 180 deg before I shut it down
Thanks for the help

[Dave78Chief]

You have conflicting statements in your response.
A DSI model would not use a Robertshaw or White Rodgers (Jade, ITT) pilot gas valve. So if you do have a Jade control yours is a pilot model.
Jade looks like this:


Robert Shaw looks like this:



Both of those controls have a pilot light you would manually light with a match or a lighter. A DSI model "does not" require you to use a match or lighter to manully light a pilot. If you do have a "Jade" then please note the temperture adjust lever I point to inthe picture. You may have inadvertantly moved that resulting in higher temps.

Atwood also built dual souce (gas and electric) Pilot models that have a 110VAC electric element inside. A dual source would have a On/Off switch inside the rig for the electric element. Control of the gas and electric sides are completely seperate on pilot models.

A DSI model is totally automatic which generates a high voltage spark to ignite the gas. There is no pilot light. The On/Off switch inside provides 12VDC power to the control board.

When you open the outside door of the unit there shoild be a sticker that says what model you have. Knowing that number would help determine what you have.

I use a meat thermometer to determine hot water temp. I let the heater warm up then draw some water from a tap into a cup. Read temp from thermometer. RV water heaters run hotter (125) than home heaters because of the smaller tank size.

Dave

[ischua]

The rain has finally stopped and I went and took a good look.
As to the conflicting statements ....Yes....

The lower most photo is what I'm seeing with thermal cut-off(?) on brown wire
E.C.O. T'START Still yes
DSI .... still yes
Jade .....not..... There is no temperature sensor bulb on gas valve. But has 4 wires attached otherwise not attached/into to the tank in any way only gas

[Dave78Chief]

As long as you are positive it is getting to hot then for a DSI model it can only be a bad thermostat. 12VDC B+ voltage is supplied to the control board via the thermostat. When the thermostat opens, due to reaching the set temperature, it turns off the 12VDC B+ voltage to the control board shutting down the unit (essentially does the exact same thing the Power On/Off switch does).

Dave

[ischua]

Thanks

I will remove the thermostat and test it now that I know where it is.