Another Water Heater Question

[BinaryBob]

A puzzling situation. 2 questions.
Atwood Model GCH10A-4E
1.  Last outing was almost 2 months ago. Set up the rig and already the water was scalding hot without turning the water heater on. I've read elsewhere about the possibility of the engine providing hot water through some type of heat exchanger. This is new to me. Can someone elaborate on how to detect if this is heat exchanger is set up? And how to turn it off? The water smelled strongly of sulfur until I ran the hot water a while to flush the tank.

2. I've read numerous complaints that the standard Atwood thermostat is just too hot. I find the water painfully hot. Has anyone had experience with the Atwood Adjustible Thermostat ? Some positive reviews, but some negative that complain that the back doesn't sit snugly against the tank and some modifications need to be made to fit properly.

All advice appreciated!

 

[Mark_K5LXP]

From their website:

Atwood RV Water Heaters -

Features:

    Engine heat exchanger connects to RV's radiator system and heats the water as you drive
        No waiting for the tank to heat up when you arrive at your destination
        Double-tube construction prevents engine fluid from contaminating water

My Itasca has one of these.  I see it as a problem waiting to happen but the engine coolant goes to the rear of the chassis for cabin heat anyway, so the water heater gets warm by default.  I guess too if I ever run out of propane I could run the engine and not have a cold shower.

Mark B.
Albuquerque, NM

 

[NY_Dutch]

That model water heater does have the engine coolant heat exchanger feature. Atwood does not supply the hoses and fittings used to connect the exchanger to the vehicle's cooling system, so whether a shut-off valve was included on your installation or not was a coach manufacturer decision.

I've never installed an adjustable thermostat on an Atwood water heater, so I can't help there.

 

[Gary RV_Wizard]

The "H" in the model number indicates it has the engine heat exchange feature, aka "Motor Aid".

The stink has nothing to do with Motor Aid feature or the thermostat - it's simply a micro-organism that thrives in hot water and stinks. Sanitize your water system to get rid of the microbe.

The standard Atwood thermostat is 140 F., but there is an adjustable version available that can be set anywhere between 110 & 150.

https://www.amazon.com/Atwood-93105-Adjustable-Electronic-Thermostat/dp/B001BZ36HM/

Whether 140 is hot or warm depends on the plumbing in your RV.  The further the faucet is from the heater, the cooler the water gets on the way. It's not unusual to find one faucet is extremely hot, while another further away is fine.  Using a lower temperature thermostat may solve one temperature problem but create another (water too cool in the shower, for example).

An alternative solution is to install single lever faucets that make it easier to mix hot & cold at the faucet.

 

[8Muddypaws]

The ‘Motor Aid’ system does not have a thermostat to limit the temp.  That is definitely a problem waiting to happen.

I thought about installing an adjustable but to do that I’d have to completely remove the WH ‘again’.  I read somewhere (Amazon?) that they have a high failure rate.

Atwood mixes extremely hot water with cold water to deliver 140F.  Seems like it would be an easy thing to put an adjustable valve on the Hot side of the mixing valve.  When my mixing valve got clogged with scale the water got cooler and cooler to the point I had to fix it.

 

[BinaryBob]

Thank you all!
Just arrived at next destination. Did not realize the sulfer smell was unrelated. Thank you Gary. I will sanitize the system. Not too happy with this motor aide system. Will investigate a shut off for it.
Sent from iPhone.

 

[Gary RV_Wizard]

Atwood mixes extremely hot water with cold water to deliver 140F. 

Only in the XT models, which do that to effectively increase capacity. By mixing cold & hot water, a physical 10 gallon heater can produce up to 16 gallons of 140 degree heated water.    The standard models of both Atwood and Suburban have fixed temperature thermostats and do not mix hot & cold water.