Last night, I noticed that my Atwood water heater (electric ignition) wasn't lighting. I'd hit the ignition switch and nothing. The water was around 40C (104F). It was definitely getting power.This morning, the water heater turned on like normal, heated to 40C, and shut off. I couldn't get it to relight until the temp went down several degrees.This happened again tonight. I can't get the water above 40C, which is barely tepid or lukewarm, definitely not hot enough for washing dishes much less taking a shower. It normally goes to at least 46 or 47F (115F); hot enough to scald myself.I put in a new circuit board three years ago and I do maintenance like cleaning the flue, checking the probe, and cleaning all contacts at least twice a year.Any thoughts?Thanks,Rae

You didn't set the temp switch back by mistake??

Hi,The high limit thermostat has failed or is out of adjustment (I do not know if they are adjustable or not).

Mine doesn't have a temp switch as far as I know. The manual says "Electronic ignition: light unit by pushing button inside the coach. Water temperature is non-adjustable."I'm looking at the wiring diagram and there are a few temperature related parts on it:-fixed temperature control thermostat-thermal cut-offI should be looking at which one of these?Thank you so much for the quick reply!Rae

Hi Rae,If you have an ohm meter check them both. I don't know what the value should read, unfortunately.-fixed temperature control thermostat-thermal cut-offChris Bryant maintains a web site for trouble shooting water heaters and is very helpful.

Oh, I can find that out. Wouldn't have thought to check the resistance. Thank you so much!Rae

Atwood water heater heating to tepid then shuts off

14 Replies

pianotuna
Nomad III
Aug 09, 2013
Hi Rae,

See my private message.
TravelingRae
Explorer
Aug 09, 2013
It's still not acting perfectly. I've got the water up to 45C now, but that's still not hot enough and I had to coax it to get that high by removing and reattaching one of the leads to the thermostat.

Rae
pianotuna
Nomad III
Aug 09, 2013
Hi Rae,

Sounds like there may have been a corrosion problem.
TravelingRae
Explorer
Aug 09, 2013
Before replacing anything (considering it will take weeks to get anything sent here), I removed all the leads to which arrows are pointing in the above picture. Then, I cleaned and reconnected everything and WHOOSH, the water heater started right up! The water's now almost 5 degrees C hotter than it's been all week!

I will order replacement parts, but looks like I bought myself some time.

Rae
TravelingRae
Explorer
Aug 09, 2013
Oh, you guys are GREAT! Thank you!

A guy who has the same rig as me (a rarity) just posted to my blog to confirm the part number I need. The picture was the missing piece.

I'll go with whatever I've got now. I have a little thermometre that's attached to my water heater to monitor the temperature. I have it set to beep when it gets to my ideal water temp. I can then shut off the water heater (save propane and power) and grab my shower. Works great. I got the idea from Andy Baird.

Rae
Chris_Bryant
Explorer II
Aug 09, 2013
Here you go-

The thermostat and ECO are behind the foam cover- a new cover is included with the replacements in Atwood p/n 91447. The adjustable are nice, but most people wind up setting them to the same temperature as the 140 F fixed stats.
pianotuna
Nomad III
Aug 09, 2013
Hi Rae,

If you have to replace I'd go for the adjustable unit.
TravelingRae
Explorer
Aug 09, 2013
Definitely not the shower handle issue; done that before. :) By-pass valves are good; been down that road before, too.

I did more research about the thermal cut-off and agree that's likely not the issue.

So that leaves the T-stats. You gave me some good info on how to find them (getting to them is going to be interesting).

Thank you so, so, so much!

Rae
Old-Biscuit
Explorer III
Aug 08, 2013
The thermal cutoff is a one-shot diode that trips due to flare back from burner (190*F)
Heater will not light if thermal cutoff trips until replaced.

The t-stats are fixed temp set points
Normal opens at 140*F and the ECO (Energy Cut OFF) opens at 180*F

So with just tepid water either the normal t-stat is opening early OR you have cold water mixing with hot water (water heater bypass valve open, shower turn off via handle vs knobs)

Check the valving
T-stats are 'normally closed' then 'open' when set point reached.
T-stats need to be tight against tank wall
T-stats terminals can get loose/corroded inhibiting good contact
New set (normal/ECO) cost $15
There is also an 'adjustable' one that can be used in place of 'normal' t-stat (110*-150*F)
TravelingRae
Explorer
Aug 08, 2013
Oh, I can find that out. Wouldn't have thought to check the resistance. Thank you so much!

Rae