Atwood water heater continually igniting and boiling water

[tiinytina]

So... last few trips out our water heater has been acting up.. not starting (checked for cobwebs), checked for power at unit, and that was hit or miss so installed a new in cabin switch. Now it starts most of the time but if you go outside you can hear the electronic ignition clicking and sparking. The flame never turns off and the water is scalding.....

So.. yes the thermostat needs to be replaced which will override the boiling issue... but the question is if the thermostat will make the igniter stop trying? Pat and Brad pulled the spark cable from the ignitor and the sending unit was still sending current spurts.... so don't think its a bad igniter but.... $43 to replace that.

The tank on this unit is fine, obviously getting LP and power...  It is an Atwood 6gal LP with electronic ignition.  replacement new is $500.. ouch

Thanks!
Tina

[DaveVA78Chieftain]

Tina,
I can probably help but I need to know the specfic model number (i.e: GC6A-8E).  There a few different designs.

1)  First clean all connections (control board, ECO, thermostat, gas valve, etc.).  Corrosion is a known issue.

2) For early versions, power to the control board is routed through the thermostat, so replacing that will not solve the sparking problem.  Later models did not work that way but the thermostat would not cause a continious sparking problem in those either.

3) Control board should try to light the furnace for 6-8 seconds.  If it does not sense the flame at that point it is supposed to go into lock out.

4) Make sure electrodes are clean and adjusted properly.

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

My initial guess is the control board is defective.

Dave

[jkilbert]

when you start looking. a company called Dinosaur Electronics makes a complete line of igniter and control boards for most all RV appliances. it seems that they are one of the bigger suppliers of these kind of replacement parts. here's a link for them...

http://www.americanrvcompany.com/Dinosaur-Boards-_c_372.html

[tiinytina]

Its a G6A-4E 1987 model as far as I can tell as seems original to rig.  Patand Brad were thinking it was the control board as well because pulling the sparkplug like fitting off of it it was still sending signal to igniter....

The thermostat fell off in my hands. The guys had pulled off the wires from them to see if that made any difference but they are not sturdy so the "Brown" wire side is now not connected. The thermostats on this seem to be mounted on flattened springs which "screw" into ports through shielding to sit on tank surface.

I will open control board area and see if there is anything obvious there... could be spider etc got in and nested shorting things.. ok or.. ya the unit is 25yrs old and to date I've never opened that up as it seems sealed...

Found a new one on AdventureRV.net for $376 including shipping...  New board and new thermostat would be about $100 and may not solve the issue... thats what I'm hemming and hawing over...

tina

[DaveVA78Chieftain]

Wiring diagram for the 2 versions is on page 24 of the manual link I provided above.  The list of units indicates yours is the 2nd diagram.  The real difference between the versions is that the ECO & Thermostat is mounted on the rear of the tank for the early model and are 2 sepereate parts (no longer available?).  The newer one, that yours is listed under, has the ECO & Thermostat mounted on the front with the rest of the components (control board, Gas Valve, etc).  Based on the diagram, you would be replacing the thermostat and ECO as a unit (both mounted to the same plate).  So, given you have already replaced the switch, replacing ECO/Thermostat (91447) and the control board (93865) only leaves the gas valve and electrodes.  Toss in the electrodes (93868) and everthing that could possibly cause this has been replaced (for around $160?).  OK, the wires are stll there but that should be no big deal.

The real enemy of the water heater is tank corrosion.  Sediment in the water reacts with the aluminum causing the aluminum to corrode.

If you do replace the unit, then think seriously about a gas/electric version.   Wiring in 110AC is not hard.  The 1500W element draws 12.5 amps of 110VAC.
Here is a used DSI Combo unit for basically the same price as the one you are reffering to.
http://www.ebay.com/itm/ATWOOD-6-GALLON-GAS-ELCTRIC-RV-WATER-HEATER-GC6AA-10E-/350495225088?pt=Motors_RV_Trailer_Camper_Parts_Accessories&vxp=mtr&hash=item519b24b500
Even though it is used it has to be a late model because of the '10E' at the end.  Besides, it looks to clean to have been installed very long (obviously pulled from a wrecked RV).  Wiring for this one is a wee bit different (see page 25 on the Atwwod manual link above).  Even the one you are looking at (DSI only) is wired a wee bit different (bottom of page 24).  A new switch may also be required.

I know, decisions, decisions.   D:oH!

Dave

[RedneckExpress]

If water heater is an original atwood, its time for a new one.  I just got done doing a water heater upgrade on my neighbor's 20 year old Southwind.  Deleted the 6 gallon DSI Atwood for a higher refresh rate 10 gallon pilot light Suburban.  Got the 10 gallon for $315 off of PPL motorhomes and the new face plate for $50 and managed to get their $7.99 shipping special on the whole deal.

[tiinytina]

I can get the new thermostat parts locally for $24  ($10 online with shipping)... easy replacement, is on front just flat springs that screw through face plate to contact tank.   Control board will be different issue if that is the case. Won't have time to mess with any of it until maybe Sunday.  Have electrically inclined neighbor who can test the control board for us.... from the link Tim provided no clue which one would could replace...

Downloaded the schematics and trouble shooting for the unit (thank you)... now to find time and daylight together.....

Figure we can do the control board testing wtihout replacing the thermostat... then if that is bad.. time to decide to fix or replace... never had too much problems with the unit until this season but it has been the season for everything to go wrong after 5 trouble free years... ... 

Wiring will be pretty simple (hoping for easy button) as electrical enters RV right in same spot..

Tina