Atwood 6 gal propane water heater not lighting

[OldGuyOnTheRun]

Hi. I am relatively new at this, bought my 2000 Itasca Spirit a year ago. Just finished a week of dry camping in AZ. The water heater worked several times for showers but then last day it would not light.

1) There is plenty of propane, fridge & stove work well.
2) There is power to the unit.
3) When I inspected it, the connecting screw was missing for the green grounding wire supposed to be fastening the flue to a supporting bracket. I added a correct size screw and it still would not light. i.e., it has good ground now.
4) The 2amp fuse on the circuit board looks good.
5) When I turn on the WH switch on the panel in the RV, after a few seconds I hear a click then silence and the light on the panel comes on. I think that is a "did not ignite" light
6) Stuck my butane lighter into the burner tube next to the spark wires. My wife hit the switch & when I heard the click I clicked my butane lighter and burner lit and burned fine.


Not sure where to go from here. I'm thinking it may be the thermal cutoff or the circuit board.


Any suggestions for further troubleshooting or repair would be appreciated. Thanks.

Alan

 

[Lou Schneider]

Sounds like the spark igniter isn't sparking.  One click is the gas valve opening, which you verified using the butane lighter.  There should be multiple smaller clicks from the spark jumping the igniter gap until the fail light cycles on.

Make sure there isn't a piece of rust or other debris shorting out the electrodes, you need a gap for the spark to jump and light the flame.

If this doesn't help, you may have a bad igniter coil on the circuit board or a bad high voltage insulator on the electrodes shorting the voltage to ground before it reaches the spark gap.

You can see if the circuit board is producing spark voltage by removing the high voltage wire from the board and attaching a wire to the high voltage terminal.  Bend the wire so it's end sits about 1/8" from a grounded piece of metal, then start the water heater and see if you get sparks from the end during the startup cycle.

Don't hold the wire while doing this or you'll get a shock, even through the insulation.

 

[Rene T]

Try unplugging the plug going to the circuit board and clean the plug contacts. Using a eraser on a pencil works good. Then plug it in and unplug it several timers to clean the other half of the connections.

 

[TonyL]

Sorry, just seen this post. Most probable cause is the ignition probe. Remove from the burner, turn OFF the gas, try and wedge the earth terminal of the probe to a good metal point inside the heater or hold it there with insulated pliers. Get someone to turn on the heater and see if it sparks, if not remove the lead from the probe and hold that with pliers next to a good ground. if it sparks, probe is faulty, if not, more than likely it is the ignition transformer or the PCB if it is combined.
Regards
TonyL

 

[sc4668]

I agree with Rene that is what fixed my water heater and has been working fine last three trips.

 

[NY_Dutch]

Sorry, just seen this post. Most probable cause is the ignition probe. Remove from the burner, turn OFF the gas, try and wedge the earth terminal of the probe to a good metal point inside the heater or hold it there with insulated pliers. Get someone to turn on the heater and see if it sparks, if not remove the lead from the probe and hold that with pliers next to a good ground. if it sparks, probe is faulty, if not, more than likely it is the ignition transformer or the PCB if it is combined.
Regards
TonyL

There's no need to remove the electrode to see if there's spark. The spark can be both seen and heard with it in place and working. Cleaning the contacts as described above has fixed many similar problems with RV water heaters, furnaces, and refrigerators. It takes very little corrosion to interrupt the millivolt signal levels used to detect the flame.

 

[8Muddypaws]

Dutch

It lit and burned fine when ignited by the butane lighter.  Probably not the flame sensor in that case.

A few seconds after the gas valve opens you should hear the sparks.  Several of them in rapid succession.

Typically I?ve seen the igniter cathode too close to the anode, too far, or as has already been stated the ignition circuit is just not working.

 

[NY_Dutch]

Dutch

It lit and burned fine when ignited by the butane lighter.  Probably not the flame sensor in that case.

A few seconds after the gas valve opens you should hear the sparks.  Several of them in rapid succession.

Typically I?ve seen the igniter cathode too close to the anode, too far, or as has already been stated the ignition circuit is just not working.

Ahh, good point, I forgot about that... So I'll just caution that any spark gap adjustments should be made by carefully bending the ground electrode. Bending the live electrode can easily crack the ceramic insulator.

 

[OldGuyOnTheRun]

Wow. Lots of good information and suggestions. I'll get busy tomorrow and let you know what I find or do.

Thanks,

Alan

 

[OldGuyOnTheRun]

OK. I cleaned all of the connections to the circuit board, pulled out the sparking unit, checked it out. I suspected the probe as the ground side was somewhat loose in it's welded connection to the bracket.

So I ordered a new probe, installed and tested for lighting and no joy, still no clicking & sparking. So I am left with ordering a new circuit board.

QUESTION...  my Atwood 6 gallon, gas only, owners manual shows the circuit board part number as 93865. The one most similar on Amazon is pn 91367. Is 91367 a replacement board for 93865?

Thanks again.

Alan

 

[Gizmo100]

Is this the one you need?

https://www.amazon.com/Atwood-93865-Potted-Circuit-Board/dp/B0007XU4EC/ref=sr_1_1?crid=3KD0KQ7MHIOHF&keywords=atwood+rv+water+heater+parts+93865&qid=1551985481&s=gateway&sprefix=atwood+rv+water+heater+parts+93865%2Caps%2C209&sr=8-1

 

[Lou Schneider]

If you're going to replace the circuit board, I'd get one from Dinosaur Electronics.  They cost less and have a reputation for being better built and more reliable than the OEM boards.

Once you find the correct board, check Amazon for availibility.

 

[NY_Dutch]

I agree with Lou on the Dinosaur boards. Their UIB-S ignitor board will work perfectly with your Atwood water heater. I recommend getting the adapter plate and cover as well. Amazon has both...

https://www.amazon.com/Dinosaur-Electronics-Universal-Ignitor-0310-1300/dp/B0002MG2IK/

https://www.amazon.com/Dinosaur-Electronics-2TABMOUNTK-Tab-Mounting/dp/B00DPJ2PB0/


I keep a spare UIB-S on hand since it also works with our two Atwood furnaces and other brands and models.

 

[OldGuyOnTheRun]

I ordered the Dometic board before I read your messages. Thank you for the recommendation. I'll get the Dinosaur board when this one quits.


So, the board is installed and the unit now ignites fine.

I have little experience with using the RV water heater over time. When I use it, should I turn it on a half hour before a shower and just leave it on until I no longer will need hot water? I.e., will it cycle on and off keeping its rated temp? Should I run it for half hour then turn it off ? I take navy showers.

How do you use the 6 gallon water heater while dry camping? And what shower head do you have installed in your shower?


Thanks again to everyone for your comments and help.

Alan

 

[8Muddypaws]

A half hour sounds about right.

Oxygenics is the best we?ve used.  Good shower even when boondocking.

 

[Lou Schneider]

I can hear the flame from my water heater inside the RV.  It takes about 20 minutes to heat a tank of water from dead cold, after that it will cycle on and off as needed to maintain the temperature.

As to whether to leave it on or turn it off after your shower, that's up to you.  I find I can turn off my water heater after my shower and have plenty of hot water available for my other needs (dishes, etc.) until I turn it on again the next morning.

 

[Old_Crow]

I'm with MuddyPaws on the Oxygenics shower head, but since we live in our coach full time, we leave our water heater on all the time except when filling the propane or leaving the coach for a while.  You'll find that you get as many different opinions as answers on that question.

 

[OldGuyOnTheRun]

thanks again all.

Until my next issue....happy trails.

There is always something in an older RV. I may need to discuss a leak in my cabover... noticing some new rust in the front , lower metal corner seals. This has been a really wet winter in So Cal.

Alan