Atwood Furnace problem

That's what they told me and I have no reason to doubt it.

I verbally informed them going in that the unit had to go through a normal cycle. (No manual turning it off and on, leaving the temperature control on the thermostat alone.)

Once it had gone through its routine of normal... then sometimes working on the 2nd or 3rd try... then failing to lite at all... it would "rest" for approx. 12-20 min., then do this over again. It did this from the time it was first installed.

I should have had it all in writing and taped it to the unit when I left it at the Service Center. I'm sure they didn't understand the above due to the fact that after they kept it overnight I got an email stating that the unit fired up, first try, from sitting all night. It always did fire up normally after a "rest."

The strange thing about this one is that it apparently worked fine on the bench?

Great! Glad you found it and thanks for reporting back

Atwood, every time I have called them have been very helpful. They will talk to a customer direct. They get my business next hands down. Not all brands of RV appliance do this.

I called the Atwood Center in Indiana and told my story.

They advised replacing electrode and sent a new one.

I switched it out yesterday and the furnace now runs as it should. The Atwood Techs (All 3) were helpful and patient.

Its been a 2 month haul going through the trouble shoot and process of elimination.
I now own two working regulators, a manometer and a voltage/amp meter and can remove and install this furnace in under 1/2 hour in the rain.

I now know that the gas pressure should be checked BEFORE you buy a new regulator.

I now know that you should completely remove the electrode from its mounting bracket to visually inspect it. After replacing the electrode I see a very slight sparking discoloring where the ceramic goes through the mounting bracket and I suspect this is the problem. Its located where it is impossible to see without removing it from the sheet metal mounting wall.

I'd like to thank all of you who took the time to help me out.

1996 30' Dutchman, lived in and never used as a travel trailer. Both fridge and WH propane lines capped when new and are 110 electric only. Previous owner, a good friend, was a Heating and Air conditioning pro in Sacramento. Died 6 years ago. R I P.

LED indicates Ignition Lockout.

Manometer, not gage, shows 11" at Stove and Fridge with burners lit or not, Water level is 5 1/2' + and 5 1/2" -, furnace running and heating (when it decides to fire up.)

Ignitor gap is exactly 1/8" and ceramic looks as good as new.

Wires all look good, connections are clean and tight.

I think the board is failing. Will not fire up even once in awhile now.

I agree with Old - Biscuit on his list.

When I go into troubleshooting these kind of things, I think through what is and what is not working then go prove them out which you do not know.

Reading the responses you need to rule in or out a few things.

Not enough spark or not enough gas is an indication from what you describe. If you hear the igniter clicking and no fire, you can rule out the over temp shut down switch as it would not be trying to ignite if you are over temp during that event. That said, the overtemp will shut it down, but if it is clicking spark, your past this. Do not loose site of this as there may be more than 1 problem.

The sail switch was mentioned, this is in the main saftey circuit. If the sail switch does not make, then the unit will not attempt to run the igniter. When the sail switch goes flaky it can drop out the flame. You need to keep in mind, is the igniter click or not?

The regulator, since you are measuring pressure and reporting 11" WC, are you on a gage or a manometer? I do not know how fast your gage is, if it is a gage but if it is a manometer, have it hooked up and light all stove burners and hot water heater on gas. Now stare at the liquid line, when flowing it should be at 11" maybe a little more. Not 10 or under.

Now while looking right at the liquid line on the manometer, fire the furnace with the rest of the appliances on gap and burning. When you hear the gas valve clunk (if you can) but for sure listen for the clicks of the igniter. The liquid level should at least bounce until the flow stabilizes rather quickly. If there is no wiggle, or very little wiggle, then gas may not be flowing or very little. These cheap regulators are for sure going to create an upset when the full gas valve opens on the furnace. Your looking to see that a large draw is actually working. This can be why the dealer tested OK you you not. He was on a different regulator.

Point is, if the igniter is working (sparking) and you have gas it should try and fire. It might not stay lit but if you are short on gas there should partial fire. If you can hear the clicks, then the igniter has to have enough upmh to jump a gap unless it is jumping somewhere else (shorted wire). A gap that is not a long enough distance may not have not enough energy to light. It takes more energy to jump the right gap. Old Biscut was talking about this

You have to sort out if gas is flowing. There may be a clogged line, or bad gas valve if the regulator is working. The regulator needs to hold 11" WC when all gas is flowing. There can be a momentary upset when the valve opens but should rise to 11"WC quickly and hold. I believe the maximum lock up pressure allowed is 14 "WC when you shut everything off so a 12" when full flow is not totally bad.

Hope this helps and report back what you find

John

RDWhipp wrote:
Return air has more sq. in. than specs ask for.
Electrode gap set at factory. It's a brand new unit.
Two of 3 burners on and Furnace on. (Electric water heater.)
Always fires up correctly after a rest, works fine for 1-2-3 cycles then things go down hill.

Gap set at factory doesn't mean it is correct or in proper position

Electric water heater.....heard of gas only but not electric only.

When measuring propane pressure....turn as many gas appliances on as possible. Better indicator of how well regulator responds to demand

Return air may have more area than spec calls for...but if anything is blocking/obstructing it will cause issues

What 'codes' are being flashed

Fault LED Indication

Internal Circuit Board fault Steady on, no flashing

Limit switch/Airflow problems 1 flash with 3-second pause

Flame Sense fault 2 flashes with 3-second pause

Ignition Lockout Fault 3 flashes with 3-second pause

Return air has more sq. in. than specs ask for.
Electrode gap set at factory. It's a brand new unit.
Two of 3 burners on and Furnace on. (Electric water heater.)
Always fires up correctly after a rest, works fine for 1-2-3 cycles then things go down hill.

Couple of things.......

Blocked/obstructed return air.....sitting out on bench it is out of cabinet

Spark electrode position/air gap........should be 1/8" and directly over burner slot

Pull connector on board.......use pencil eraser to clean contact surface. Make sure pins in connector are making good/tight contact on board

That gas measurement..........11" WC at stove
Was that with just one burner..........or all burners, fridge, water heater.
Best practice is measure with at least 50% of gas appliances in service.......the more the better the measurement of how regulator responds to demand.

Got it back and installed Thursday. Same problem.
Service center found no faults and said Board checks OK.
I again triple checked all wiring and voltage. OK.
Propane lines are clean.
Checked Propane pressure at stove with manometer and reads 11".
I still suspect a board problem all things considered.