Atwood Furnace Won't Light...........

[spudder]

At a recent tractor show I attempted to light the furnace in my mid-nineties Granby. After it failed to light, A friend and I made several attempts to no avail. The furnace cycled through its phases but didn't light. I'm not sure the igniter was working. Hope it's something simple and not a circuit board.
Any advice and help appreciated.

 

[muttmaster]

My Grandby had issue with Attwood furnace too. Try lighting the stivev and let it burn for 30 seconds to purge trapped air. Make sure you have plenty of propane in the cylinder. I also found out that when the hot water heater is on, the furnace won’t light either. Click the thermostat on and off may do the tick too.

 

[ski3pin]

Did you recently open the valve on the propane cylinder? Opening it quickly can cause a misreading in the safety valve and shut down propane supply.

 

[Old Crow]

Please tell us more, spudder....

What model furnace? (so I can look for a manual)

Has it fired up successfully recently?

If so, can you think of anything that has changed since then? (example- propane refill, batteries went low, etc)

Has the furnace been troublesome in the past?

Can you light your stove? If so, does it seem to be working like you'd expect it to?

Did you happen to have oil come out of your propane line when you've unscrewed it from the tank? (to refill or whatever)

Do you believe you have 11.5 volts or more at the furnace?

When you say 'cycled through it's phases', I assume that means the fan ran for bit and then you heard the distinctive click of the attempt to light. But it never fired. Is that correct? Or did it fire and run for a few seconds and shut down?

Did the furnace attempt to light three times, then run the fan for a while, then shut down?

Have you checked wiring connections on the furnace to be sure there are no obvious problems with them? (like the high-tension wire falling off)

Is the control board stable in its carrier and the carrier securely in place?

Have the control board contacts been cleaned (fairly) recently?

Also- my 8516-IV model has this sticker on the motor cover...

(Click to enlarge)



The flashes refer to an LED on the control board (assuming it's the original board). From your description, I'm guessing you'd be seeing the three-flashes one, i.e., the lockout. Yes?


.

 

[kmcintyre]

I had a similar issue w/ my older Eage. It could be any number of things. I replaced a lot of things while I was working on mine (sail switch, jets, etc., etc.) and in the end, it was a circuit board. There's an aftermarket maker of the boards (can't remember the name) but they are cheaper, better built and are a direct replacement. Not terribly expensive.

 

[craig333]

Dinosaur electronics. http://www.dinosaurelectronics.com/Ignitor_boards.htm

I was going to do all of that to mine today. It fires up at home but not in the mountains. Hard to diagnose when it sorta works but the parts aren't really expensive. Instead I wound up cleaning up the shed and around the house. Maybe I'll get to it this weekend.

For those who have pulled the heater out to work on it, how hard is it to disconnect the propane line?

 

[N'kwala]

Mr. Ski, please, you may have explained a recent mysterious event--my furnace was refusing to light, I tried everything I could figure, took it to ATC. Jeff opened the propane, I switched on the furnace and -- hey presto! Furnace lit. Only thing different I can think of is that Jeff turned on the propane, and maybe I'd turned it on too quickly...?...

When you write that there may be a "misreading in the safety valve," is that valve just for the furnace? Because my stove worked ok.

 

[kmcintyre]

Dinosaur electronics. http://www.dinosaurelectronics.com/Ignitor_boards.htm

I was going to do all of that to mine today. It fires up at home but not in the mountains. Hard to diagnose when it sorta works but the parts aren't really expensive. Instead I wound up cleaning up the shed and around the house. Maybe I'll get to it this weekend.

For those who have pulled the heater out to work on it, how hard is it to disconnect the propane line?

That's the board I used... thanks!

 

[ski3pin]

Did you recently open the valve on the propane cylinder? Opening it quickly can cause a misreading in the safety valve and shut down propane supply.

N'kwala, if you open your tank valve too quickly it can send a blast of propane to the regulator - the main regulator in the line from tour tank to all propane appliances - and cause it to restrict flow of propane. Many times this shut down is evidenced by poor cooktop flame, but not always.

If it happens again, a way to check is to turn off all appliances, close the valve on the tank, unhook the tank from the system - as if you were removing the tank for filling - wait just a bit and reconnect everything. Slowly turn on the tank valve and check if the furnace lights. Hope this was your only problem.

Others, if I'm incorrect with the above, please correct my efforts to make this easier to understand.

Mr. Ski, please, you may have explained a recent mysterious event--my furnace was refusing to light, I tried everything I could figure, took it to ATC. Jeff opened the propane, I switched on the furnace and -- hey presto! Furnace lit. Only thing different I can think of is that Jeff turned on the propane, and maybe I'd turned it on too quickly...?...

When you write that there may be a "misreading in the safety valve," is that valve just for the furnace? Because my stove worked ok.

 

[CougarCouple]

Ski I think there was something about opening the other end of the line like the stove. I will check when I get home.

Russ

 

[Old Crow]

On the subject of propane flow restriction.....

I just found this 'Not Your Father's Pigtail!' article which explains where the flow-limiting device is and how it works. It's a bit of a slog to read through but I thought it may be interesting to anyone looking for more detail.

I believe the flow-limiting device is also called an 'excess-flow valve' in some contexts. We see the words 'excess flow' associated with the Quick Closing Coupling (QCC) adapters in this LPG equipment-supplier catalog.

And here's even more reading for those interested in the details of propane tank valves and connectors.. ACME or POL valve required for RV propane cylinders and cylinder recertification. I include this info as some of us (like me!) still have a left-hand-thread POL connector on our regulator pigtail line (the one from the regulator to the tank) and this article provides background on the transition from POL to ACME.

.

 

[N'kwala]

I'll find time to read the material that Old Crow has passed along. It sounds like stuff I should know about.

I think Mr. Ski may have provided me with the answer to my problem. I went out this morning, turned on the propane V-E-R-Y S-l-o-w-l-y, switched on the furnace and --fwoomp! off it went.

I number this among the many Things I should Have Known About, But Didn't.

 

[camelracer]

Ski you're generally correct but I think the safety shutdown device is in the tank connector not the regulator.