Question about Attwood heater.

[Casa Escarlata Robles Too]

On our Alaskan trip I had to use the heater a few times. Usually just in the morning.
I would switch the thermostat on ,the fan would start than the gas/flame would cycle on and off but not stay on to provide heat.
After messing with the temp setting it would finally stay on until the temp was reached than shut off like normal.

I could hear the gas igniter click,light the gas than after a few seconds it would shut off only to click and ignite again.

Is this a thermostat problem and I should replace the manual one with a digital one.
Or is there something wrong with the gas/valve/igniter?

After say a few minutes messing with the thermostat the heater would run great and crank out the heat.
Any ideas would be helpful.

Frank

 

[billharr]

Check your sail switch. There is a thread on WTW somewhere.

 

[ski3pin]

I don't think its the thermostat. As Bill says, check the sail switch - sorry I don't have the time to find a thread on that now. Another possibility is the adjustment of the ignitors at the burner.

 

[Bombsight]

Where and what is a sail switch? I ask because when in Colorado this past June, my furnace would run long enough for us to fall asleep ... only to wake up freezing 3-4hours later.

 

[PaulT]

Search for "atwood furnace sail switch" and you should find too much information. Some of it may be useful.

Paul

 

[cwdtmmrs]

The sail switch is simply a micro switch with a sail on it to catch the air from the blower wheel. Its purpose is not to let the gas flow and ignite unless the blower is working. same in a home forced air unit.

The flame in the burner box will cycle on and off with the blower running to try and keep an even temp for the outgoing air. That is normal and has nothing to do with the thermostat. The air outgoing air should stay warm throughout the process and not blow cool or cold air though.

cwd

 

[Casa Escarlata Robles Too]

Thanks. The gas cycling isn't long enough to get warm. But after a few trys the heater works OK.
I haven't checked into it yet ,seems like other things to do.
Thanks for all the info.
I still may go to a digital thermostat.
Frank

 

[Casa Escarlata Robles Too]

Check your sail switch. There is a thread on WTW somewhere.

Thanks Bill. Knew you would have some help.
Frank

 

[wuck]

Here's a short thread on the sail switch. There are many others, type this into your favorite search engine:

"sail switch" site:wanderthewest.com

 

[CougarCouple]

Hello -casa-escarlata-robles
Most if not all furnaces have many safety's to prevent a run away fire. The sail switch is one to prove the blower motor is operational to remove the heat. There should also be a sensor to prove flame. Turn it on stand out side. Listen for blower to start. Look and listen for ignition see which one stops first. How it proves flam would need to look at mfg. specs to see how they do it. Might still be sail switch, would need to jump it out to prove it then figure out how to fix. Never leave a safety jumped out.
Russ

 

[Bigfoot Dave]

I just had a problem with my camper furnace. Turned out that the igniter/flame sensor had a crack in the ceramic where it passed thru the metal bracket that held it. It would sometimes light but then go out. You could hear the sparking but it wasn't in the right place. It would cycle 3 times and shut down. When I replaced it It took a try or two to get the gap right and now it works great. On mine the gap between the igniter and the ground rod needed to be 1/8" and they both had to be 1/4" off the burner surface. Good luck, Bigfoot Dave

 

[Casa Escarlata Robles Too]

Thanks for all the info.
My problem sounds more like Bigfoot Daves.
I'll have a go at it .
Thanks
Frank

 

[Casa Escarlata Robles Too]

I just had a problem with my camper furnace. Turned out that the igniter/flame sensor had a crack in the ceramic where it passed thru the metal bracket that held it. It would sometimes light but then go out. You could hear the sparking but it wasn't in the right place. It would cycle 3 times and shut down. When I replaced it It took a try or two to get the gap right and now it works great. On mine the gap between the igniter and the ground rod needed to be 1/8" and they both had to be 1/4" off the burner surface. Good luck, Bigfoot Dave

Did you replace it yourself? How hard is it?
Thanks for the help.
Frank

 

[Casa Escarlata Robles Too]

Here's a short thread on the sail switch. There are many others, type this into your favorite search engine:

"sail switch" site:wanderthewest.com

Thanks for the info.We did have a lot of dust before we got to cooler temps and the need for the heater.
The thing is it finally stays of after a few trys by the igniter .
All things will be checked.
Frank

 

[Casa Escarlata Robles Too]

I don't think its the thermostat. As Bill says, check the sail switch - sorry I don't have the time to find a thread on that now. Another possibility is the adjustment of the ignitors at the burner.

Thanks Ski check when you have the chance.
Frank

 

[Old Crow]

I'm a little late to this thread but here was my experience with a bad igniter on my furnace. That thread includes some notes on what I ran into in swapping in a new one.

In my case, the central wire in the igniter had somehow broken loose from the insulator and would turn inside it instead of being held steady. The furnace would sometimes fire (after a lot of tries) but wouldn't continue running if it did.

The continue-running issue may be related to the second function of the igniter assembly. We call it an igniter but its both a sparking gap and a flame sensor (Atwood calls it a 'spark-and-sense electrode'). Both functions of the electrode are managed by the logic board. My point is the intermittent nature of it may be related to a problem with the electrode itself but could also be a bad electrical connection, a problem with the logic board itself (perhaps even a cracked lead or cracked board), or other reason.

You might find this furnace troubleshooting guide helpful. If you can find the service manual for your model furnace, that would also provide drawings of components, part numbers, etc.

Good luck!

 

[Casa Escarlata Robles Too]

Thanks Old Crow. Good trouble shooting answers.
Frank

 

[Casa Escarlata Robles Too]

This morning I got to work on the heater.
Took off the inside vents nothing there.
Next removed the outside cover and fount the electronics board had a loose screw and was resting on the fan housing
Tightened the screw and made the board nice and snug than cleaned out any dust that was there.
Switched the thermostat on and set it to highest temp,and after the normal time flame came on and stayed on like normal.
Cooked the camper to a balmy 85* than it shut off.
All seems to be OK.
Will have to wait for some real cold weather than run it again.
Thanks for all the suggestions.
Now back to a new thermostat. What simple one should I get,or just stay with the manual one?
Frank

 

[CougarCouple]

Glad you found it CRET
Sometimes they bond the board to complete a circut. You can see a metal ring around the hole the screw goes thru. Glad it was easy fix for you.
Russ

 

[Casa Escarlata Robles Too]

Looking back on when the problem started,we had just traveled the 134 miles of gravel "Old Denali Hwy."and many miles in the Yukon on very ruff road work roads.
I am going to put a longer screw in, the other is a little stubby one.
Frank