Foretravel Owners' Forum

Foretravel Motorhome Forums => Foretravel Tech Talk => Topic started by: kb0zke on October 17, 2018, 09:55:52 pm

Title: Front furnace
Post by: kb0zke on October 17, 2018, 09:55:52 pm
It got cold enough the other day that I thought I'd try the propane furnaces BEFORE I needed them. The back one worked just fine, but the front one just sits there, taking up space. I can get a click out of the thermostat, indicating that it is calling for heat, but that's it. No fan, nothing. First thing I did was check the fuse. It turns out that the front furnace and the fixed table light are on one circuit and the light was on, so that says the fuse is good. Just to be sure I pulled the fuse and Jo Ann started hollering that her light just went out.

Tomorrow is supposed to be a pretty nice day so I'll get out the meter and start checking things. Suggestions are welcome. I thought about checking to see of the fan actually turns, and then realized that if it didn't the fuse would blow. Fortunately the electric heat works just fine.
Title: Re: Front furnace
Post by: bdale on October 17, 2018, 10:07:25 pm
Do you have a bay door that opens in front of the furnace exhaust?. If so, could be the switch that prevents it from running while the door is open.
Title: Re: Front furnace
Post by: OffTheGridRVs on October 17, 2018, 11:08:38 pm
My previous rig (SOB) did the same thing after summer was over, turned out to be mud daubers all over the squirrel cage fan keeping it from spinning.
Title: Re: Front furnace
Post by: Chuck & Jeannie on October 17, 2018, 11:10:57 pm
David,

Link below to Atwood service manual - most likely covers the model in your coach.  Contains a trouble shooting section.

Also, you can Google "Atwood Hydro Flame trouble shooting" and find some helpful videos on YouTube.

http://bryantrv.com/docs2/docs/hflamefurn04.pdf
Title: Re: Front furnace
Post by: Neal Pillsbury on October 17, 2018, 11:38:12 pm
David,

The prior responses contain good technical advice.
First, though, when these furnaces have been inactive for quite some time (a few weeks to months),  my experience has been that oxidation of wiring connections/switch contacts is a likely source of a "non-start" problem, i.e. - when you only get a thermostat "click".  A  bit of "wiggling" of contacts and preventive maintenance in the form of dielectric grease often helps:
See Randy's recent thread:

Furnace no go (http://www.foreforums.com/index.php?topic=34891.msg323493#msg323493)

HTH,
Neal

P.S. - If this turns out to be your solution, it may just start another "Bottle Rocket" thread.  😃
Title: Re: Front furnace
Post by: Mike Leary (RIP) on October 18, 2018, 09:21:17 am
My fairly new Atwood was doing that after we drove through a sandstorm and hurricane winds/rain coming down from the high country to Ajo. It had a fresh Dina board, so I was perplexed. I noticed a lot of dust in the compartment, so I got my compressor out and aired-out everything, including when it was running. Working fine now. (fingers crossed) .
Title: Re: Front furnace
Post by: kb0zke on October 20, 2018, 03:29:56 pm
Well, I've had a couple of nice days to poke around some. The manual referenced above is very helpful. At this point I'm thinking that either the thermostat is dead or the motor is dead. I'll keep poking. Worst case I'll add it to the list of things FOT will check next month.
Title: Re: Front furnace
Post by: Tim on October 20, 2018, 07:15:51 pm
Make sure the On/Off switch on the furnace frame is switched to "On".
Title: Re: Front furnace
Post by: kb0zke on October 20, 2018, 09:18:28 pm
Tim, that's the part that I'm most concerned about. I suspect that it may not actually be turning on. Since there are only two wires I'm thinking that I may just try jumping across them and see what happens.
Title: Re: Front furnace
Post by: Old phart phred on October 21, 2018, 01:28:27 am
Jumpers are quite valuable in diagnosis, start at the thermostat, voltmeter also quite valuable, eleminate one component at a time until it works, furnace has many safety switches.
Title: Re: Front furnace
Post by: Tim on October 21, 2018, 08:41:13 am
Yes. If it's getting 12 volts, you can jumper the two blue thermostat wires and the furnace should start.
Title: Re: Front furnace
Post by: kb0zke on October 21, 2018, 06:11:39 pm
Was looking for a very short project to do this afternoon between other stuff, so jumped the two wires. Shortly thereafter the furnace came on. It seems that the on-off switch actually just lifts a small piece of springy metal (copper, maybe?) off of a contact point when the furnace is turned off and lets it snap back against the contact when turned on. Apparently the non-use for the past six months or more gave that springy metal a bit of a set so that it didn't make firm contact. It does now.

Temperatures are up around 70, so furnace not needed. Oh well, at least I now know what to poke at if the furnace doesn't behave when we get colder temperatures again.