Hydro Flame 8531-11 furnace problems

[BobFunck]

Hi,

My Hydro Flame 8531-11 furnace is not working on my 1994 Thor Chateau that I just bought used. I set the thermostat to heat and the fan motor turns on but blows cold air. I went outside and took off the furnace panel, removed some debris that was in there, but saw no other obvious problems. I didnt hear the ignitor clicking. Gas seems ok as I am getting gas to the stove top with generally good flame on all burners. I dont see any gas shutoff valve for the furnace anywhere, nor have I found any fuses. I am smelling gas around the LP tank and also near the furnace when I first turn on T Stat. Any suggestions? do I need to replace the ignitor?

Bob

[wolfe10]

Yes, the sail switch must close before propane valve is opened or igniter triggered.

Causes of sail switch not closing:

Low voltage-- fan turn too slowly. Try with the engine on or plugged into shore power and see if it works.

Obstruction in air return to furnace (inside coach).

Outlet vents closed, duct crushed, etc (inside coach).

Yes, if this does not solve it, you are in for more involved servicing.

[mchero]

I'd strongly suggest you pull that furnace and give it a good cleaning. Might find issues you won't find if you left the furnace installed.
I found some mice nests in behind the furnace.
Also easier to service when it's on a bench.

Great furnaces, I have two in my 93 Pace Arrow Diesel Pusher. Both still going strong with ORIGINAL igniter boards.

[darsben]

The owners manual troubleshooting guide is here
http://bryantrv.com/docs2/docs/hflamefurn04.pdf

First thought should be the sail switch as you said there was debris in the area.
Sequence for ignition is
1 call for heat
2 blower starts
3 sail switch closes because of air movment
4 ignition circuit check
5 ignition.

So the first thing to do is find the sail switch and check it

[enblethen]

Welcome to RV.net!
You need to clean the furnace compartment good.
Normal problem is the sail switch being dirty. If the sail switch does not operate, no power gets to the ignitor board.
You can use compressed air to blow compartment out good. If you can see the sail switch, even a can of compressed air for computers may be enough to blow it clean.
Next would be to check for power. The time delay relay closes after a short period of time, 10-15 seconds, the power then goes toward the circuit boar via a high temperature cutout, then sail switch and the the circuit board.