Airbag's heater/furnace

[JohnEd]

Airbag,

Did I miss the grand finale?   Expiring minds and all that.

From Feb 09

Airbag,

Your furnace looks excellent.  It will be running and heating when we are both gone.  That part about the heat exchanger being the last one is not encouraging.  It is exactly like mine...drat!

You can bench test that puppy out of the coach without problem.  You only have to short the thermo line to ground to get the "heat" needed signal.  The bat voltage must be above 10 volts or something but it draws only 6 or 7 amps so you bat will be OK.  The problem, if there is one, will be the propane pressure.  When you set the thermo it will take a while to start the gas and the igniter.  The igniter is easily heard as a crackling sound.  Gas ignition is a whump and volume is determined by how much over the limit the pressure is.  Initially, mine shook the sink cabnet.  Look into your flame view hole and make sure you have all blue flame.  As the gas orifice is not available in a tournament selection of sizes and the water heater and the other appliances are, I adjusted the flame by adjusting my gas pressure to meet the immediate needs of the furnace and then rejetted everything else.

The cracked exchanger might have had its life shortened by inadequate air flow thru the furnace.  When it is choked off it gets really hot fast and the overtemp shuts off the gas.  It isn't  supposed to be part of the "normal" operation as it is a safety device.  Make certain your furnace duct holes ALL (4) have a hose connected.  The runs should be short and straight.  Right angles in that "clothes dryer" flex duct eat up the airflow.  I installed 90% metal tube duct for the single corner I had.  Where the original design ran one hose to the living room and blocked of the second, I ran both to the same wall and doubled the air to the Living room.

You will really like that furnace.  It is very quiet once you get some weights attached to the large area sheet metal parts.  The only sound you could hear from mine was the gentle whoosh of air from the registers.

Good luck with this, guy.  Let us know.

John