Furnace problems.

marchesi · 11-21-2008, 09:59 AM

Hi everyone,
I just purchased this summer a 2005 Ford 4x4 sportsmobile. As fall came and I started camping in the cold the furnace doesn't seem to hit up the van more than 55-60 degrees with temperatures outside not even that cold (40s). The furnace runs nonstop even at night when I put the thermostat down to 50. I have the standard 12,000 BTU suburban furnace and sportsmobile swears that the furnace is more than sufficient to heat up the van even with the top up. The RV shop here in Montana tells me that 12,000 BTU is not sufficient to heat up the van and wants to sell me a bigger furnace. I think they just don't know how to fix my furnace... What do you guys think? Have you camped in cold weather and tried to heat up the van with the top up? Or even down?
Thanks!
Paolo

Scalf77 · 11-21-2008, 10:17 AM

Paolo,

In my experience that furnace has no problem heating up a SMB with the top up. It is notoriously a cranky device, need to make sure that you don't have any air in your propane system, you need to have high enough voltage to make sure the fan blows enough to close the sail switch. read http://sportsmobileforum.com/viewtopic. ... ht=furnace for some help on this furnace, Do you actually feel any hot air coming out, it will try to fire it three times and then lock itself out and that I believe leaves the fan blowing as a safety precaution. The manuals for the furnace can be found http://sportsmobileforum.com/viewtopic.php?t=186.

Hope this helps, or at least gets you going in the right direction.

Greg

marchesi · 11-21-2008, 10:25 AM

Thanks for the info Greg. The furnace blows hot to luke warm air but mostly luke warm air. I turned on the gas stove to see if there was any air but it doesn't seem to be the problem, it's burning nice and hot. I also connected the van to shore power to make sure the battery wasn't an issue. Hummmm...

Greggd · 11-21-2008, 11:34 AM

marchesi ,
#1 check to make sure that your thermocouple is functioning .
#2 Make sure that your Gas Jet is not clogged with miniscule Cob/Spider Webs , try blowing out the inside of the unit periodically
as fine Talc type dust can clog your gas orifice as well a the Cob Webs As far as the BTU's you have more than enough .
Greggde

Greggd · 11-21-2008, 06:03 PM

marchesi ,
Is your FLAME NICE AND BLUE in color and have you looked at the PILOT ? if the PILOT OR VENT appears to be SOOTY then you are not achieving proper combustion and these Force Air Furnaces have three safety devices that prevent accidents .
#1 Thermocouple #2 Sail Switch/Air Prover #3 Limit Switch these are in line to achieve the proper operation and combustion of this furnace
you mentioned that you had turned your stove on to purge the Gas Line's,sometimes you have to leave your stove on for up to 10 minutes to clear the line's , you should check your FRESH AIR INTAKE
for obstructions . If these procedures don't allow for proper operation then I would check the PROPANE FUEL LINE AS YOU NEED 11 INCHES WATER COLUMN , this will require the use of a MANOMETER that every RV repair shop worth their salt will have . And contrary to common belief these are very simple hard working units that with the proper scheduled preventative maintenance will serve you well . We have had numerous vehicles that came with the Suburban Furnaces and after I learned about the maintenance schedules never had any problems .
Greggde

oclv · 11-21-2008, 09:07 PM

Posted: Sat Nov 22, 2008 12:04 am Post subject: Furnace problems

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marchesi ,
Is your FLAME NICE AND BLUE in color and have you looked at the PILOT ?

I have the Standard Suburban propane furnace that was used in 2004. We bought it used this spring. Right before we left for a trip I was trying to familiarize myself with everything and coudn't find the pilot light. I called Sportsmobile and was told that it does not have a pilot. It has a fancy word but I think basically he was trying to say that it was some kind of electronic igniter. We experienced a problem this fall when in the cold at elevation. Our problem was due to a weak battery and did not show the symtoms that yours is showing. To respond to the comment from your service place I can say that our furnace heats the van fine. In fact we normally turn the thermostat up to 80 or whatever is the highest setting and let it run until the van is real warm. Then we turn it off until we wake up and do the same thing. It makes quite a bit of noice and is under our bed so we don't run it at night (down comforter). Keep us posted as to what you find. oclv

Greggd · 11-22-2008, 07:09 AM

Their are three types of ignition system's employed for the Suburban
and Attwood RV Furnace's
#1 The Standing Pilot . Lit with a Match .
#2 The Piezoelectric Start ignition , for lighting a Standing Pilot .
#3 The fully Electric Start ignition system that has it's own transformer that provides the source of ignition , all three are still employed in the industry today with #3 being the most frequently used .
Greggde

marchesi · 11-23-2008, 06:56 PM

Thanks for all the good info! I took all your replies to the RV service place that is working on the furnace. Unfortunately they charge $100 an hour for their work but they are worth a $1. Hopefully with your comments they'll be able to figure the problem out...