Surburban Sf-30f furnace

[Degman]

We have a 2006 Sprinter, Copper Canyon fifth wheel and owned it since new. Furnace has worked well until the start of last fall. Prior to the trip I always test everything before going and ran furnace for about 1-2 hours of time and ran fine. Arrived at campground aound lunch and at dinner time turned on heat and furnace would not come on. blower yes, ignitor yes,heat no. 3 times then lockout, tried again and put hand over intake and furnace actually turned on, ran through cycle and upon start of next heating it would not start again, smell gas out of exhaust so i know its getting gas. used second heat source for that weekend. came home and cleaned furnace and it ran fine. Just went on first trip of 2013 and same problem occured with furnce, worked when temperature was 50 to 60 outside but doesn't work when temperature drops below 45 degrees. I have spent hours reading posts and researching and think the control board is the issue. looking for help

[Ronandpat]

Could possibly be the sail switch. If the furnace thinks the blower is not running it shuts off.

[rreynold51]

Could be a regulator issue...some times they allow gas to flow but restrict it such that the furance won't work...had an issue with mine very similar...but when I switched to my other propane tank it worked!! Some problem internal to the regulator.....my stove worked fine....regardless....and so did the hot water heater...only the furance didn't like it!!

[Old-Biscuit]

When the control board gets power (after fan runs, sails witch makes up, thru high limit switch) power is then applied to gas valve AND spark electrode.

Gas flows and is suppose to be ignited by spark electrode.....then when flame is established the spark electrode is used as flame proof.

If you smell gas......valve is opening BUT is not igniting either because of no spark OR electrode is not properly positioned
1/8" gap between electrode and ground rod plus electrode needs to be in flame path

You might also need to clean furnace/burner again......mud daubers/spiders/debris can really mess up the combustion air flow

[enblethen]

Is it getting propane? May take sometime to purge air from lines if you changed out tanks.
Do you hear the ignitor clicking?