Furnace Problems in 2008 Rockwood

[BuckeyeByBirth]

Decided not to go with a digital replacement thermostat since wiring is different and I'm not the world's best when it comes to that stuff. Anyway, got a replacemnt analog thermostat, same brand, same wiring. Changed it out and now the furnace comes on, no hot/warm air and shuts down in about 6 min. Same problem as before except I'm no longer getting hot/warm air during the time it runs for about 6 min. Any thoughts or suggestions??

[Dave_Monica]

Now it sounds like its not lighting...does the stove light? If your propane bottles have been shut off, open them very, very slowly and see if the furnace will light then.

Dave

[BuckeyeByBirth]

Propane has always been on (I hadn't turned it off). I don't believe I even hear the clicking sound for it to light now whereas before it did.

[rracer5]

Originally Posted by BuckeyeByBirth

I'm leaning toward replacing my thermostat. Are there digital models out there that will easily replace my analog stat? If so (or not) where's the best place to look for a replacement stat, either digital or analog, Lowe's, Home Depot, other??

Research this in detail. I don't think all furnaces are compatable with digital thermos unless you also do a circuit board upgrade on the heater to be compatable with the digital thermo. And the wiring is also more involved.

[rracer5]

Originally Posted by BuckeyeByBirth

Propane has always been on (I hadn't turned it off). I don't believe I even hear the clicking sound for it to light now whereas before it did.

Recheck your wire connections to the thermostat. Sounds like you got the blower wires hooked up but maybe the burner control wires fell off?

[BuckeyeByBirth]

Would the burner control wire you're speaking of be the one for "furnace?" These wires (not very big) are very touchy when feeding them into the "hole" on the thermo to then tighten them down. I'll check that wire but wanted to doublecheck back with you to make sure I'm concentrating on the correct wire. All other functions seem to be working, i.e., fan, fan hi/lo, and cool.

Thanks fro your input!

[rracer5]

Originally Posted by BuckeyeByBirth

Would the burner control wire you're speaking of be the one for "furnace?" These wires (not very big) are very touchy when feeding them into the "hole" on the thermo to then tighten them down. I'll check that wire but wanted to doublecheck back with you to make sure I'm concentrating on the correct wire. All other functions seem to be working, i.e., fan, fan hi/lo, and cool.

Thanks fro your input!

Sound like a possibility. That wire may have a contact problem or fell off completely when you remounted to the wall. Good Luck!

[Mountainmanbob]

Burner ignites - goes out after a few seconds


Possible causes:

• low gas pressure
• intake or exhaust vents obstructed
• dirty burner
• electrode(s) out of adjustment, dirty, or defective
• bad control board

Definitions:
sail switch - micro switch with an arm that extends into the blower air stream which closes when the blower reaches approximately 75% of its rated speed. Also called an air prover switch.
limit switch - safety switch, a normally closed switch that opens if it gets to hot, opening turns off power to the gas valve and ignitor board
fan switch - a normally open switch that closes at a preset temperature, causes the furnace to run for a short time after the thermostat opens, allowing the furnace to cool down. time delay relay - same function as fan switch, only has its own heater, also used instead of a thermostat relay in newer models.
ignitor electrode - similar to a spark plug, 2 versions, 3 probe (remote sense) or 2 probe (local sense.)
ignition control board - when powered, initiates gas valve opening and spark sequence which lasts approximately 7 seconds. Older models are 1 try, thermostat must be cycled off for at least 10 seconds before another ignition cycle is attempted. Newer boards are 3 try, will attempt to ignite 3 times at approximately 60 second intervals.
Some furnaces now come with a fan control ignition board. Fan control boards will shut the blower down if ignition does not occur after 3 attempts. Some models will shut down the blower and wait an hour and recycle, if ignition does not occur the furnace is then shut down. Older DSI furnaces, with some exceptions can be upgraded to fan control. See Fan 50 Plus.
gas pressure - LP gas pressure must be 11" of water column (6.25 oz per sq. in.), checking and adjusting requires a manometer.

Marksrv.com rv furnace troubleshooting