Furnace Issue

geesal · 03-23-2011, 07:23 PM

1999 25FL Ultra Lite, My furnace will light momentarily then go out. I checked the gas line after the valve and just before the valve. I blew out the tube in the chamber. Replace the electrode and the pressure regulator at the tanks. The blower comes on, the igniter clicks and a flame appears briefly. What would be the most reasonable choice left, the board or the valve?

Thanks in advance for any help

The_Stuff · 03-23-2011, 08:04 PM

the tanks. shut off tanks, turn on stove for a min to let the lines de-pressure. turn off stove, turn on tanks SLOWLY and at the same time if you have 2.

sherdep · 03-23-2011, 08:10 PM

Might be silly to ask but I am gonna ask anyways

did you start the stove to get any air in the lines out and does it stays running?

Do you have enough propane in the tank?

MotocrossCamper · 03-23-2011, 09:42 PM

Quote:

Originally Posted by sherdep

Might be silly to ask but I am gonna ask anyways

did you start the stove to get any air in the lines out and does it stays running?

Do you have enough propane in the tank?

We used to have a furnace that was really bad about that. Every time you wanted to use it you would have to light the stove and get the air out.

geesal · 03-24-2011, 06:16 AM

Forgot some info, it is a Suburban NT 20S furnace. Tried the turning on tanks real slow, no change. I installed 1 new tank and the selector is set to that one. I have to make sure the main line is completing install on the new regulator as it was freezing outside when I put it on. Made sure the electrode was about an 1/8 inch from burner. The 2 times I did get the furnace to stay lit (prior to the new electrode and trying to clean out), I did have the stove and oven on. I can see the spark, and sometimes the burner lights, then goes out. My thoughts are: Either the furnace is not sensing the flame (board?), the board is not keeping the valve open, or the valve is not staying open.

Filthy Beast · 03-24-2011, 06:41 AM

My bet would be the board. It sounds as if the flame sensor is not getting a signal. The current of the signal is extremely small. I know it used to be in the 25 microamp range.

**Herk7769** · 03-24-2011, 06:55 AM

I had the same symptoms this year. No matter what I tried the left (driver side) tank on my 5th wheel would not feed gas "enough" to run the furnace.

Turned out my pigtail connector to the tank was bad (there is an internal check valve in the tank connector that can become clogged with oil or just plain break). However my ham fisted troubleshooting with an air compressor destroyed the red "high pressure" regulator on the driver side AND the auto-switching low pressure regulator on the passenger side. Expensive lesson learned.

geesal · 03-24-2011, 07:17 AM

I'll try the pigtail first (least expensive, and they do look old and dry), if that doesn't work, I'll pull the board and and have one of the EE's here at work look at it. Herk, looking at your picture and name, I assume you are C130 person. 7 years on HC's and E's in the AF and reserves.

kenair · 03-24-2011, 11:05 AM

This january, When I picked up my 2006 surveyor 260 at the dealer we did a walktru inspection in the shop, the furnace was acting up similar to what you describe. After pulling out the furnace, 2 hours of fixing he replace a gas flow valve in the furnace. I've tried the furnace twice since then, so far ok.

Good luck on yours. Ken

rracer5 · 03-24-2011, 11:34 AM

Still diagnosing a similar problem on my unit. TT was new and we used the curbside tank first last fall with no problem. I then switched the regulator to the streetside tank, took the empty tank and got it refilled. After I used up the streetside tank (yea, it was late November & we were on site for 2 weeks), I switched back to the curbside tank and experienced very low flame on the stove and the furnace air would only get "luke warm". And, the pigtail from the tank was showing signs of freezing up (white frost on the outside of the hose). I took that same tank and put it on the streetside and it worked flawlessly so, that ruled out moisture IN the tank from the refill. I purchased a new pigtail but, didn't have a chance to check it before putting TT in storage. Will check it out in a few weeks. I have a feeling it's going to be the switching valve because that is the only mechanical thing I touched during this whole process.

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