# Furnace - Blower Starts, But Won't Ignite



## luv2camp

We needed our furnace (Model - Suburban SF 30F) a couple weeks ago and







wouldn't you know it - it wouldn't ignite.









The blower starts, the ignitor clicks but doesn't light. It tried three times before going into lockout and then needed to be reset at the ceiling unit. I made sure the gas lines were purged - by lighting the stove for a couple minutes. We had one empty propane tank and one full tank. The battery shows a full charge. We tried the furnace several times with no luck. At that point, we decided that we need to pull the unit out of the camper to make sure it's clean and to start testing things.

After pulling the unit out of the camper, we made sure everything was clean. We tested the sail and limit switches. The ignitor would spark. We did all this without gas since we didn't have a hose (and regulator) to connect a propane tank outside of the camper. Being a seasonal camper has it's disadvantages - one being all our tools and such are home. Anyway, we brought the furnace home with us to bench test using our propane line and tank from our grill.

Wouldn't you know, it fired up the first time!







We never tested the furnace in the camper with the thermostat jumped out. If it's the thermostat at fault, why would the furnace blower even start? I believe my husband changed the batteries in the remote, but didn't hit the reset button on the remote this summer. To be honest, I didn't even read about this until I got home last night.







The AC has worked fine, but maybe that lack of a reset affected the furnace only? I'm also wondering if we just have more gas pressure from our grill tank and pressure regulator.

Unfortunately, we can't get back to the camper for a few weeks to test things, but I would LOVE to hear some of your thoughts.

The first thing I plan on trying is hooking everything back up and resetting the remote. If that doesn't work, I plan on jumping out the thermostat. If it's the thermostat, can we replace that in the ceiling unit? If the unit still doesn't kick on with the thermostat jumped out, I've got to believe it's an issue with our propane system on the camper and not with the gas pressure switch in the furnace (since the furnace fired up at home with our propane tank). There isn't much to the propane system in our camper, if I'm correct - the tanks, the switch between the two tanks, the regulator and then the gas lines.

Are we heading in the right direction? Is there something else we should be looking at?









In the meantime, thank goodness for those little ceramic heaters. I knew there was a reason we kept one in the camper!


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## russk42

It's not your thermostat--as you guessed, the furnace won't do anything (including blow or spark) unless the thermostat triggers. The thermostat only does one thing for your furnace---tells it to turn on. the furnace control board does the rest (blower, spark, gas)

I'm inclined to think the problem is in the gas system--i.e. not enough gas getting to the burner


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## OutbackPM

It sounds like you were not getting gas to the furnace because it worked at home and the blower turns on when you turn the heat on.

To be sure it is not the thermostate opperate the furnace in the emergancy mode using the button on the ceiling unit.(72 deg set temp)

Make sure you had plenty of gas in at least one tank. You said you did but I wonder because a low pressure will not light in the furnace but can at the stove thus be misleading.

Good luck and stay warm.


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## mobile_cottager

I was just about to start this topic.....







my furnace will not ingite either. If I place my hand over the exhaust vent, it will then light, someone mention that maybe spiders or something may be causing a blockage?? Currently I have to do this everytime I wnat to start my furnace. This is a major pain.







Anyone ever have this problem and fix for it ?? Thanks.


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## CamperAndy

mobile_cottager said:


> I was just about to start this topic.....
> 
> 
> 
> 
> 
> 
> 
> my furnace will not ingite either. If I place my hand over the exhaust vent, it will then light, someone mention that maybe spiders or something may be causing a blockage?? Currently I have to do this everytime I wnat to start my furnace. This is a major pain.
> 
> 
> 
> 
> 
> 
> 
> Anyone ever have this problem and fix for it ?? Thanks.


I can't imagine how that would help other then richen up the mixture. If that is the case then you must have low gas pressure. This would be my diagnosis for the OP also. You should have 11"/H2O pressure.


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## H2oSprayer

I had a similar problem to this a few years back. Although I had enough gas in the LP tank to run the frig and keep the tanks from automatically changing over, there was not enough pressure to run the furnace. You could hear it trying to light, but it just refused to do so. In my freezing attempts at troubleshooting, I manually changed over the tanks (turned the little black selector valve) and it off we were to toasty toes. Give it a try, hopefully its something as simple for you as well.


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## BoaterDan

Had the same problem fixed by the dealer under warranty. I don't remember exactly, but they said something about some dohicky being out of position so the whatchamacallit wasn't sensing the flame, or something like that anyway. Anyway, the point is try all the simple suggestions first, but in the end it may simply need repair.

I try my furnace a couple times during the summer now.


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## marks

I too, could not get the furnace to start while everything else on gas worked, sort of. I found it to be the regulator at the gas tanks. As my tanks are inline with the OB, one in front the the other, I found that the back tank supplies less pressure then the front tank. I had gas in both tanks but when the switch is flipped toward the back, I can see less gas pressure at the stove and the furnace will not light. If the switch is flipped to the front, stove and furnace work fine. Another clue is the tank level indicator shows empty on the back tank even though it's full.

My temporary workaround is to use only the front tank and switch the back tank to the front when empty. As I haven't even used a tank up yet, it's no big problem. I will probably get a new regulator one of these days.


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## luv2rv

It could also be your battery. My parents were having a similar issue with their fifth wheel. Even though they were on shore power the battery was bad so wasn't getting enough power to the furnace. Blowers would start but furnace would not ignite.

As soon as the battery was replaced with a new one ... end of problem.

Wayne


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## mobile_cottager

Well I talk to my dealer, not much help.







I had to remove the furnace and found the regulator for the propane was partialy blocked with a small piece of gasket material.







. All good, now I wll have toasty buns all weekend


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## Oregon_Camper

mobile_cottager said:


> Well I talk to my dealer, not much help.
> 
> 
> 
> 
> 
> 
> 
> I had to remove the furnace and found the regulator for the propane was partialy blocked with a small piece of gasket material.
> 
> 
> 
> 
> 
> 
> 
> . All good, now I wll have toasty buns all weekend


Hopefully that was under warranty.

Either way...glad it is now working for you.


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## Sweathog62

We'll it seems i have joined an elite group of people who's furnace will not fire. The following is my situation:

This morning I blew the fuse because I had 2 ceramic heaters on low while lighting the furnace. In my attempts to restart the furnace, it will not light. The fan comes on but no flame and then it shuts off. Currently attempting to purge the lines via pg 4 of the suburban gas furnace guidelines.

Any other ideas??

BTW: Unit worked fine for 30 minutes prior to the start of the trip.


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## CamperAndy

bradhelton said:


> We'll it seems i have joined an elite group of people who's furnace will not fire. The following is my situation:
> 
> This morning I blew the fuse because I had 2 ceramic heaters on low while lighting the furnace. In my attempts to restart the furnace, it will not light. The fan comes on but no flame and then it shuts off. Currently attempting to purge the lines via pg 4 of the suburban gas furnace guidelines.
> 
> Any other ideas??
> 
> BTW: Unit worked fine for 30 minutes prior to the start of the trip.


Sounds like low propane level but I have to ask what fuse blew as using AC powered ceramic heaters have no impact on the 12 vdc system that the furnace uses.


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## Lmbevard

luv2camp said:


> After pulling the unit out of the camper, we made sure everything was clean. We tested the sail and limit switches. The ignitor would spark. We did all this without gas since we didn't have a hose (and regulator) to connect a propane tank outside of the camper. Being a seasonal camper has it's disadvantages - one being all our tools and such are home. Anyway, we brought the furnace home with us to bench test using our propane line and tank from our grill.
> 
> Wouldn't you know, it fired up the first time!
> 
> 
> 
> 
> 
> 
> 
> We never tested the furnace in the camper with the thermostat jumped out. If it's the thermostat at fault, why would the furnace blower even start? I believe my husband changed the batteries in the remote, but didn't hit the reset button on the remote this summer. To be honest, I didn't even read about this until I got home last night.
> 
> 
> 
> 
> 
> 
> 
> The AC has worked fine, but maybe that lack of a reset affected the furnace only? I'm also wondering if we just have more gas pressure from our grill tank and pressure regulator.


One of the reasons that the furnace would light with the propane setup from the grill is that it is a high pressure system whereas the OB has a low pressure system. This is why you have to buy a special grill to hook up to the gas system on the OB or a separate gas regulator system to attach to one of the tanks. I would think that the problem had to be low gas pressure as everyone else was saying. Another problem with turning the gas on and off in the OB is that the tanks Overflow valve sometimes sticks close or part way closed, enough to get a flame on the stove but not enough to provide the higher flow to the furnace. Good luck everyone and stay warm.

BTW 1200 W + 1200 W = 23 amps running two heaters, starting up anything would pull over 30 amps.


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## Sweathog62

Point taken.. I did not blow a fuse, I tripped the circuit. Easy fix, as I just toggled it back and forth and re set it... The problem remains that I could not re light the heater.

Just shut everything in the TT off for about 5 minutes to try and see if it would re set the heater....


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## Sweathog62

bradhelton said:


> Point taken.. I did not blow a fuse, I tripped the circuit. Easy fix, as I just toggled it back and forth and re set it... The problem remains that I could not re light the heater.
> 
> Just shut everything in the TT off for about 5 minutes to try and see if it would re set the heater....


Good news.. When you trip a breaker while the heater is running you have to shut down all the power from your 12 volt batter in order to reset the emergency shut off valve on heater.. Yes, the click was heard and within about 20 seconds it is know blowing hot air...

Thanks for everyone who responded.. Yes, I've read these before and never thought it would happen to me...


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## Brian Meyer

mobile_cottager said:


> I was just about to start this topic.....
> 
> 
> 
> 
> 
> 
> 
> my furnace will not ingite either. If I place my hand over the exhaust vent, it will then light, someone mention that maybe spiders or something may be causing a blockage?? Currently I have to do this everytime I wnat to start my furnace. This is a major pain.
> 
> 
> 
> 
> 
> 
> 
> Anyone ever have this problem and fix for it ?? Thanks.


I had the same problem so I put my hand over the exhaust vent and I felt the furnace fire and vent heat out of the exhaust vent. I also had an empty tank on the side of the trailer as the regulator so I switched the full tank (from the opposite side to the regulator side) and after a couple of tries, it worked like a charm.


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