help! furnace won't ignite w/ battery=3 a.m. blues

[johnsoba]

We hadn't been cold weather (well, 27 degrees last night) camping in the '82 scamp we picked up this summer, so before a trip this weekend I checked things out and found that the furnace (original Suburban) would not ignite usintg the battery alone, but would when plugged into an outlet. So I replaced the battery (which did show bad) and it fired right up with the new battery.

We confidently letf for our chilly spot by the Greenbrier river in West Virginia, and slept in beautiful warmth for 5 hours. I woke up when I noticed that the blower ran continuously because the furnace wasn't igniting. Luckily we had packed two extra comforters just in case and the weekend was good.

Has anyone had this problem? Is it the furnace? (I'm not sure how it's been maintained.)How long (once I fix this immediate problem) can I expect the furnance to run before I have to charge the battery back up?

This is our first problem. We love the trailer and it's getting so it doesn't seem like a weekend if we're not using it.

Thanks in advance!
Bruce Johnson

[Roger H]

Bruce, I'm going to ask a foolish question here... did you run out of propane? If both tanks aren't on, and you have an auto-switch regulator, it's possible to run out in one tank, have the other full, but there won't be propane flowing to the appliances. If both tanks were "on", then it's possible that your auto-switch regulator may be defective. If it's not auto-switch, then it may be necessary to physically move the lever to draw from the second tank.

Generally, unless there's something physically wrong with the ignitor, if the fan runs, the only other thing to look at is gas flow.

Roger

[johnsoba]

No. It's a good question but it was a brand new canister and the furnace works fine now that I've plugged it in to an outlet at home.

But thanks,
Bruce

[John Campbell]

Bruce,

I had a similar situation while out in our first below freezing outing this fall. My Sububan furnace will not light if I have 3 of the interior DC lights burning. If I turn two of them off, the furnace lights fine. At night, with no lights on, there is no problem. My battery, a deep cycle marine unit, is several years old, but started the trip with 12.8V.

I've been meaning to get out and do some more testing, but just haven't yet. It does appear though that the ignitor on the furnace is sensitive to the voltage it receives. John

[johnsoba]

Thanks, John. Since I just bought this deep cycle marine battery, I didn't bother to test its output. I'll do that tonight.

May I ask how many days the furnace will work without any outside electricity?

Thanks,
Bruce

[Dan Meyer]

The furnace in your trailer has what is known as a sail switch. If the sail switch does not detect enough air flow, your furnace will not open the gas valve, and it will not light.

I would check all electrical connections between the furnace and the battery, making darn sure that all of them are in perfect condition. If any are in poor condition, there will not be enough power at your furnace to operate the blower at full speed.

-- Dan Meyer

[John Campbell]

Dan, This is all making sense now. With each additional light turned on, the fan definitely slows down. When 3 lights burn, I must be dropping below that minimum flow that the sail switch needs to recognize. Turning off the light accelerates the fan and then it must be generating enough flow. Thanks for the insight. John

[Steve L.]

My Suburban heater (which I never use and would never order again) reports that it uses 3 amps per hour. This weekend I was camping and it was low to mid twenties and my electric heater ran all the time. I'm guessing the Suburban would too.

I expect you bought a group 24 deep cycle. That would be about 80 amp hour capacity, and you used about 15 of them in that 5 hours of toasty sleep. Could be that the voltage just slipped down too low to light the furnace.

The fact that the heater fired right up when plugged in and recharging the battery, seems to support that.

How long will the battery run the heater? I think you just found out!

[Brian B-P]

Yes, I had exactly this problem: the Suburban furnace would run the fan but not light on battery power, and worked fine on converter power. The RV shop doing my inspection claimed that this was a symptom of a weak battery, and the battery was indeed dead in one cell. I replaced the battery and have not had this particular problem.

Dan's explanation sounds reasonable to me.

[John Campbell]

Thanks Steve for the information on the draw made by the Suburban. I was just looking through my old documents last night to see if I could find that information. The willingness of members to share ideas about how they use their trailers is tremendous. Your answer also points out the wide range of uses we have for our trailers.

The Suburban is one of the nicest features in my trailer and I would not want to be without it. It has extended our use of the mountains significantly. We are never in a place where electricity is available (except in my driveway) and we do not have a generator. The electric heater option that many use would not help us. Temperatures have been dropping into freezing each night for some time now (often even in mid-summer) and some family members (unnamed here) would not enjoy those cold nights in an unheated trailer. The Suburban is usually turned way down at night because we do have good insulation over us. We often just zip up a couple of thousand feet in elevation for a single overnight on the weekends and the drain on the battery to power our furnace is within its capacity.

What we don't use (and lots of others can't do without) is our AC. We again don't have the electricity to power it and our cool mountain evenings allow the ceiling vent fan to provide all the cooling we need. I'm sure a trip to the southwest would make me happy I have the AC along.

John

[Brian B-P]

Since we're talking about furnace power draw again...
In the recent topic Heating my Trailer! (Minit), there was a discussion of power draw. I supplied what I knew in my post, midway through.

[Gerry]

Has anyone had this problem? Is it the furnace? (I'm not sure how it's been maintained.)

Bruce Johnson
[/quote]

HI Bruce, I had the same problem when I was first checking out things on my 13ft Boler. I had purchased a brand new battery and hooked it up and everything worded fine exept the furnace. As you said the fan would start but it would not ignite.
After a call to the RV dealer who sold me what I thought was a junk battery he informed me I would need to charge it for 2 days to get it up to at least 80% to run my type of furnace to actuate the gas valve while the blower fan was running.
I did this and it all worked fine.
I did run the furnace for a while on AC power and noticed too that the blower fan would run better and faster each time it came on so no telling how much this effected it too.
I spayed some PB Blaster down inside the shaft to the only bearing I could see and this also helped but a word of warning if your furnace is like mine and the fan is inside the triangle heat box. start the furnace while your still working on it to burn off all residue of the sprayed oil as it makes for an embarassing moment in the middle of the night with the smoke alarm going off in the middle of a campground and smoke pouring out of the open windows with the wife hidding her face, holding her breathe, under the covers and you explaining to other campers as to what you did.
Now after our first season of camping and useing the furnace at least once every time it starts up every time.
Gerry

[Roger H]

My Suburban heater (which I never use and would never order again) reports that it uses 3 amps per hour. This weekend I was camping and it was low to mid twenties and my electric heater ran all the time. I'm guessing the Suburban would too.

This is an excellent thread. I had no idea that there were "sail switches" or that they live in furnaces!

Steve, can you expand on this a little? What don't you like about your Suburban, and what would you do differently next time?

Roger

[Steve L.]

My newbie opinion when buying the trailer was that it would provide heat for when boondocking. However, I know now that the amp draw would quickly draw down the battery. Further, it's too darn loud. I'd prefer the cabinet space instead but not enough to deal with the holes after removing it.

When roughing it in cool weather I use a warm sleeping bag at night and the Mr. Buddy heater during the day. If I planned extended cold weather stays, say a week at a time, I'd go the Olympus catalytic heater.

My cold weather camping is pretty much always with shore power. I consider the Polanis electric heater to be one of my better camping purchases. And my two low current (100watt) floor mats are the cat's pajamas. Wretched excess for ol' Castle Pretentious.