Furnace questions

[Ellie & Carl]

OK.... just over one week of ownership, so PLEASE excuse me if I ask questions that may be old hat. I've been on several other forums for my other passions - motorcycles and diesel trucks - so I know there's a wealth of knowledge waiting to be tapped out there. Airstreams are new to me.... but basics aren't. Thank you in advance!
We bought the thing 8 days ago and the one part missing was the furnace. Craigs list got us a replacement (three years newer than our trailer). I haven't hooked it up, yet, but questions have arisen regarding a "safety check".
We're doing this renovation/repair on somewhat of a tight budget. I'm a pretty well-rounded repair person, having worked for myself as a professional handyman for 9 years, so I'm not afraid to do what has to be done.
I haven't taken any of it apart. What do I need to look for? I hope to clean up the sheet metal housing and throw some fresh paint on that. The motor is free-wheeling. The whole unit is currently sitting inside the door of the trailer. Tips.... suggestions... warnings???

[HowieE]

I think I would fire it up before bothering to install it. That way you will know if it is worth the effort.

This will check the control board, the sail switch, blower motor, gas solenoid, and heat exchanger for exhaust leaks.

When you first hook propane to it crack the flare nut at the unit till you smell gas. If not the pilot orifice will never bleed off to let it ignite with out several cycles and you will think there is a problem when there may not be.

[Skater]

Look through it and make sure the exhaust is clear and all that - it won't start if the sail switch isn't satisfied, which means that it has to detect exhaust flow. One thing is that spiders love propane so I'd try to check/clean the gas line going into it.

I've learned from taking mine apart repeatedly (sigh) that there really isn't much to them; the operational flow is pretty easy to follow, so you should be able to spot any problems pretty easily.

For testing, what Howie said is what I'd do - but I wouldn't even hook propane to it at first and verify it starts and goes through the cycle, including running a minute or so after you shut it off. Then I'd run propane to it and verify there are no leaks (soapy water) and that it produces heat.

[david686]

Hi, "Skater" - when testing a furnace, how will it run through the cycle with out being connecter to a gas source (propane)? Just wondering for future information.

[3 Dog Nite]

Not skater but here goes. The fan will kick on, the air lifts the sail switch, the board will try to ignite the flame. Just listen for the clicking sounds. Make sure the board shuts everything down after numerous attempts to ingnite. My furnace will try 3 tries before shutting down.

It's worth a trip to the hardware store to get the fittings & hose to hook it up to a 20# BBQ tank out at the picnic table. I'd rather see a bad furnace burn the table & not my AS.

Ricky

[Aage]

Ellie & Carl:

Welcome to Airforums.com! I have the same trailer, only a few years newer, and we love it! Lots of room, and not so heavy it can't be towed with something other than a pick-up truck.

As for your furnace, if you do a simple search on "furnace" (look for the "Search" button in the top blue bar, the Google search is the fastest) you will get a zillion posts on this issue.

First of all, they rust as they age (in any climate), and the combustion chamber can wind up with holes. I'm sure you will agree that holes where hot gas is burning is something less than desireable!

So, HowieE's advice is solid: have a good look at it and make sure it runs before putting it in your TT (travel trailer).

Give it a good shake out, and make sure you get all the junk out you can, and especially have a close look for mud daubers' nests (they love gas too, it seems!)

A common defect that they all seem to get with age is that the short tube that connects the blower cage to the combustion chamber will crack and fail. Another "Not A Good Thing" item, a must fix. There is a forum member who has replaced this with part of a rad hose several years ago, with no problems, but your mileage may vary.

At the end of the day, at some point you'll ask yourself if it's worth the savings and more to the point, are you comfortable using a furnace that is well over thirty years old in your TT.

Good luck with the work, and let us know how it all works out.

ps: a worthy investment would be to find a copy of the Service Manual for your trailer. Chock full of illustrations and info. Not sure if they made them as early as '69, but even one a few years older will be very close to your TT in detail.

cheers,
Aage

[Ellie & Carl]

As I alluded to, in my initial message, I knew there'd be a whole lot of knowledge from the members of this forum. Thank you, everyone!
I think I've got a few hours of tinkering to do (including some serious cleaning!). Which made me think of another couple questions:
1) Is there anything (including the sail switch) that I could damage by introducing compressed air as a cleaning aid? If everything seems OK, and I can avoid tearing the whole thing apart, will I damage it with the compressor?
2) What do all you AS gurus think of catalytic heaters? When initially cleaning out the trailer, I came across two (different size/BTU capacity) cat heaters. I'm thinking that if it's not contraindicated, I might hook one or both of those up as alternative heat sources.... which naturally begs another question: are these really safe without venting?

[Aage]

Originally Posted by Ellie & Carl

2) What do all you AS gurus think of catalytic heaters? When initially cleaning out the trailer, I came across two (different size/BTU capacity) cat heaters. I'm thinking that if it's not contraindicated, I might hook one or both of those up as alternative heat sources.... which naturally begs another question: are these really safe without venting?

Catalytic heaters will warm the cabin, but IMHO there is nothing like a fan to drive warmth around fast and get the temperature up quickly.

Another issue is that on your trailer, the furnace also supplies hot air to the space below the floor, directed at your water tanks. I think you can see those ducts under the sink area in your trailer. This is done to prevent freezing, and all the nasty things that could accompany that.

Can't comment myself on safety since I have never used a cat heater, perhaps others will jump in. Personally I can't see how burning LP gas without properly venting the process could be healthy, but what do I know? If I DID use one, for SURE I would crack a window or two open...

[HowieE]

The sail switch is just a micro switch and is sealed so plowing with compressed air should have no effect on it.

The cat heaters if left uncovered for a period of time are most likely contaminated, but lighting is the only way to tell. Mine was left in use and uncovered for 3 seasons and by then the output had decreased to the point I sent it back for a new element, about half the cost of a new one.

Cat heaters heat YOU they do not heat the space. They are almost instant and great to sit in front of. They also do not blow cold air for the first and last Minuit of operation, very distracting if you are sitting watching TV.

Yes I have my 2 roof vent open about 2 in. year round for ventilation.

[Ellie & Carl]

.... I was!
I dug into the furnace today. There weren't spiders or mud daubers in there, but there were walnut shells! The heat exchanger appears to be in really great shape. I used the air compressor to clean it out.... you'd have thought I was in an Al Jolson look-alike competition! All those years of propane soot blew out and all over me!
On the negative side - the Bosch blower motor is toast, and there's a threaded opening on the front of the heat exchanger with its cover is missing (I'm guessing it's a combustion chamber view glass). I've also figured out that I don't have the floor-mounted ducting needed to mount the furnace. As with so many projects, this one is bigger than it initially appeared.
I also discovered something about those two catalytic heaters: They were installed (a 6k BTU in the living area and a 4k BTU in the bathroom) at some point after the furnace was removed. Must have been a major (owner) mod at some point in the last 40 years.

[Aage]

The threaded opening is where you could manually light the furnace. The cover was not glass, but rather just a metal (steel, I'm guessing) screw-on cap.

If you don't have the one from the original furnace, perhaps someone on the forum would donate one to you, as there have been lots of furnaces ripped out over the years.

The ducting shouldn't be hard to find, any home heating shop, even Home Depot might have a piece...

Walnut shells... So maybe a squirrel was inhabiting it?

Too bad about the motor, but again, shouldn't be impossible to find one.

Might have been fun to see you doing your "blackface" impression. LOL!