New Furnace BTU size for 31ft trailer

[Kstar]

Hi,
I have a 1979 31 ft. Airstream and was wondering what size furnace to put in. I see at Camping World they have three different BTU sizes available, 24,000, 30,000, and 34,000. I believe mine has a 24,000 in it now. I do live in a colder climate and I like to travel into the mountains where it gets down to 30 degrees and colder.

Thanks,

Kent

[Inland RV Center, In]

Kstar

The Suburban NT-30 SP is more than adequate for your Airstream.

The original size in your trailer was 30,000 BTU.

Andy

[mcneon]

Kent, check the data plate on your current furnace carefully. Older furnaces were often rated according to BTU output, while newer ones are rated for their BTU input. I don't know when the change in rating method was made. (The original furnace in my '74 Argosy was output-rated)

Since RV furnaces are probably no more than 80% efficient, the difference is a big number in actual heating capacity. You might need a 30,000 BTU unit to replace your older 24,000 if this is the case.

Example: an older 24,000 BTU furnace (rated by output) is putting out 24,000 BTU worth of heat while consuming 30,000 BTU. The remainder is lost through the exhaust. A newer 24,000 BTU furnace (rated by input) is consuming 24,000 BTU worth of gas, but will only give you 19,200 BTU in usable heat.

Bob in Nashville

[Darol Ingalls]

The 34K unit will fit in the same space as your current furnace and the price is should be the same for all three sizes. If not, the dealer is taking advantage of you. Get the large one since you'll be out in the cold. The larger furnace will heat the trailer faster and run less than the lesser capacity units. If possible, run another heat duct from the furnace (there are four possible connections) to part of the trailer that currently does not get heat directly. The 34K BTU is the input rating. Sure would be nice to capture some of the heat from the exhaust port but I haven't been able to figure out how to do that, yet. Darol

[toolman5252]

Originally Posted by Darol Ingalls

The 34K unit will fit in the same space as your current furnace and the price is should be the same for all three sizes. If not, the dealer is taking advantage of you. Get the large one since you'll be out in the cold. The larger furnace will heat the trailer faster and run less than the lesser capacity units. If possible, run another heat duct from the furnace (there are four possible connections) to part of the trailer that currently does not get heat directly. The 34K BTU is the input rating. Sure would be nice to capture some of the heat from the exhaust port but I haven't been able to figure out how to do that, yet. Darol

up here, when we build a wood stove out of a oil drum , we make something called a stack robber that captures the exhuast heat from the stove and actually makes more heat than the stove it sits on. I also have been trying to figure a way to do that with a propane unit, probably one of those projects that need me to get cold once or twice more to start taking shape , bob

[davidz71]

My '77 Excella 500 31' had a 30,000 BTU unit and like Andy said it is more than adequate in keeping the trailer warm. My '86 25' Sovereign has a 34,000 BTU unit in it. I guess it all depends on the price difference between the two. If the difference isn't much, go for the 34,000 BTU for the extra warmth should you ever need it in cold weather.

[Mike76251]

AS LARGE AS WILL FIT.
The insulation in Airstreams' is great BUT.....Aluminun outer skins connected the Aluminum inner skins via Aluminun ribs conducts heat out faster than you can believe.
20 year full timer in a Airstream.

[Wardinbb]

Unfortunately, the different size units don't cost the same. But this guy here is offering a great deal on an Excalibur 8535 with a door! With the amps stated, I suspect it's last year's model, but $200. saved or found may make this item attractive.
http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWA%3AIT