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Old 12-03-2015, 02:58 PM   #1
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1971 21' Globetrotter
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Furnace replacement for 1971 Globetrotter

Hi, this is my first post...
I own a 1971 Globetrotter. It's 21 ft long with the interior of the cabin at about 17 ft. As you can imagine there is very little (if any) insulation so the heat loss is quite high.

On that note, I'm in need of a new furnace. The current model, that is no longer working properly, is the NT-16F (no longer available from what I can see). The BTU rating is 16000.

I am considering installing a new furnace, the NT-20SQ which has a BTU rating of 19000. It looks like an obvious choice. That said, I am planning on using the trailer through the winter as an onsite office and occasional crash pad. With the sub zero temperatures in these parts I am debating whether or not I should consider a larger furnace - thinking of the NT-30 SP.

I'm not sure if I am missing any obvious considerations.

Any advise on which furnace would be the best choice, including any I haven't considered, would be greatly appreciated.

FYI, I also have shore-power of 30 amps so I can use a space heater if necessary.
Thanks
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Old 12-03-2015, 03:21 PM   #2
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If you are not paying for electricity, the space heater is the obvious choice. Due to the minimal insulation and high thermal conductivity of your trailer, heating it will be costly and you will burn a lot of propane in sub zero temps.
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Old 12-03-2015, 03:40 PM   #3
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The various forced-air furnaces have minimum outlet area requirements... without some mods I'm guessing you don't have enough vents/outlets in the trailer now to meet the requirements for the NT30 which is big enough for a large trailer, it's only the longest couple of models that get multiple furnaces. For having propane heat it'll probably be best overall to go with the NT20 or maybe one of the alternate brands. The NT will fit right up to the existing exhaust/intake holes in the outer skin, though it may require you to build a base for it if the new case is a different shape than the old.

You should be able to find the duct/outlet area requirements for each model at the manufacturer's website to get a definitive answer.
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Old 12-03-2015, 07:09 PM   #4
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The NT 20 will work out fine in the small trailer you have.
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Old 12-03-2015, 07:23 PM   #5
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In my 71 25' Tradewind I replaced the old furnace with an NT30. You may have to make some modifications so that the new furnace combustion air and exhaust holes line up with the corresponding furnace holes.

For sub zero I don't know if a NT20 has enough juice for winter weather. In any event you will burn a lot of gas and have to address condensation issues inside the trailer.
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Old 12-03-2015, 08:09 PM   #6
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My son just installed an Atwood 7916 in his 67 20' GT. It's a great compact furnace, replacing the original one that was much bigger and heavier. Jim


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Old 12-04-2015, 09:39 AM   #7
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Thanks for the great info. With the advice I've read, before committing to the NT 20 (which seems to be a better choice over the NT 30) I will look at the Atwood brand. In addition to having the furnace and space heater, I am installing a 2ft X 4Ft 800 watt infra panel on the ceiling. Infrared heat might keep some of the condensation down but will have to wait and see. Thanks for bringing condensation to my attention - no doubt it will factor in and will need to be addressed. Thanks again!
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Old 12-04-2015, 02:27 PM   #8
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Quote:
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I am installing a 2ft X 4Ft 800 watt infra panel on the ceiling.!
Sounds interesting can you post some more info.
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Old 12-04-2015, 03:47 PM   #9
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If you have 30amp power, is your AC capable of having a heat strip installed as a supplemental heater?
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Old 12-04-2015, 04:26 PM   #10
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Not sure if a heat strip can be installed aftermarket, but 30 amps will run it.
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Old 12-05-2015, 12:21 PM   #11
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The infrared panel I plan to install is the "Base IR200 - 800 Watt Standard Heating Panel" which can be seen at irheating.ca.

I have a clean 30 amps running to the trailer. Currently I am using a small space heater that has the typical settings of 750 & 1500 watts. It works well at either setting. I am also powering other small electronic devices and lights. So far no problems with power.

There is just enough room on the ceiling next the AC unit to mount the 2ft X 4ft infrared panel. There are optional mounting brackets for the ceiling but I am reluctant to drill into the interior. I have an approach I believe will keep the original interior intact without drilling holes.

Once installed I'll post some photos. Cheers
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Old 12-05-2015, 08:56 PM   #12
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Hi Fraser and welcome to Air Forums. It's a great place to get advice from experienced Airstreamers who have likely done what you want to do.

It will be challenging to keep your Globetrotter warm in sub zero degrees C temps. Old Airstreams are not as well insulated as the new ones, and Airstreams are not the greatest cold weather campers around.

Here is my story. I installed a NT30 in my 1966 24' Trade Wind. The installation instructions are very specific on the amount of vents you must use to exhaust the hot air, and getting cool air back to the furnace. My old trailer had this strange system from the factory where cold air was drawn to the furnace via floor vents and ductwork under the floor. The hot air exhausted out one big vent in front of the furnace. I did not want to install a flexible above floor 4" vent through the cabinets and under the bed beacuse I loose valuable storage space.

So I decided to reverse the hot air flow. I delivered hot air to the floor ducts and floor vents via an underfloor plenum, and draw cold air into the furnace cabinet in the galley. I also had to heat my under the floor waste water tanks. So I had lots of places to vent hot air. Bottom line is my system is inefficient, but it keeps the trailer warm, including the rear bath.

A new furnace install is a fun project. Maybe you can read the installation instructions on line to insure the NT20 or Atwood will work okay in your Toronto winters.

David
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Old 12-05-2015, 09:28 PM   #13
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Quote:
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It will be challenging to keep your Globetrotter warm in sub zero degrees C temps.
David
Being in Canada I would guess Fraser is talking about sub zero fahrenheit not celsius which is a whole other kettle of frozen fish.
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Old 12-06-2015, 10:36 AM   #14
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Hi David, thanks for the additional info. I realize heating the AS in the dead of winter, especially up here in Canada will be a challenge. The subzero temps can be as low as -25C but usually not much lower than -15C.
I am leaning towards installing the NT20, which as I mentioned is an upgrade from the current smaller model, NT-16F.
The pics of your NT30 installation are very helpful. Based on your approach I might be in a position to consider something similar when the warmer weather permits a more elaborate retrofit.
My Globetrotter has a duct system already in place. It needs to be reworked as there are many gapping holes and other deficiencies to address. All things considered I will likely simply do a straight swap if the new NT20 allows.
I'll be sure to read the installation instructions as you suggest. Thanks
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