| Re: [GMCnet] GMC furnace [message #169193 is a reply to message #169145] |
Thu, 10 May 2012 19:41   |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
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| Rick wrote on Thu, 10 May 2012 11:52 |
I'm new to this forum and to the GMC so I hope this makes sense.
My new(old) '74 Painted Desert has a bad furnace (located under the kitchen sink).
I'm not sure what the brand or model it is, though I suspect it is a Suburban.
What brand and model would be the best replacement? And is there anything special required to compensate for the curved exterior wall. ...
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Welcome to the nut-house! 
As you stated in another message, the Suburban "NT" models are almost direct replacements for the original furnace. The newer furnaces need some modifications to fit. BUT as the are a little smaller, so it is easier than it could be.
As for BTU size, it has been argued that bigger is not always better due to furnace cycling issues. You might get better results with a smaller (BTU) model over a larger one... besides being cheaper to buy.
Yes, there is "special requirement" to compensate for the curved exterior wall. The "NT" models are designed to be placed directly against the wall for cooling air-flow reasons. You can mount it on a slanted base (tilting it to match the wall) or put a metal "back" on the new furnace. (I understand Suburban makes a kit for this.) I have done it both ways and think the level mounting with metal back is the better way to go -- due to space usage and ease of furnace servicing. (I could NOT take my Birch's furnace out due to the tilted mounting.)
If you do NOT tilt the furnace, make sure the final intake and exhaust tubes are long enough to make a good seal.
Here are pictures:
This is someone else's with a nice angled base (much better than mine):
<http://www.gmcmhphotos.com/photos/g6020-suburban-furnace-replace.html>
This is my '73 with a homemade metal back on a level base (You might notice that I am a wood butcher... and not a metal worker. But you get the idea...)
<http://www.gmcmhphotos.com/photos/g3995-furnace.html>
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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