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  1. #1
    Join Date
    Jul 2005
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    I live in Canada and I am considering replacing my old Smarts furnace (1976) with a new oil furnace (AFUE 80-85%). According to the last service, the current furnace has an effiency rating of 79%. This seems high for a 30 year old furnace with an flue exit temperature at 450 - 500 degrees F. I think the furnace has reached the end of its life as soot is being noticed upstairs on the walls and around the furnace.

    There are so many out there and so much information, I am getting confused. I just had an energy evaluation done with a design heat loss of 53835 BTU/H. How important is this when considering the size of a furnace ? The installer is suggesting a 77000 BTU/H to a 89000 BTU/H.

    Which are the better and best oil furnaces ? I have been looking at the Newmac NL2 lowboy (84.8 AFUE) and Olsen BML lowboy (85 AFUE). Which is better ? Should the newer oil furnaces come with a barometeric damper as I was told that the newer furances do not or should not come with one ?

    Is there any other information I should consider ?

    I would appreciate any information or advice.


  2. #2
    Join Date
    May 2000
    Indianapolis, IN, USA
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    Here's a couple things on efficiency. Today's equipment is rated at annual efficiency which looks at startup & cooldown inefficiencies plus standby loss. When they say 85% they mean 85% of the heat you pay for heats the home over the course of the winter. The 79% figure given you for your old relic is combustion efficiency. Means that when fully warm under perfect conditions, 79% of the heat stays in the house, 21% goes up the chimney. But annual efficiency when you figure how long it takes to get fully warm, losses during cooldown & standby, is probably 55-60% on something of that age. So you can't compare the 2 figures.

    Never heard of Newmac. We've sold some Olsen with good results. They make for other brands such as Nordyne & York. Don't oversize. If you need 54K, find a furnace with output right at or just above that figure. It isn't efficient to oversize!

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