Need recommendations

Old 09-17-07, 11:20 AM
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Need recommendations

We just completed a full year in our new home, built around 1991-2. I have a HUUUGE, highly inefficient furnace - Carrier, 175,000 BTUs, 80% efficient with an 8 inch flue. It is heating a 3300sf home in Chicago, and has been for about 15 years. My gas bill in February was $450. The furnace is in the center of the basement, with ductwork going left and right to both floors.

I am looking at replacing the furnace before it gets cold, hopefully taking advantage of the tax benefit while I'm at it. I figure that an efficient furnace will knock down the cost of the bills enough to make it worth replacing now instead of 3-5 years from now, when it will likely die.

I talked to a reliable furnace guy, and he gave me 3 options. He said that there isn't much made that will accomodate the size of my home and the power and input of my A/C.

First, he suggested a 93% efficient Rheem model to replace what is there at a cost of around $3500.

Second, he suggested but didn't recommend piggybacking 2 smaller furnaces within the existing ductwork.

Third, he suggested 2 furnaces and 2 a/c units, which is what the original builder should have done. However, it is not possible to do this properly, with each unit heating a floor, without ripping out lots of ductwork. However, it is possible to split the house left-right and have a unit serving each side. This is probably the best way to solve the unbalanced heating issues, as the thermostat is on the south, right side in a protected area, while the heating problems are on exterior, northern walls on the left side, with lots of windows. HOWEVER, the cost to do this is around $10,000 - not out of budget, but questionable as to whether we can recoup the costs over the long term. I don't expect to move, so that isn't an issue.

So, if it was your house, what would you do? What do you recommend?
Old 09-17-07, 06:20 PM
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The first thing I would do is to perform a manual J heating & cooling load calculation. There is a very good program available online for around $50.

The idea of splitting the house sounds reasonable. A big plus to this approach is if one system goes down, at least you have some heat. It may not be comfortable but it is certainly better than nothing & may prevent a freeze-up.

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