90%+ 2-stage Furnaces - Worth the $$?

[Mike Bonkalski]

The fan unit in our 20yr old furnace gave up the ghost so we decided just to replace the furnace with a new more efficient model.

HVAC installers have given us quotes on both 80% and 90%+ effcient furnaces. The price difference is quite a bit. Is it worth it?

[turbo6bar]

Dunno about gas furnaces, but A/C units with higher SEER ratings generally have more complex equipment and electronics. In the event of a repair, the increased complexity = higher repair bill. While a 90% efficient unit would give you the best economy, consider the fact an 80% efficient unit will likely be miles ahead of your 20 yr old furnace. In my opinion, you'll see a very noticeable decrease in your heating bills with the 80, assuming your house is insulated well.

If you plan to stay in your current home for a long time (at least 7-10+ years), then consider the 90% efficient unit. Otherwise, my money would be on the 80%. I just don't believe the cost savings are worth the up front investment. If you've got money to burn or you wish to be more enviro-friendly, then by all means go 90%.

BTW, if your house is not insulated well, buy the 80% unit, and spend the savings on better/more insulation.

Just my opinion,
Jürgen

[RickM]

I hade two new NG furnaces and Central AC units put in a couple of years ago. The HVAC guy said he had the same output units in his home as I and saw very little difference in his electric bill. He knew he could have sold me the higher efficiency models but said it was not worth it.

[turbocarrera]

Depends how long you plan on staying in the house. I just had a energy assesment on my house(part of trying to meet Canada's Kyoto commitments) and the payback period for my new furnace is 8 years(I have a very old house with a boiler heating system). I'm combining that with better insulation in my attic(with better ventilation too) and insulating my basement walls. The total payback period should be about 6-7 years, but I suspect that it will be considerably less with the freaky rise in natural gas prices. Should also save about 8 tons of greenhouse gas emmisions from my house alone, per year. Just a guess here but, I think the 90% furnace is the better deal if you plan on staying there for 5 years or longer.

[RickM]

Originally posted by turbo6bar
Dunno about gas furnaces, but A/C units with higher SEER ratings generally have more complex equipment and electronics. In the event of a repair, the increased complexity = higher repair bill.
Just my opinion,
Jürgen

Excellent points, Jurgen.

Another factor in my decision was a unit which used mostly off-the-shelf, proven replacement parts. However, at the time, the scroll compressors were pretty unique (can you say whipple supercharger ). I think a few brands use them now.

[john70t]

Never researched it, but you can get infrared photos taken of the house to see where the heat/$$ are leaking out.

Double paned window on the windy side and a few hours of caulking will slow down air drafts- a big factor in heat loss.