are newer furnaces more efficient?

[Tony Hwang]

Hi, My furnace came with 10 year P&L warranty plus heat exchanger is on life time warranty.

[dpb]

I'm also in the camp of I'd have to see actual data that shows a negative rate of return over a longer period to believe it true as a general statement.

[FrozenNorth]

My 16 year old furnace gets an annual cleaning and inspection as part of an annual maintenance agreement, for less that $250 a year, that has saved me many dollars on several occasions when parts went sideways.

[Ed Pawlowski]

A 1998 furnace is probably not more than 85% or so but I'd have it checked to be sure.

You may get a better return stopping some of the leaks though. It can get expensive replacing doors and windows, but covering existing windows, insulating, and spray foam have a quick payback.

[bob_villa]

Our Carrier, that I put in '95, is 92% efficient.

[micky]

Okay. I guess they measure unburned hydrocarbons. Now that I think about it, isn't that what they measure when the put a probe in the car's tailpipe? Something they don't do if your car is new enough, of if you are old enough and don't drive more than so much, or if you live where air polution is not so big a problem.

[Ed Pawlowski]

That's pretty good. Not worth an upgrade unless it needs replacing at some point.

[Tony S.]

Think of it this way. On a 80% efficient furnace, 20 cents of every dollar is wasted. On a 95% efficient furnace, 5 cents of every dollar is wasted. Have your friend figure out what the savings would be by their fuel bill.

[gregz]

I don't see how that's possible, unless an extra ambient air heat exchanger is used. I never measured a system. If incoming water is heated by another pre exchanger with output of main exchanger, the flue gas will be closer to incoming water temp.

Greg

[micky]

Gas furnaces have nothing to do with oil furnaces. You must be misrecalling the discussion years ago, which was also about oil furnaces.

Thekmanrocks brought up the subject of oilf urnaces.

[trader_4]

No, I was just thinking in the context of this current thread, which started with a question about the efficiency of gas furnaces. I missed the segue into oil furnaces. But even so, there are condensing oil furnaces that are as high as 95%, Adams Manufacturing has one for example, though they may not be mainstream or practical. IDK what they cost.

[micky]

I mentioned those but "condensing" is the word I couldnt' think of. I suggested Retroactive, incandescent, and self-descending, (At least I got the c and sometimes the n,)

I r ead that they are expensive and not often sold, I don't know how expensive, but no one who came out to sell me a furnace even mentioned one.

[trader_4]

I guess a good question is why? The essence of it should be a larger, better heat exchanger to extract more of the heat. I wonder if something bad happens with an oil burner when you cool the gasses that much, like some nasty gook forms, that you don't get with nat gas? But on the other hand, at least some companies are building them, up to 99%, so IDK....