Old Gas Furnace, replace now or wait till the end of it?

[Poncho_NM]

Gas furnaces, efficiency matters

Furnaces have generally become more energy-efficient over the years. A typical gas furnace made in the early 1970s has an AFUE of about 65 percent. Today, the lowest efficiency allowed by law for new gas furnaces is 78 percent, and the most efficient models have an AFUE of about 97 percent—or near-total efficiency.

The price of a furnace generally rises in step with its fuel efficiency. A furnace with a 90 percent AFUE can cost about $1,000 more than a similarly sized unit with an 80 percent AFUE. However, that additional cost can generally be recouped in lower fuel bills over the lifetime of the furnace. Just how quickly the investment is recovered, though, depends on more than the difference in AFUE between the two units; the electrical bills to run two furnaces with different AFUEs can differ significantly. Payback times will also be affected by the climate where you live, how well your home retains heat, and the rates you pay for gas and electricity.

The entire article is worth reading.


An other article worth reading: What Do Furnace Efficiency Ratings Mean? From Angies List

[chet everett]

I have found the price differential between a the "tip top in efficiency" and the "midline" for an entire HVAC system to be MUCH than higher just $1000 AND my experience is that midline unit is FAR LESS LIKELY to need repairs as well as having very modest difference in operational costs. This is borne out by friends that operate HVAC firms -- they simply get far fewer call back for the systems that are around 80-85% efficient than those over 95%. There are some exceptions to this "rule", like in areas with unusually high gas prices, but that is easy to determine -- https://www.yourmoneypage.com/energy/furnace1.php

Natural Gas Prices - Energy Explained, Your Guide To Understanding Energy - Energy Information Administration

[btuhack]

Originally Posted by chet everett

It is frankly a WASTE OF MONEY to "proactively" rip out a functioning furnace.

False.

A) Replacing today will be cheaper than this time next year. Aside from rising equipment and labor costs, a furnace swap in my region costs $800-1000 more this year due to compliance with new state regulations
B)The sooner you replace the furnace and address all the other usual concerns, the sooner you start saving on the utility bill.
C)Old furnaces are inherently more dangerous.

I looked at a 32 year old furnace this afternoon. Whatever the problem was over the weekend wasn't malfunctioning today so that mystery remains. I was able to get the carbon monoxide production down to 30ppm with 100 ppm being the upper limit for "safe" operation. It was producing 850 ppm on my arrival.

[btuhack]

Originally Posted by Poncho_NM

The entire article is worth reading.

Those articles weren't great.

A condensing furnace is a bad investment in mild climates...the roi simply isn't there. Also, everybody gets hung up on equipment efficiency and think that's what they get, well it isn't. A 30 y/o duct system generally leaks a lot and a 95 % efficient furnace might deliver only 65% of the heat with the balance being lost to attics and crawl spaces. Money spent on getting the duct leakage as close to -0- is the best investment.