Or ...if you know an unbiased source to research.
I recently installed a new furnace in a second home in the mountains and did a lot of research. I first did a search on who makes what brands, because it’s really hard to tell these days. Only a few manufacturers, but a host of brands. There’s a website that lists who makes them and rates them, too (I didn’t keep the link, but I found it on a Google search). Rheem and Goodman make their own, if I remember correctly. One thing came out clearly: they all seem to be more cheaply made now than in the past; so I would ignore the people who say they’ve had a certain brand for the last 10-20 years with no problem. There’s almost no chance that if you bought that brand today, you would be getting the same product or quality that the old furnace represents, and possibly not even the same manufacturer. So here’s what I remember concluding: avoid two-stage furnaces—they are more complicated and therefore break more easily and are not really necessary (but a variable fan is good and a thermostat that will let you run the fan when the furnace is not on to evenly distribute the heat is more important); you pay a lot more to get a 96% efficiency furnace than a 92% one, and it’s not likely to pay you back, so go the cheaper route; you don’t want to undersize or oversize the furnace for a lot of reasons I won’t go into, so carefully do the measurements, or have someone else do them, to properly size what you buy; some of the more heavily promoted brands are some of the worst, like York, and the most expensive brands are not necessarily any better than some of the more modestly priced brands; every brand has a share of poor ratings, but I think a lot of complaints registered about furnaces online are probably due to poor installations, or improperly sized units, and not due to the furnace itself—make sure you have plenty of cold air runs situated where they will draw warm air through the areas you will be spending a lot of time in (maybe you’re stuck with what you have now anyway); install a much larger and better filter in the cold air return by the furnace—almost all filters that come with the furnaces are undersized and don’t filter out small particulates. A good installer that you can really trust solves a lot of these issues, but it’s hard to know. Good luck.
...The two major manufacturers of gas furnaces are United Technology (Carrier, Bryant, Heil, Tempstar, and Comfortmaker brands) and Goodman (Janitrol and Amana). Other brands include Rheem (Ruud), American Standard (Trane), and Lennox (Armstrong). All offer furnaces in a range of capacities and efficiencies, and we think manufacturers generally deliver on those specifications. Each brand offers a generally similar array of key features.
The degree of similarity between manufacturers’ offerings is one reason this report does not include Ratings of furnaces by brand. The most important steps in selecting a furnace, we think, are to ensure that the unit’s specifications fit your needs, that it is bought from a contractor who installs it well, and that it’s adequately maintained. Our survey results help confirm that view: When we asked about the most common reasons for service calls for furnaces, about twice as many contractors we surveyed cited human error—inadequate maintenance, for example, or improper installation—as cited defective equipment...
The thing to watch out for is that every brand has essentially three lines of furnaces: premium, budget, and contractor grade. Avoid all furnaces, regardless of brand, except the premium. You’ll pay more, but it’s not gonna need fixing every 3-4 years.
BTW, here’s the best set of reviews on the Internet:
http://www.hvac-for-beginners.com/furnace-ratings.html