My furnace and AC are 35 years old and, in addition to being terrifically inefficient, the AC compressor has broken down several times this summer. I want to replace both of them now, before there’s a catastrophic failure. Can anyone recommend brands or specific models? I’m willing to pay more for greater efficiency. I’ve heard that variable speed furnaces are more efficient, but I can’t find information online that doesn’t look like advertising. Is it better to go with a heating and air contractor or go through a big box store (Home Depot, etc.)? Any well known scams to avoid? Do I want some kind of built in filter? Can I wire up the new thermostat myself, or should a pro do it? How do I figure out what size unit I need, since I imagine the salesman will overestimate? Thanks.
I replaced my system three years ago. I’ll share my experience as a consumer, but I believe there are HVAC people on the board, so you should definitely pay attention to them. Can you even buy a system at the store? I’ll admit I didn’t even consider the possibility. I contacted three local firms for estimates to replace my aging system, including the company that had been doing my maintenance. Not one of them would do an analysis of the house to assess my requirements. IIRC, that’s called something like a ‘Manual J’. Anyway, I got hold of the paper for the analysis and did it myself; the results said I needed half the BTU’s the contractors were proposing.
Long story short, I bought a Rheem Criterion II Plus 2 updraft gas furnace from a wholesaler, along with a conversion kit to switch it to propane. (It came from the factory set up for natural gas.) I got this partly because some furnace guys I talked to liked the brand and partly because the stuff I was reading at the time led me to want a spark igniter instead of the hot surface igniters that some of the less expensive models had. The Rheem has a 2-speed fan. I don’t know if that saves me any money, but the low speed is quieter and I like that. The furnace is overall cheaper to run than the old one, but it’s a much newer, more efficient furnace.
Plus, I converted from a downdraft system to an updraft system. The furnace sits in a utility closet (no basement); the old one blew down into ductwork under the house. The new updraft setup uses the old under-house ducts as the air return and I have new ductwork in the ceiling. I had a professional installer do the work on the side. He did everything except the propane conversion and some dip-switch settings on the control board, which I did, along with being his helper during the installation. (So I did simple stuff like building the return plenum, installing vents, mounting the compressor for the a/c, fetching tools, holding the other end of whatever, etc.)
So far, the Rheem has performed flawlessly. I believe going with a lower BTU rating is part of the reason that the temperature fluctuations are much less noticeable now. I didn’t have a/c before, so all I can say about the central air is that it’s nice. It appears that my calculations were pretty good (knock on wood), as the furnace and the a/c have both handled even extreme weather conditions. I certainly don’t recommend that everyone install their own furnace, although it isn’t at all uncommon around here. I want to remind you that I had a professional doing the stuff that needs a professional. And for the a/c, I gave him the base figures to use, but he’s the one that figured out which compressor to use and how much charge to put in, and that’s something that looks easy to screw up. Plus, I’d be surprised to find out you could purchase refrigerant without having some kind of EPA license these days. But being my own contractor and assuming upon myself the risks that go with that saved me a lot of money.
My housemate is an HVACR tech, and he enthusiastically recommends Carrier and Mitsubishi air conditioners. (Mitsubishi makes some nifty things that solve installation challenges that you probably don’t have.)
On efficiency, a higher SEER number is better. The newer systems do a bunch of neat tricks that boost efficiency - some run multiple small compressors in the unit switching them on and off as needed, and some run one compressor, but at variable speeds. As a side benefit, both of these techniques help reduce noise. Your neighbors will appreciate that.
Go with the local guy, and get estimates from at least two different companies. I’d avoid the “big box” deals as they’re just farming out the work to the lowest bidder - it’s all about the price point and bare-minimum effort for them.
A new programmable thermostat should be part of the installation package. I’m not sure what you mean by a built-in filter - there will be a filter in the air handler. Or are you thinking of an electrostatic air cleaner?
As for system size, a general rule of thumb is one ton per 500 square feet. This will vary, depending on the size of your thumb, your local climate, how well insulated your house is and things like south or west-facing windows. Or have a look here for some more detailed ways to find your needed capacity.
Amazingly, it is possible to buy and install your own system. “Package unit” systems are self contained - you just feed them electricty and gas, and hook up return and output air ducts, so they’re simple. These are the things that often get installed in attics. There are also DIY “split” systems - the traditional type where the compressor is outside. No licensing is needed as they’re sold with pre-charged refrigerant lines. You will most likely need a permit from your local building department.
Thanks guys. To clarify, my air handler does not have a filter on it. Instead, there are filters at the 2 intake gratings inside the house. I was vaguely aware that some air handlers have a filtery-looking thing attached and I assumed that it was something used in addition to the inside filters that I’m used to. Are electrostatic filters any good?
A new air handler will most likely have a slot of some sort for filter(s) in it, making your current setup of filters under the return grilles redundant.
Electrostatic cleaners were in vogue some years ago. If you suffer from allergies, they do great at pulling all of the pollen, dust and other icky stuff out of the air, but you need to keep the house closed up for them to be effective. Otherwise, they’re a bit of a maintenance chore as they need to be washed once a month or so. I think some of the new ones can self-wash, but they’re not cheap. For all but the most allergic, they’ve largely been replaced by high-quality pleated filters like 3M’s Filtrete.
Two years ago, we replaced our ancient oil furnace and inefficient air conditioner. We bought a Trane from a local business (the folks we buy our heating oil from) and we have been most pleased. The new system (our old one was over 30 years old) is much more efficient, quieter, and just plain nicer. We’ve had to call for service a couple of times, and they always come promptly and took care of things - all under warranty. I’m pretty sure the good service is because they’re a local company.
And I do like the Trane brand.