Advice for new HVAC system
September 25, 2018 8:39 AM   Subscribe

My twenty-five year old furnace died, and its buddy air conditioner should be replaced too. Looking for general advice.

Obviously, I'll be going for something more energy efficient, but I'd love to hear suggestions for things I might not be thinking of. What general advice to you have? What extras are worthwhile?
Details: I have a good contractor (they put in my water heater, they have great reviews on Angie's List and yelp, and the city inspector said they always do good work), but I think they might be on the expensive side (and might be worth it - how would I know?). Is there a reliable way to find out ballpark figures? Are there different levels of energy efficiency I should know about? How different are they? This is a three bedroom condo, and I'd like to be able to sell in the next ten years, so I don't necessarily want my dream furnace. I do want to be cost conscious. But it occurs to me that there might be some cool things I don't know about. So whatever you've got, throw it at me.
posted by FencingGal to Home & Garden (9 answers total) 5 users marked this as a favorite
If you're factoring in tax breaks on efficient units, make sure you're looking at information specific to 2018.

For a condo, the cost of a highly efficient set of units may not pay for itself in 10 years.

If you live in an area where you can end up needing both A/C and heat in the same day, make sure you get a thermostat that can be set to turn either on as needed rather than being stuck in a single mode.

If you get something that you connect to the internet, make sure they have some indication they at least thought about security. It's great being able to change settings remotely but some of the security mistakes have been dreadful.
posted by Candleman at 8:53 AM on September 25, 2018 [1 favorite]

The energy efficiency of A/Cs is measured by the SEER rating. This is a pretty good review of what it means
posted by The_Vegetables at 8:54 AM on September 25, 2018 [2 favorites]

Definitely get some quotes, they can be all over the place and it's free. We went with a local place that came highly recommended and they did extremely solid work for only a few hundred bucks over the cheapest place. There's a lot of new stuff, California (and other states?) has a duct sealing requirement (HERS). The only thing I would note was that energy efficiency on the furnace was not worth it in any way, and I say that as someone who pays to have all their electricity from solar sources. The basic furnace option was 80% efficient, and it was several thousand dollars more to get a 92% efficient model. 12 percentage points plus it would need a water line was a loser for me.
posted by wnissen at 9:03 AM on September 25, 2018

Before I had central air installed last spring, I looked this site and this site just to get a ballpark figure. (Note, I already had ductwork since my furnace was forced-air.)

The estimates on those pages were pretty close. In fact, on the list by brand on the Homeadvisor site, it shows Lennox as $3400. My actual cost was $3440. Obviously there are tons of variables. For reference, I am in Billings, MT, where these kinds of things seem to be about average cost, and my unit was installed in a cramped crawlspace connected to an existing furnace. I didn't get a super energy efficient unit, as the higher cost wouldn't have been worth it, even with any tax credits. (Even the installation company agreed.) Interestingly, though, my electric bill dropped about 25% running central air vs. my previous multiple window A/C units.
posted by The Deej at 9:10 AM on September 25, 2018

Get quotes from the contractor you've used before, along with a couple of others. The more detailed, the better, and getting them all in a short period of time is useful so you don't have to spend a long time putting off the one you called first while you're waiting for more info from the others.

Most HVAC contractors will be able to handle the paperwork for energy efficiency rebates, and it's common for the rebate to be signed over to the contractor in exchange for an immediate discount in that amount.

Newer and more energy efficient doesn't necessarily mean smaller A/C unit, so be sure that what they're suggesting will fit within the outdoor space available to you. (They should be checking while visiting to prepare their quotes.) If there's any size change expected, you may want to run that by your HOA before installing it.
posted by asperity at 9:21 AM on September 25, 2018

Since you're replacing the whole shebang, you should include a load calculation in the mix. This is especially key to properly sizing the AC to the house. There's an old-school "rule of thumb" that a lot of contractors go by instead of doing an actual load calculation, but it could result in having an oversized/undersized AC unit.
posted by Thorzdad at 9:44 AM on September 25, 2018 [2 favorites]

I had furnace troubles and the company I called for repairs said to replace it. I got a quote from them, and called 2 other companies. Company #3 is the more expensive plumbing company in town. said they could likely fix it, and did, saving me @ 10k. Probably not the case for you, but get several quotes. Also look at the long range; if one system is 10% more efficient, and your fuel bill is X, what's the payback period. If you ever want to add solar, now is probably the time, so check it out; the cost of panels has come way down.
posted by theora55 at 9:49 AM on September 25, 2018

Don't just check for federal rebates or tax credits. When we had to replace our furnace there was a significant rebate from the DC Sustainable Energy Utility that more than covered the cost difference between 80% furnace efficiency and 94% (but going from 14 to 17 SEER on the A/C wasn't worth it at all). And seconding what Thorzdad said, a dedicated HVAC contractor will have access to sizing tools that will result in a more efficient system over the long run, but a general contractor is going to guess or just replace like with like.
posted by fedward at 10:38 AM on September 25, 2018 [1 favorite]

Something else to consider: highly efficient A/C compressors are MUCH bigger (both wider and taller) than older compressors, to the point where you could run into problems if you have a small/constrained outdoor space. Be sure to ask about the physical footprint of the outside unit if you think this will be an issue.
posted by puffyn at 12:27 PM on September 25, 2018 [1 favorite]

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