What is routine maintenance for an HVAC system?
February 10, 2025 2:28 PM Subscribe
There are a lot of advertisements for yearly checkups or routine service for heating/air conditioning units. What is this and is it really necessary?
Best answer: In theory, it's changing filters, spiltting and cleaning the condenser fins, maybe gauging up and checking subcooling and/or for clear sight glasses, and visually checking a bunch of other stuff.
In practice, it's probably a hasty filter change and a lot of "rest looks good".
posted by Rhomboid at 2:48 PM on February 10 [4 favorites]
In practice, it's probably a hasty filter change and a lot of "rest looks good".
posted by Rhomboid at 2:48 PM on February 10 [4 favorites]
Best answer: Our heater started having issues just before Thanksgiving, just as we were having our first really cold weather here. It would seem to be starting up, then just...not. We bought the house in 2023 and were assured that things were fine during the inspection, so we thought it might be the thermostat. Still, I called the company from the sticker on the HVAC housing, and paid the service call.
It was cleaning; it hadn't been cleaned in years apparently and in places that the home inspector wouldn't see unless removing panels (which they do not do). The technician was nice, he showed me how to remove the panels and look at the igniters (some rust) and the cobwebs inside the housing (!). We had been replacing the filters and keeping the area clean, but there was so much dirt inside it was keeping it from working properly. We'd also been told the humidifier unit needed replacing, but the technician was able to point out it hadn't been opened /cleaned properly, and got it working fine. He was able to find the production date for the unit, so we have a better idea of potential life span than just guessing that it's newish...?
I definitely plan to have it serviced again in the spring before A/C season kicks in. Like JoeZydeco, I'd rather get the service package than have things get weird around a holiday weekend, especially now that I know how old our unit is and what kind of care it had/didn't have.
posted by winesong at 3:01 PM on February 10 [1 favorite]
It was cleaning; it hadn't been cleaned in years apparently and in places that the home inspector wouldn't see unless removing panels (which they do not do). The technician was nice, he showed me how to remove the panels and look at the igniters (some rust) and the cobwebs inside the housing (!). We had been replacing the filters and keeping the area clean, but there was so much dirt inside it was keeping it from working properly. We'd also been told the humidifier unit needed replacing, but the technician was able to point out it hadn't been opened /cleaned properly, and got it working fine. He was able to find the production date for the unit, so we have a better idea of potential life span than just guessing that it's newish...?
I definitely plan to have it serviced again in the spring before A/C season kicks in. Like JoeZydeco, I'd rather get the service package than have things get weird around a holiday weekend, especially now that I know how old our unit is and what kind of care it had/didn't have.
posted by winesong at 3:01 PM on February 10 [1 favorite]
If you're asking for the purpose of learning what you might need to do for your own HVAC system, what kind of system do you have? There are a variety of technologies and fuels, especially for heating, and they need different kinds of maintenance and service.
posted by dreamyshade at 3:03 PM on February 10 [1 favorite]
posted by dreamyshade at 3:03 PM on February 10 [1 favorite]
Response by poster: I have a heat pump type system and have no plans to do anything except look after filters. I just don’t know if all of this routine maintenance advertisement is worthwhile. It's starting to sound like it may be.
posted by mightshould at 3:20 PM on February 10
posted by mightshould at 3:20 PM on February 10
Best answer: Heat pump owner, too. I think it’s worth it. I assume you have a traditional heatpump (the ones that look like oversized AC units.) If so, you still have the inside air-handler/heat exchanger that needs to be checked/cleaned. They should also make sure the emergency/auxiliary heat coils work. Having the coolant pressures checked twice a year (because it’s a heatpump) is nice, too.
The quality of the checkup does seem to depend on the tech doing the work, though. But, that’s pretty much true about any trade these days.
posted by Thorzdad at 3:32 PM on February 10
The quality of the checkup does seem to depend on the tech doing the work, though. But, that’s pretty much true about any trade these days.
posted by Thorzdad at 3:32 PM on February 10
Best answer: If your heat pumps are ductless mini-splits, routine maintenance is absolutely a good idea. More than just cleaning the filters, you'll want to clean the fins on the indoor units at least annually (twice a year is better), and clean/inspect the fan and condensation drip pan in each indoor unit. Especially in more humid climates and if the units have been primarily in cooling mode (like, during the spring/summer/early fall) they can have a tendency to build up mildew or mold. It's important to keep these clean, so you're not blowing air around with a contaminated fan. The outdoor compressor/exchanger unit should be cleaned at least annually (better if twice), making sure the fan and exchanger fins are clean and free of debris.
Generally, better companies will run some performance tests on each indoor unit, to make sure they are heating & cooling at anticipated capacity, and will also check for refrigerant leaks.
If you have a central forced-air system, ducts should be cleaned periodically, filters should be replaced, and with natural gas/propane systems, inspections to ensure the furnace air intakes and exhausts for combustion gasses are maintained. The house should be tested for carbon monoxide (CO) at several points.
The local HVAC company who installed our ductless mini-splits did a twice-a-year service, and while they were indeed thorough and not just "yeah it's fine"-ing their way through it, in the end, I do not feel like I was really getting my money's worth, and have since taken over that maintenance myself. There are plenty of useful products to help the DIYer, and there's probably a YouTube video showing exactly how to perform the routine cleaning & maintenance for your units.
Just make sure to throw the breakers and/or use the service disconnect to cut power, before beginning any maintenance!
And speaking of carbon monoxide, here's your friendly reminder to check, test, or replace your home smoke detectors, and also to make sure you have enough installed per current guidelines. They have models now with 10-year lithium batteries, and will alert to smoke AND carbon monoxide. You can get the traditional ionization smoke detector, or the newer type that uses photointerruptors and is a bit more resistant to cooking false alarms, or both. What's the difference? (Also, check/test/add to your home fire extinguishers, too!)
posted by xedrik at 4:09 PM on February 10 [3 favorites]
Generally, better companies will run some performance tests on each indoor unit, to make sure they are heating & cooling at anticipated capacity, and will also check for refrigerant leaks.
If you have a central forced-air system, ducts should be cleaned periodically, filters should be replaced, and with natural gas/propane systems, inspections to ensure the furnace air intakes and exhausts for combustion gasses are maintained. The house should be tested for carbon monoxide (CO) at several points.
The local HVAC company who installed our ductless mini-splits did a twice-a-year service, and while they were indeed thorough and not just "yeah it's fine"-ing their way through it, in the end, I do not feel like I was really getting my money's worth, and have since taken over that maintenance myself. There are plenty of useful products to help the DIYer, and there's probably a YouTube video showing exactly how to perform the routine cleaning & maintenance for your units.
Just make sure to throw the breakers and/or use the service disconnect to cut power, before beginning any maintenance!
And speaking of carbon monoxide, here's your friendly reminder to check, test, or replace your home smoke detectors, and also to make sure you have enough installed per current guidelines. They have models now with 10-year lithium batteries, and will alert to smoke AND carbon monoxide. You can get the traditional ionization smoke detector, or the newer type that uses photointerruptors and is a bit more resistant to cooking false alarms, or both. What's the difference? (Also, check/test/add to your home fire extinguishers, too!)
posted by xedrik at 4:09 PM on February 10 [3 favorites]
I have an older heat pump and just realized it was manufactured in 1991. It is still running okay. I cleaned out the leaves that blew into the outside unit and replaced a fan capacitator that had gone bad. I've just scheduled an HVAC maintenance visit because isn't that what you do? I haven't had it fixed in about five years or so, plus we use a pellet stove most of the time. I think I will cancel the visit because what will they do besides poke around and tell me it seems to be running okay for a 33-year-old heat pump?
posted by diode at 6:51 PM on February 10
posted by diode at 6:51 PM on February 10
The company that I have a contract with for these routine services -definitely- prioritizes the contract customers for service during storms/HVAC-challenged events, which has some value on top of the deeply enjoyable hour I get to spend with my pad Rodney twice each year.
posted by janell at 8:43 PM on February 10 [2 favorites]
posted by janell at 8:43 PM on February 10 [2 favorites]
What kind of HVAC system? I’m in New England with an oil furnace. It requires annual cleaning to operate effectively, efficiently, and safely. Gas systems might not need so much attention, and other systems will vary.
posted by theora55 at 6:23 AM on February 11 [1 favorite]
posted by theora55 at 6:23 AM on February 11 [1 favorite]
Best answer: I have a gas furnace and a gas hot water heater. Although not an answer to OP's question, I agree with janell above, that having a yearly contract gets their attention over random callers during storms. They also stock parts known to fail in the equipment used by their customers. Lesson I learned when I moved in to my current home. FWIW.
posted by forthright at 9:24 AM on February 11 [1 favorite]
posted by forthright at 9:24 AM on February 11 [1 favorite]
Just for the public record since this doesn't apply to the asker's heat pump: if you have a gas-fired system, routine maintenance is part of what identifies issues before they turn into, say, a cracked heat exchanger with a continuous carbon monoxide leak. There are other efficiency benefits (getting dust off fan blades, etc etc), but really, avoiding poisoning yourself or others with CO is a really good idea.
Signed,
Someone who was very sick for three months from undetected low-level CO poisoning at their apartment because the landlord didn't understand that HVAC service needs to be an annual activity, not a penta-annual activity.
P.S. It turns out the US building-code compliant CO alarms don't go off unless you exceed a certain threshold for a certain time period -- but extended exposure below that threshold can still make you plenty sick!
Anyway, aside from all that, annual service helps avoid problems so you're not the poor sap with a broken system during a cold snap or a heatwave, waiting miserably for the HVAC company to squeeze you in and send out someone getting paid double time.
posted by cnidaria at 5:09 PM on February 11 [2 favorites]
Signed,
Someone who was very sick for three months from undetected low-level CO poisoning at their apartment because the landlord didn't understand that HVAC service needs to be an annual activity, not a penta-annual activity.
P.S. It turns out the US building-code compliant CO alarms don't go off unless you exceed a certain threshold for a certain time period -- but extended exposure below that threshold can still make you plenty sick!
Anyway, aside from all that, annual service helps avoid problems so you're not the poor sap with a broken system during a cold snap or a heatwave, waiting miserably for the HVAC company to squeeze you in and send out someone getting paid double time.
posted by cnidaria at 5:09 PM on February 11 [2 favorites]
So many reasons for routine HVAC service. As janell suggests, having the agreement in place can grant priority on service calls when it really counts.
In our case, a regular six-month check-up showed a small refrigerant leak. The technician suspected it was the condenser coil. He refilled the refrigerant, scheduled himself 30 days later, and saw the same leak. Having traced the leak to the condenser coil, he discovered that we were still about a week inside the warranty period for this part. Savings: $750!!
posted by John Borrowman at 8:12 AM on February 12
In our case, a regular six-month check-up showed a small refrigerant leak. The technician suspected it was the condenser coil. He refilled the refrigerant, scheduled himself 30 days later, and saw the same leak. Having traced the leak to the condenser coil, he discovered that we were still about a week inside the warranty period for this part. Savings: $750!!
posted by John Borrowman at 8:12 AM on February 12
The big question is how well you can tolerate an outage. For me, a unit going out in high summer with 98 degrees temps and two people working from home would be a major, major problem. Especially with the added hassle of finding someone to come on a Sunday, etc. Our maintenance folks run all sorts of load and voltage tests and inspect the outdoor and attic units, spending over an hour. They don’t do the filters because I already do that. It’s easy and I can buy the cheap but good ones I want.
It’s just like having a car - you can just never take it in and it’s all good till a belt breaks or you have some other urgent surprise. I hate surprises. Also - tell them up front you don’t want a new unit, duct cleaning, UV attic lights , or any of that. Ours got the message and the very friendly guys just come do the work .
posted by caviar2d2 at 9:06 AM on February 12
It’s just like having a car - you can just never take it in and it’s all good till a belt breaks or you have some other urgent surprise. I hate surprises. Also - tell them up front you don’t want a new unit, duct cleaning, UV attic lights , or any of that. Ours got the message and the very friendly guys just come do the work .
posted by caviar2d2 at 9:06 AM on February 12
Also, since filters are cardboard, write “changed MM/YY” on the downward facing side in sharpie when you put them in.
posted by caviar2d2 at 9:07 AM on February 12
posted by caviar2d2 at 9:07 AM on February 12
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The furnace checkup involves cleaning the heat exchanger, checking the heat exchanger for cracks and leaks, measuring the output gas for CO, looking at the efficiency of the unit. There's usually a free air filter in there as well.
A/C involves pretty much the same thing as well as measuring the level of refrigerant in the system. A loss of refrigerant will make the system very inefficient and even stop it from operating.
posted by JoeZydeco at 2:36 PM on February 10 [2 favorites]