631. Critical HVAC Sizing | #AskDerekCole Episode 108
28 Jan 2026 · 8 min
Solo episode by Derek Cole (Ask Derek Cole, ep.108) answering homeowner HVAC questions. Key advice: signs a system needs repair include complete failure, unusual noises (squealing), high energy bills, and poor dehumidification; recommended preventive maintenance is twice yearly (every six months). On sizing, Cole recommends a heat loss/heat gain calculation for every home, warns against undersizing (insufficient comfort) and oversizing (short cycling, increased wear), and cautions about installing equipment bought online because of warranty and registration issues. Mentions company practice of 10-year parts & labor warranty for new installs and North Carolina requirement to file heat loss/gain for system changes.
Chapters
Hey, on this episode we're talking about how do I know if my H Vac system needs repair? And what size system do I need? You ask your comfort and energy questions and they get answered. This is the Ask Derrick Cole Show. Hey, and welcome to episode 108 of the Ask Derek Cole show answering our home and energy questions. Thank you so much for the support of episode 107. It was great to be back. It's great to be back. And we're going to start with the first question, which is how do I know if my H Vac system needs a repair or something is wrong? Number one, if your system is not working, that is a good sign it needs repair. A few things that you might not think about that could be a problem is high energy bills. If you hear kind of a funny noise, squealing or some kind of noise you haven't heard before, it could mean you're having problem. High energy bills. You get that bill every month. Of course, when it's really hot or really cold outside, that energy bill reflects that. But if you're having, you know, just regular weather or regular stuff that you're used to and the energy bill is higher than normal or even in the summer months or the winter months and that bill is higher than usual and it doesn't seem right, it's probably best to get a technician out there to see what's going on to check your system. We always talk about you should be having your system maintained twice a c. Twice a year, once in the fall, once in the spring is ideal. But every six months is the standard. Every six months, regardless of winter, fall, summer, spring, whenever it falls, every six months is what you want to do. You can catch a lot of things, not everything. You can help prevent a breakdown when it going into that hot summer or cold winter is something the manufacturer recommends. It's something we recommend. Your system is very similar to your car. Your car needs to be serviced. Your system needs to be serviced on a regular basis, just like your vehicle. You know, as a standard here, you may not know, but as a standard here we do all new installs with a 10 year parts and labor warranty. If I have a 10 year parts and warranty, then why do I need service? And we like to say it's kind of like say you have a Toyota, it's got a bumper to bumper 100,000 mile warranty. Bumper to bumper. Okay, you have engine problems. And then they pulled service records 50,000 miles into it. Hey, you've never, never had an oil change since you got the vehicle, is that engine failure going to be covered? Probably not. Because you do have responsibility to maintain your system. Just like you want to maintain your car. You want to change oil, you want to get the tires rotated, you want to get the radiator flushed. You have responsibility for your H Vac system. The same way, regardless of age, regardless of warranty, you should get that system serviced twice per year. That would help catch some problems. It won't prevent everything from going wrong because it is a machine, just like a car, it is going to fail unexpectedly. But you want to get taken care of and maintained the best you can. So if you think you're having a problem, first of all, if your system is not working, that's, you know, sign number one that we have problem. But if your system is working, but you hear like a squealing noise or any kind of noise, if you have high energy bills, if it seems like it's not dehumidified, if it seems too humid in the house, it's not dehumidifying, that's a sign there could be a deeper problem. So have that checked out and have looked at by a professional. Number two, what size system should I need? Very popular question. Every home is different. I hate to give kind of a non answer, but every home is different. We do a loading analysis on every single home. We go to to change the equipment out. We measure the home to make sure that system is rightly sized for that space. So what does that mean? Well, your home has insulation, has windows, the door orientation north, south, east, west, all that and the windows, north, south, east, west. All that is going to factor in to what your home needs to heat and cool the home properly. It's called a heat loss, heat gain calculation. It should be done on every home because even this past summer we've like every summer before, I've been doing it over 20 years. We rented a home that are not comfortable and it's usually an undersized unit or, or an oversized unit. You can have too much unit for your home and then you go back to that short cycling problem. Unit turns on and off quite a bit. It doesn't seem to last as long because the wear and tear is greater than a rightly sized system. So you won't always get a heat loss, heat gain done on your home. If the contractor you're using does not do that. That is a red flag. That is a red flag. The state of North Carolina requires every single system changed out. They have to have that heat loss, heat gain in the file to make sure that system is the right size. So people call in and say, can you give me a price on a 3 ton or a 4 ton or a 2 ton or hey, I can get a 3 ton online. Can you install it for me? That's a whole different bowl of wax. The quick answer is no, we can't because we're not supplying the equipment. Therefore we cannot warranty it. We don't know what kind of shape is in. We don't, we don't know what kind of situation is being in. If we buy the equipment and we buy the warranty and we buy the labor with that and we install it, then you can 100% back it up. But if you get something online, first of all, they won't let you register it. So you don't get the 10 years to warranty. You can't back it up because what are you doing? What are we doing? So you need to have the right system for your home. How to know it's the right size? If you've been home for 20 years, you've been comfortable, it's probably the right size. It's probably the right size. But still a heat loss, heat gain needs to happen for that to be failed. We're just going to check which is going to double check again. This is a 10, 12, 15 year decision. There's no reason to be in a hurry and not do what you should be doing and cross those T's and dot the I's to make sure you have the right equipment for your home. Anyway, that is episode 108 of the as Derrick Gole Show. It's good to be back. If you have any questions, be sure to hashtag them online or in the comments. Ask Derrick Cole and we'll get them on the show.
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