Derek Cole explains comfort sizing for HVAC systems: calculating the right BTU capacity based on your home's square footage, windows, and orientation. Proper sizing, installation, and duct work cut energy waste. Choosing a licensed contractor with permits and inspections matters more than buying the biggest unit.
Chapters
If you are considering replacing your heating and air at home, or if it's something you haven't even thought about, either way, when it comes down to replacing or heating and air, your system should be comfort sized for your needs. So what is comfort sizing? Well, it's a term we use around here, but really, anytime a contractor or anyone replaces the heating and air in your home, a load analysis must be done. Heat loss, heat gain, something called that basically is measuring your home, orientating your home. Where is your front door at? Where is your front door in relation to north, south, east, west? And that's going to affect the walls, the windows of your space to come up with the loaded analysis. So when they go out to your home, when someone goes out to your home, they should measure your square footage, measure your square footage of the home, of the space, get the orientation, get the sizes of the windows, get the sizes of the doors and measure that. Put it into a formula sheet or computer program, or you could do it by hand with the sheet and calculate how many BTUs, British thermal units BTUs your home is going to use. So a BTU is 12,000 equals 1 ton. So when you talk about air conditioning, you talk about tons of air conditioning. So you've heard people say, you know, I have a 2 ton or a 3 ton or 4 ton. What does that really mean? Well, that means the kind of BTUs it outputs. So a 4 ton would be 12,000 times 4,48,000 BTUs of cooling. So what? 40,000 BTUs of cooling isn't the, the actual cooling you're going to get out of the system because again, it's not, it's not 100% efficient. So it's not going to give you 40,000 in the house because you're going to lose, you're going to lose air through the duct system, through the ductwork, and that's, that's going to happen. And actually the warmer it gets outside, the less efficient the cooling gets. When you have an air to air system or something like a traditional heat pump or air conditioner, when you have a traditional, what's called air to air system, it gets less efficient the warmer it gets outside. So I think we're sized here for 95 degrees a 95 degree day. Well, there's some times where it gets to be a hundred degrees. It's not that often, it's not the average, it's not the normal. But once it gets to, you know, 98 or 100 degrees the unit is not going to keep up with the demand because it loses the efficiency and you're sizing the system off of what's normal. A 95 degree day is the normal. A 20 degree day in the winter time is normal. Sometimes it gets below 20. Therefore your heat pump has trouble keeping up then as well because it's below 20 degrees. So that's outsized here in southeastern North Carolina. 95 degrees in the summer, 20 degrees in the winter. But curvizing your system is more than just doing a load, it seem. What do you want? What are your habits? Do you like your house to be a little cooler in the, in, in the summertime? Do you need a two stage system? Do you need a variable speed system? Do you need a. What do you need? You know, is your home going to give you what you need? So comfort sizing is, that's one piece of comfort sizing. But it's not the only piece. But that is the main piece. A load analysis should be done on your space every single time. And you might be saying, hey, well Derek, you know, the home's 25 years old. This is the first time we're replacing the unit. I shouldn't need a different size unit. Well, maybe you shouldn't, but we should check, right? I mean, probably in 25 years you probably upgraded a door or a window or add the insulation or even added a room. Right. All these factors come into play with how, what sizing you need and how efficient you want to be. Because they have different tiers of efficiency. In 20, 23, they come up with Seer 2. What is Seer 2? Well, as driven in Seer, which is what they've traditionally been, Seer 2 is more efficient and different standards than what this SEER rating was. So all these factors come into play. It's just, it's just not a box. It's not like a refrigerator. It's not a box you plug in and you're done with it. The heating air system is not complete. It is a box. It is the equipment. And yes, all the equipment is pretty similar. You know, you have Trane, Goodman, Carrier, Ruud. Yeah, all these brands, but it's pretty much all the same stuff. There's only a handful of people who make compressors, who make control boards, who make reversing valves, things like that, make heat exchangers. I mean, there's not that many people and there's only a few brands that make all the brands. So if you look at carriages, that or look Goodman, let's look Goodman you look Goodman, you got, they're owned by Daikin. They make Daikin, they make Amana, they make Goodman. They make something called Distinction, which is another lower level line. So that's one brand. I mean, that one company makes what, four brands right off the bat? So there's not much difference. The difference is the box when it's installed. It's not, again, it's not an appliance. It's not something you go to Best Buy and pick it out and plug it in and be done with it. It is a incomplete, unfinished product. It's not something you can buy on ebay or Amazon or online and say, hey, can you hook it up? It's not the same thing. It needs to be done by a professional. Because the most important day in the life of a new system is the deus installed. The deus installed will tell you if that unit is going to last or not going to last. Do the given extended warranty with it outside of what the manufacturer does or don't they? I've been to quite a few homes as I had, for example, I'll get really technical here, but customers complaining. And we went to the home and another company installed the unit. It was a 14 unit and it had like a 5, 8 size line set for the upstairs, going upstairs, going up the wall to that system. Okay, so that unit was doomed from day one. So if you look back here in my line set chart, 4 ton went upstairs. So it's probably about 50ft. At minimum. I would probably do a 7, 8, 7 8. I mean inch and eighth. You can be perfect at 7, 8. You'll have a little bit of loss. But how do you size that line set which carries the refrigerant, which carries, that carries the blood? Basically. If the unit is your body, the refrigerant is the blood. The lancet, when it's a split unit, the lancet is the veins and arteries going to the unit. So if you have trouble getting the blood to where it needs to go, the system is going to have problems. Right? So that system, even though was a branded unit, it was a highly respected brand. The way it was installed, it was never going to operate efficiently and correctly. So again, it's an unfinished product. So comfort sizing, what we call it, is very critical because you have to understand the science of what you're doing and you have to do it correctly and by the manufacturer's instructions. Goodman, Goodman is a good brand. It's gotten a bad rap over the years because they sell to everyone. Anyone can buy Goodman that has a contracting license. So the standards of quality have really been compromised. And they started putting what's called a filter in the outside unit because people were not putting these in for units. And the filter dryer is very important. It goes on the refrigerator side and it filters out the bad things in the refrigerant. So that was not being done. So they had to install that into the units to, to help solve this problem. So when you buy a new system, make sure it's comfort sized. Make sure the contractor is doing the heat loss, heat gain analysis. Make sure they're already in a third party pulling the permit, getting inspection, and getting a kind of third set of eyes to look at what they've done to make sure it's good. Because choosing the right size system, but, but choosing the right contractor to install that system properly makes all the difference. Makes all the difference. So you want a, a company, company that's been around for a while. A company with a good reputation and someone you trust will be there when things go wrong. Because it is a machine, it will break. It's not a matter of if, it's a matter of when. So when it happens, who will be there to make sure you, the homeowner are taken care of? So all that goes into replacing your system and all that goes into comfort sizing.
