Derek ColeGM, Simmons One Hour Heating & Air · AI HVAC Answers

My Upstairs is Always Hotter Than Downstairs in Summer | HVAC Solution

27 Jul 2022 · 2 min

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2:27

In this video Derek Cole explains why the upstairs of a home is often hotter than the downstairs during summer. He attributes the temperature difference to basic physics—heat rises—and to the greater heat load in the attic compared to a crawlspace, as well as differences in window exposure. He points out that many homes have a single thermostat located downstairs, which forces a single HVAC unit to over‑cool the lower level in order to keep the upper level comfortable. Drawing from personal experience, he describes how this leads to uncomfortable conditions downstairs. Cole recommends solving the issue by converting the existing single‑unit system into a two‑zone setup, with separate thermostats for upstairs and downstairs, rather than installing a second HVAC unit. He notes that zoning is straightforward if the house already has a duct chase that can serve both zones, but acknowledges that homes lacking appropriate ductwork may face challenges. Overall, the video emphasizes zoning as a cost‑effective, practical solution to the common problem of uneven temperature distribution in two‑story homes.

Chapters

The problem with one unit covering both is that you have different demands upstairs than you have downstairs. So when you look at a house and think about it, heat rises obviously, right? So when heat rises upstairs, typically will be warmer than downstairs, right? So chances are, I've seen this before, the thermostat is downstairs. You have a unit that runs the whole house up and down. So to get upstairs comfortable, you then have to make downstairs freezing. When I first got married, we lived in the apartment that was 2 stories but had 1 unit. So I mean, when you went downstairs at nighttime, it was like you better put on like a big coat and everything because it can happen. Because upstairs you have more of a load than you have downstairs. Downstairs, heat rises. You also have the attic upstairs, so you have these forces you're going against. You have the attic, you have windows, you have upstairs heat rises and downstairs, of course, cold air falls and you don't have an attic downstairs. And the crawl space is not that much of a heat load compared to an attic. So it's different demand. So how you solve that problem is either two units or what we've done quite a few times, which is zoning. You make downstairs one zone, you make upstairs one zone. It's very simple. If you have a unit that covers up and downstairs right now, you can very simply make it a 2-zone system. That way you have a thermostat downstairs, you have a thermostat upstairs. You can keep it that temperature you want, you keep it that temperature you want, and you can make it work that way. So the challenge with some houses is that there is not that duct chase in the house for the duct to be run to have one unit for the whole home.. But if you already have that, obviously that's available, but you just need to make it a zoning situation. I wouldn't get 2 units. I would just zone it upstairs, downstairs, and that will solve the problem. But until you do that, it is what it is. I mean, the thermostat downstairs, upstairs is warmer in the summertime. It's going to be, so you're just going to have to freeze it out downstairs and Get upstairs as comfortable as possible.