Derek Cole shows how to fix uneven temperatures between floors without buying a second HVAC unit. Install separate thermostats and zoning controls to direct airflow to each floor independently. You need adequate ductwork and a duct chase, but proper zoning lets each floor maintain its own temperature.
Chapters
If you have a unit that covers up and downstairs right now, you can very simply make it a two-zone system. 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 they 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.