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Fans are very underrated. I've been heating 1700 sqft of living space using a 25k BTU mini split in Maine for 2 years now. The hot air is moved with some repur

Fans are very underrated. I've been heating 1700 sqft of living space using a 25k BTU mini split in Maine for 2 years now. The hot air is moved with some repurposed computer fans up high in a few doorways, and a return cold air fan , like your case, blowing the lower colder air back to the room with the mini split. The introduction of the fan moving the cold air into that room has a FAR larger impact on the house temp than just the fans moving the heat alone. (They obviously help as well but it's far more effective to move the cold air). As a geek side note, I also have a few "in wall" fans that direct into 6" vent work, and come out floor registers for the second floor. There are enabled or disabled via esphome temp sensors -- when a differential greater than X is noted, the fan(s) turn on, more rapidly evening the temps upstairs and downstairs. (To be fair, I also have an oil hot air furnace, and a wood stove, but the furnace has not been used for 2 winters, and the wood stove on the cold cold days in Jan/Feb when the heat pump isn't very happy)

smeej 2y ago
Can I hire you to figure out how to cool my space? It's only 625 sqft, and it's all one room except the bathroom, which accounts for the middle third of one side of the house (kitchen is on one side of it and bed area on the other, but they're not separated from the other half of the house by anything. The problem I have is that all my windows are narrow casement (crank out) windows, so the only AC I can use is a floor unit, with a plexi plug covering the rest of the window. They're too narrow for real window ACs. It's 14,000 BTU, ostensibly, and has a dual hose to avoid creating negative air pressure inside the house, but it can only really keep it 10-15° cooler inside than outside. That's fine until it's over 90°, which thankfully doesn't happen all that often. The AC has to be in the southeast corner, and there can only be one, because all the outlets near the windows are on the same circuit, and it's not able to power two. Oh, and the whole east wall is a giant double sliding glass door, which has a gorgeous view of the river, but gets hot first thing in the morning. I'm mostly kidding, but man, any suggestions for how to improve this would be great!
- BizarroLand 2y ago
  I had a similar issue in my old apartment. You might consider the use of a thermal battery. Cool the space at night (when it's cooler already) as much as possible. Then during the heat of the day, use thermal curtains to both block the heat out and to trap the cool in. On days where that is simply not enough, cross breeze is underrated. Get one of those magnetic mosquito door net things and set it up on your front door. Open the windows and the doors when it's too hot for the AC to help and get some air movement with a fan if necessary to push air from the shady side to the hot side.
  - smeej 2y ago
    At least I know I'm on the right track. I've been doing all those things! Fortunately cross breeze often comes in off the river, which is cooler, and I'm far enough north that it doesn't break 100° more than once or twice a year, if that, so I guess maybe this is as good as it gets.

smeej 2y ago

Can I hire you to figure out how to cool my space? It's only 625 sqft, and it's all one room except the bathroom, which accounts for the middle third of one side of the house (kitchen is on one side of it and bed area on the other, but they're not separated from the other half of the house by anything. The problem I have is that all my windows are narrow casement (crank out) windows, so the only AC I can use is a floor unit, with a plexi plug covering the rest of the window. They're too narrow for real window ACs. It's 14,000 BTU, ostensibly, and has a dual hose to avoid creating negative air pressure inside the house, but it can only really keep it 10-15° cooler inside than outside. That's fine until it's over 90°, which thankfully doesn't happen all that often. The AC has to be in the southeast corner, and there can only be one, because all the outlets near the windows are on the same circuit, and it's not able to power two. Oh, and the whole east wall is a giant double sliding glass door, which has a gorgeous view of the river, but gets hot first thing in the morning. I'm mostly kidding, but man, any suggestions for how to improve this would be great!

BizarroLand 2y ago
I had a similar issue in my old apartment. You might consider the use of a thermal battery. Cool the space at night (when it's cooler already) as much as possible. Then during the heat of the day, use thermal curtains to both block the heat out and to trap the cool in. On days where that is simply not enough, cross breeze is underrated. Get one of those magnetic mosquito door net things and set it up on your front door. Open the windows and the doors when it's too hot for the AC to help and get some air movement with a fan if necessary to push air from the shady side to the hot side.
- smeej 2y ago
  At least I know I'm on the right track. I've been doing all those things! Fortunately cross breeze often comes in off the river, which is cooler, and I'm far enough north that it doesn't break 100° more than once or twice a year, if that, so I guess maybe this is as good as it gets.