It's heat retained from the day's sunshine.
Wait, what did you think I meant?
Hmm. Maybe that title was a bit misleading. Sorry about that.
At any rate, our bedroom is upstairs and the thermostat for the AC is downstairs. By morning, the upstairs is noticeably warmer than the downstairs. We had thought it was from our bodies, but I don't think that's the case any more. Dig this temperature chart from my Sensor Plus sensors.
Yeah, I know there are no axes or tick marks. Hey, this is a hobby blog, not a SciAm article. And if it had been a SciAm article, you can be sure I'd call you a racist transphobe by the time I was done, so be grateful for small things.
The chart covers a couple of days. At their farthest distance apart, the upstairs, which is the blue line, is about 5-6 degrees warmer. One sensor is upstairs and the other is downstairs.
The red circles show the times we crank the AC. The green circles indicate something different and typically happen around 0300. Why does the upstairs heat up around 0300 every day?
It's all about heat capacity. The AC isn't just cooling the air, it's cooling the structure of the house. By 0300, the downstairs walls have cooled to 68 degrees, our thermostat setting. From that point on, the air down there stays around 68 and there's no need for the AC.
Upstairs, we border the attic which has a substantially larger heat capacity than the downstairs walls. It's still warm from the day so our room heats up and the thermostat downstairs doesn't know it's happening.
The solution is actually quite simple. The HVAC pipe junction is in the attic. All we need to do is put a register in the attic and the AC will cool it down while it's cooling the house. By the time 0300 rolls around, the attic should be nice and cool like the rest of the house. Clever, no?
Also, you're a racist transphobe.
3 comments:
My first thought is you don't have enough insulation in the attic.
We have the opposite issue. The basement is substantially cooler. Especially in winter.
I have a box fan running all summer blowing air up the stairs. I also have a remote sensor for my Ecobee thermostat, that senses temperature and occupancy. So it can use that sensor as the source of truth for whether the heat or AC should run based on occupancy, time of day, etc.
The ultimate solution is to have smart duct work that only sends cooling where it is needed.
You are an evil swine. :-)
It sounds like you have a good argument for relocating the thermostat upstairs instead of downstairs.
It makes sense for a heating system to have the thermostat downstairs, because as you heat the downstairs the lower-density warmed air tends to rise upstairs.
But for a cooling system, it will work the other way around. Basically, you want the thermostat to be in the place that gets cooled last, so that everywhere else in the house is cooled off by the time the thermostat sees it.
Another approach you might try, is a ventilating fan in the attic that only turns on when it is cooler outside than inside. When you say 0300, you mean 3 in the morning, right? It looks like San Diego cools off pretty nicely during the night, so if your attic ventilation fan either turns on when the outdoor temperature drops below 70, or a couple of hours after sunset, it should vent out all that attic air that got heated up all day.
We actually get along pretty well without an air conditioner at all, just by taking advantage of the cool air at night. Granted it is a lot hotter in San Diego, but I think you could take a lot of load off of your air conditioner just by taking advantage of cool air that becomes available.
Oh, and white shingles! White shingles keep your attic a lot cooler than dark-colored ones.
I haven't spent a lot of time in Houghton, but it doesn't get too hot for very long in July/August.
Move in day at the dorms is probably the hottest day up there. With 8-9 people in a room designed for 2 but now has 3. With the freshmen moving in, Moms' fussing over the moving in, and Dad's rolling their eyes. That's my memory. But yeah, there are a few days up there where AC would be a welcome addition. Plenty of ways around that as you say.
My days in San Diego were always within a few miles of the beach, A/C was never a concern. I am ashamed to say I did use the electric ceiling heat in my first apartment down in Ocean Beach a few times in "winter". I definitely remember driving with the top down in my car on Christmas Eve that year.
However, further inland, it gets hot quick. I seem to remember my route riding my bike out and around Jack Murphy stadium, the temperature could raise 10+ degrees from the beach out to there. What is that 10 miles?
I am under the impression the Catican Compound is out further still. Practically Arizona by my 22 year old standard.
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