I recently purchased a house originally built in 1953 as a ranch style house, that was transformed in 2009 to a modern style house with a brand new second floor addition and a overhaul of the original main floor. It was built with eco-friendly material, double-insulated exterior walls (upstairs and main floor) and all the windows added/replaced thermal gas filled, metal frame windows. The upstairs AC unit is a High Efficiency Heat Pump, the main floor and basement are covered by a older, yet still high efficient (PVC piping) standard AC / Furnace (Gas). The basement, which is a walkout basement is always cool. Picture of Front of House
(North Side)Picture of Back of House
I work from home, my office is upstairs, so I am here all the time, but my main floor I run a lot warmer during the day because it doesn't cool well and would be wasting money since most of the time I am upstairs except when kids come home around 3-4pm each day. I run a Nest thermostat on both units which I love, and helps me see how much my AC is running and to formulate ways to run my AC smarter.Main Floor / Basement AC Replacement and Optimizing
My AC guy who I've used for years at various places I've lived said my main floor AC unit is high efficient (PVC piping) but is older and since the outside unit is leaking some, it will probably need to be replaced/upgraded to the new RFC standards, since replacing what it uses now is costly since price jumped up now that it will be discontinued.
The main floor is always hot, the AC runs a lot to keep cool and I've given up trying to keep it at the temps I keep it upstairs otherwise it would run significantly more or all the time, so I set it around 78. even when it's only 85 or 90 out, but of course has issues when its 100 out, which has been our weather last summer and this summer as well. The upstairs unit can drop the temp from 83 degrees to 78 in about 15 minutes when the outside temp is 95, but then it slows down as it cools more, with around 30 minutes total to get to 76 and an hour to get to 74 (from 83). This is as the outside temp is rising and getting closer to 97 at this point. I am very pleased with the upstairs unit. It cools, it shuts off. It cools, it shuts off. The main floor, takes much longer to cool, and the AC guy said the unit is not as large as the upper floor unit. View my Upstairs Nest Energy ReportView my Main Floor Nest Energy Report
Unfortunately, I have been screwing around with my Nest and I removed the schedule and so it came back to bite me. I've also been hesitant to use the "away" feature since I didn't want the house temp to rise too much since it seems when I allow it do that, it runs longer that day because it has to bring down a higher temp. But it might be in my head.
If I replace the main floor unit with one with more power, will I gain anything considering the return air for the main floor is located down at floor level, along with the regular air vents. Seems like to me, the return air should be higher up by the ceiling, to suck in the hot air. I realize in the winter, this would need to be opposite, so maybe I'm clueless.
I have closed all my air vents in my basement, I don't see any return air vents in basement.
My AC guy said that with electricity going up, when it comes winter, I will have different issues. My upstairs Heat Pump is all electric, even emergency heating. He said I should avoid using it for when temp drops below 35 or so and allow my main floor / basement unit to heat house which is gas combined with main floor and upstairs in-wall gas fireplaces (which seem to dish out a lot of heat, I was surprised).
The main floor is open to the upstairs through a large open stairway on SW side of house, the ability of the upstairs to cool fast, seems to have no side effect to the main floor temp.
I don't want to replace it with a bigger unit for the sake of a bigger unit. I want it to run with the apparent quality of my upper floor AC unit runs and maybe it really is just a size issue. So, how would I best figure out how the ducts should be setup on the main floor and basement to best maintain the air temp on those levels? In theory, I would think, that having less heat on the main floor would lesson the amount of heat rising upstairs, thus allowing that unit to run less.
How do I best tackle all this?Sorry for the essay, but I wanted to cover everything.