I have a house with four heating zones, three of which are pertinent to this question. A standard summer day might look like this:
- Top floor - 23c-24c (slightly too warm, AC on most of the time on warm day)
- Main floor - 22c (just fine, AC on sometimes)
- Basement - 18c (slightly too cool, also too humid)
Note that my home is in southern Ontario.
I'm thinking I should run the furnace fan 24/7 in the summer (and perhaps winter) as it would move warm air from upstairs into the basement and move cool air from the basement into the top floor. It may also help regular humidity in the basement, though I'm not sure.
A quick Google Search suggests running the fan all the time might cost me 45$ a month or something. This is not a negligible sum, but if it prevents the AC from running to cool the top floor it might be worth it.
Also of note is that I have a large wood and efficient fireplace on the main floor. In the winter this will heat the main floor well, but not other floors. Circulation could be nice here.
Does it make financial sense to run my furnace fan 24/7? Or perhaps 50% of the time? Either way, should it run as fast as it can go (assuming I tolerate the noise)?