I have my office and rack in the basement where I work out of during the week. In the early spring and late fall when there isn't much cooling it would get rather warm to be comfortable (80F-82F).
A few weeks ago I realized that I have a cold air return duct in the ceiling so I cut an 8"x10" hole in it and left the furnace fan on 24/7 hoping that would help...it didn't really.
Last week I decided to hang an ~8" fan 3" below the hole I cut into the cold air return to see what would happen if I forced air into the duct...it didn't do much.
Last Thursday I remembered something from my volunteer firefighter days about how to set up a fan to ventilate a room through a window/door and how it was important to have the wind cover the entire opening. This led me to put a 12" fan in place of the 8" fan at 9PM.
Fast forward about an hour and my office was now 76F. The next morning it was 72F and it has stayed at 72F-73F ever since then.
The side benefit is that I'm able to provide a bunch of supplemental heat to the upstairs meaning that rather than my heat pump running 16hr+ per day with the electric strips kicking on periodically overnight during the <15F weather we've been having the heat pump has been running for 8hrs per day and the electric backup strips haven't needed to kick on at all.
I'm curious how it works for cooling next summer when I won't be able to run the furnace fan 24/7 since that'd just dump humidity back into the house so we'll see how that goes.
I'm still pretty happy with the results at the moment.
If you did nothing, the waste heat would heat the basement, rise up into and through the floor, and heat your house anyway.
Not in my experience over the last couple of winters. The office just stays at 80F or more while the rest of the basement is 70F even with a fan blowing from the office out into the main room in the basement.
Heat moves along its gradient.
I don’t know what to say other than I’ve tried it and it doesn’t work. I thought it would but it doesn’t.