I wanted to see if I could warm my utility room with some of the heat from my upstairs using my forced hot air furnace fan. The best result I could achieve was by opening only the lowest/coldest return duct located in the basement and blowing that air up through the registers to the floor above into the room where my stove is located.
In the small basement utility room I was able to get an 11 degree increase from 47 degrees to 58 degrees (although the room upstairs was almost 80 degrees at that time).
The heat pump water heater would benefit from the warmer air although until I compare electric bills it's difficult to tell how much it would offset the energy used by the furnace motor.
By running the fan I am filtering the air.
There was little to no cost to set up as I already have forced hot air system in place.
The cold draft around basement stairs disappeared.
I can use the "cool" program on my thermostat to turn on/off the furnace fan motor if the living room gets too warm.
During the hotter summer months I should be able to bring up some air for a short period of time(s) into my bedroom to assist in cooling.
The temperature in the basement room dropped quickly after furnace fan was turned off.
The time it took for the room to gain the full 11 degree rise (appr 45 mins).
Electricity involved running furnace motor.
The room was small, probably only 250 sq ft.
Noise from the furnace motor and wear/tear on the motor.
At some point I will be insulating that basement area and will try again. Except for adding insulation, any further testing will require no additional work or cost on my part. Although I can program my thermostat to turn on when the room upstairs becomes too warm there are newer thermostats which have a "circulation" mode that cycles the blower motor "on" for 30%-35% of the time. If the room retains some of the temps after insulating I will try to manually turn and/off the fan for this amount of time to see the results and determine if it's worth purchasing a newer thermostat.
I'm not sure if recirculating the would be helpful or harmful in redistributing CO2. Also, blowing up air from an unfinished room is probably not a good idea for homes with higher levels of radon.
With the current set up the biggest advantage I could see was cooling off the upstairs which can be done more effectively and efficiently by just opening a window. Until I insulate that room I will not be running the furnace fan. At the very least my heat pump water heater should benefit from the added insulation.