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Inline fan for comfort issue

GSFish | Posted in General Questions on

Hey Folks,

My house in North Jersey has a 1 pipe steam system with an oil fired Beast in the Basement….1950’s era, ~130k btuh.

Last summer, I installed Daikin mini-split heat pumps (no electric strips), mostly to address the lack of cooling, but I was pleasantly surprised with the heating capabilities.  I was good with the heat pumps until ~28F OAT in my open living space on the first floor (where I have a single 2 ton head), and good with the heat pumps all winter in the bedrooms. 

I did some load calculations that revealed I needed to makeup about 30k btuh at design day conditions to hold the first floor at 68F.  Instead of firing that massive boiler–and for the ambiance– I’ve decided to install a gas fireplace on the first floor.  Moving forward into this heating season, I intend to try and run the whole house on a combination of heat pumps + gas fireplace.  

My only issue: i have a far flung laundry room in a converted garage that is nearly impossible to heat, even with the existing radiator.  I’m certainly not going to fire the boiler just for that space.

I had an epiphany the other day: I can cut a register into the floor, drop a return there, make a short duct run in the basement below, and use an in-line fan ( send ~200 CFM of warm air from next to the fireplace over to this laundry room.

Anybody ever do this before?  Am I crazy to think this will work?  I feel like a little fan that can circulate locally heated air to an isolated cold spot could be a decent bet…and something I can do for less than $200.

Any thoughts?  Thanks, all!


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  1. Expert Member
    BILL WICHERS | | #1

    Yes, you can do that. It won’t be as effective as a “real” hot air register since you’ll be moving air that is approximately room temperature so less total thermal energy delivered with the same amount of airflow in CFM. If you run the fan continuously it should help with that distant room though.


  2. Expert Member
    Dana Dorsett | | #2

    Have you run a heat load calculation on that laundry room?

    Is the primary goal freeze protection or does it have to be sorta-comfortable in there?

    Do the math:

    Assuming you only need it to stay above 50F and you're pulling 200 cfm (=12,000 cubic feet per hour) of 70F air with the fan, that's a temperature difference of 20F. The amount of heat you're moving is then:

    20F x 0.018 BTU/cubic foot x 12,000 cubic feet/hr= 4320 BTU/hr (not counting duct losses, etc.)

    Would that about cover it?

    1. GSFish | | #3

      Freeze protection at zero degrees outside is primary concern. A comfy wife is, in this instance, the secondary concern. Perhaps I have those priorities backwards??

      But thanks for backing into that load for's reaffirming to that this should work. 4300 BTU/hr should cover it. Strong preference is to use a gas generated BTU for that space instead of putting a strip of electric baseboard in there.


  3. gusfhb | | #4

    Might a small electric wall heater not be easier?

    While it galls to use resistance heat, the cost is so low that it will be difficult to compete even in the moderately long term.

    I used to have a small bath that had no direct heat, added a little wall heater right in front of the pot. On really cold days, or days you felt really cold, just reach forward and turn up the knob.

    Might also be more wife pleasing than a stream of coolish air

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