Plan for ducting cold air and heat through fireplace

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New Member
Nov 9, 2021
Southeast US
I have a Caliber NXT 36 that I am in love with, in my 1000 sq ft home that is shaped like a square with 4 equally sized rooms. If you're looking at it from above, quadrant 3 of the square has the fireplace with an open doorway leading into quadrant 2 that is the kitchen, the kitchen has an open doorway that leads into quadrant 1, and quadrant 1 has an open doorway that leads into quadrant 4, the bedroom.

The Caliber NXT can burn between 20k to 40k BTU and has two unused heat duct holes for spreading heat. My house also has a bunch of unused floor registers from an old HVAC system I ripped out and replaced with mini splits.

I'm thinking of using a 6 inch duct around 10 ft long and an inline fan around 150-250 cfm to blow cold air from a floor register in quadrant 2 into quadrant 4 the fireplace room. I'm hoping this would be enough to get the fireplace heat into the other half of the house, quadrants 1 and 4.

Cold air is dense and heavier than warm air and I've heard floor registers are best used for managing cold air so this is my plan. Would this be enough or would I also need to duct in heat from the fireplace. I've heard this is less efficient and the ducts would be going about 10 to 15 ft through a hardly conditioned crawlspace or attic.

Would you prioritize moving cold air or moving warm air, and what would be your plan? None of the doorways have doors, I'm just trying to even out heat in all the rooms. 9 ft ceilings with small doorways, even with ceiling fans going in every room I can feel the hot air getting trapped in the ceilings of the fireplace room and kitchen.