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Installing minisplit: Ssould we decommission gas forced air furnace?

user-7000426 | Posted in Energy Efficiency and Durability on

We are building 750 sf extension on our house, which is currently 1200 sf (not including the basement). Both the house and extension are 2 stories. We are in Portland OR
We currently plan to put in a minisplit for both floors of the extension (kitchen and main bed), and one of the existing bedrooms.
So should we bite the bullet and get rid of the gas forced air furnace, which is about 98% efficient? We would have to replace the vents in the living room (12×25), the front hall (8×8), the study (10×10).
We also have a cadet heater that we might re-commission in the upstairs hallway. And another cadet heater in the front bedroom.
The furthest point from the minisplit outside unit would be the front bedroom, about 25 feet away and up one floor.
Is a minisplit considered green (I’m obviously on the wrong site if it isn’t).
Are the cadet heaters inefficient?
So I think my question boils down to this. Should we:
a) keep existing furnace and cadet heaters and just add minisplit in new bits
b) replace the whole shebang with the minisplit?
PS We are more interested in the efficiency, only a bit about the money unless our ROI in total replacement would be horribly low.

Thanks
Catherine

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Replies

  1. user-1072251 | | #1

    I've been going the same process. My goal was to head toward a net zero home, so I've upgraded windows (more to do) added insulation (ditto) and installed three minisplits in my old 2500 SF home. Then I installed my solar panels and stopped using the oil furnace and gas boiler which heats a separate room. After one winter, we ripped out the oil furnace, broke it up and took it to the dump; one of my happiest days in all the years I've been here. Now, four years later, I'm ripping out the gas furnace. The house is vastly more comfortable than it has ever been, all year. So my recommendation is to install the miniplits and keep the gas heater(s) for a year or two until you know you won't need it. The minisplits are less expensive to run and far more useful, since they'll do cooling and drying in addition to heating. Upgrading the house is a critical part of this so the heat is used more efficiently.
    As far as the cadet heaters, if they are electric, you might want to leave them, just in case. You'll know in a few years if they wil ever come in handy and if you're never using them, take them out.

    1. user-7000426 | | #2

      thanks for all the info and advice

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