Ductless minisplit – completed Manual J
We purchased a 2 story passive solar designed house in southern Ontario that was referred to as a 1980s eco house design similar to this (https://www.greenbuildingadvisor.com/homes/passive-solar-home-1980s). Slab on grade, southern exposure, minimal northern windows. Wall design 2×6 framed, vapour barrier, 2×2 horizontal strapping for all electrical runs and then drywall. Minimal holes in the polyethelyne (a couple holes to run exterior wires, kichen exhaust, no bathroom exhaust). No holes in second floor ceiling, all lights are on walls and attic access is via outside gable hatch. Currently has electric baseboard but we only used the woodstove to heat the house this year going through about 2.5 cords of wood (which means we didn’t leave the house for extended periods).
We have lived in it for about a year to see how the house functions and plan a few renovations, mostly update a few things for our comfort level. As much as I like the wood stove and the heat is provides we are planning on installing ductless heat pumps. This will free up some of my time for my young family and allow us to use a more efficient electrical when we cant feed the stove.
So first thing first, i contracted out a manual J by a third party company as recommended by the fine folk here.
-8F outside design temp, 72 inside design temp
82F outside design temp, 75 inside design temp
Our load after adding attic insulation and new windows which is planned work
32000btu/hr heat, 13900 latent cooling 11000 sensible
Main floor – 18500 heat, 5500 cool, 2nd floor 13700 heat, 8400 cool.
This numbers may be adjusted, we are having a blower door performed next week which we can pass on results to our hvac designer (currently assumed 3.57 ACH).
I want to plan on 2 single zone heat pumps, one main floor and one upper, please see attachment for locations. I understand that there may be temperature variations in the rooms by a couple of degrees when doors are shut. The models I am looking at are
Fujitsu XLTH 12RLS3HY
Advertised to provide 12000 btu cooling (3100-13600) and 16000 btu heating (3100-22100)
I am looking for opinions on if this will provide enough heat or if i should move one of the units up one level to slightly oversize to 15RLS3Y and 18000 btu. I will be asking this question to my hvac designer but i am always open to a 2nd (and 3rd, 4th 5th) opinion.
Thanks for any insight
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