Sorry, it’s going to be another one of those mini split questions.
2 story house in zone 6, SW Ontario, heating demand 12kBTU at 0F.
Currently have in floor hydronic, fed by electric DHW tank. Was led to believe by the crazy builder that the heating demand is so low that it doesn’t make sense to have a heat pump. This was a bit of a dubious claim to begin with, but coupled with the fact that actual heating energy has been at least double what was predicted, now it’s time to look at heating alternatives.
Part of me wants to salvage the in floor heating, adding either a Chiltrix or SanCo2. The Chiltrix just looks too expensive (conservatively C$13,000-16,000 for the outdoor unit, control, tank, two fan coils for cooling). For way less than half of that I can get a mini split. The SanCo2 is a little more reasonable, but still significantly more than a mini split and it provides no cooling. There’s also a rebate for air-air heat pumps, not for air-water.
Based on energy modelling I did at the tail end of the winter, it seems like 90% of the heat going into the house is going in on the main floor. So for heating purposes, it would probably make the most sense to just have a single 12kBTU zone on the main floor. The main floor is much more suited to single point heating as well, being an open concept. However, if I’m going to have a heat pump, I would want to have some cooling in the summer as well. Would cooling just the main floor help the upstairs much, or would it result in a huge temperature difference between the floors? Not really needing a lot of cooling, just dropping the temp 4 degrees F during the warmest 3 weeks of the year would be fine.
If I want a 2 zone system, is it acceptable to have the capacity of the 2 interior heads to exceed the outdoor unit, with the intention being that one be shut off in the heating season, and the demand will be lower in the cooling season? Like if I got a 12kBTU outdoor unit, a 12kBTU indoor unit for the main floor and a 6kBTU unit for the second floor?
If I went with just a single zone and found out it was a mistake, is it possible to add a second zone later on?