Heat with a minisplit in Ontario
I’m looking at replacing my HVAC system this year. I live near Peterborough Ontario. Currently my system is composed of a 60 year old oil boiler, a wood stove and portable AC units in bedrooms. I had previously asked a question https://www.greenbuildingadvisor.com/community/forum/mechanicals/98848/retrofit-hvac-installation-zone-6a about a boiler.
Some information from that post that is relevant here:
Using bills for oil from last year I calculated my heating load (@ -4F) to be 22000 BTU/h. Basement, addition and main home have been spray foamed. There is R50 in the attic.
I’ve now attached a rough floor plan for our house. The master bedroom and living room are split (1/2 floor up and below) from the original bungalow.
As I continue to research options for my home, I’ve become interested in the possibility of using minisplits. The operating costs during heating season of both systems are comparable. They are comparable for me because I currently don’t have a gas bill and my gas utility will charge $20 / month all year for my gas connection. This additional $240 balances the extra cost of heating with a minisplit.
In my first post I discussed the importance of IAQ for my wife, specifically keeping RH below 50% in the summer and shoulder seasons.
I would be grateful for your thoughts on my new plan:
1. Install a 4 head ~36000 BTU/h min Senville or similar Mitsubishi minisplit system. (One 9K BTU/h head in Master, Living, Hallway and Larger 2nd Bedroom)
2. Install Panasonic exhaust fans in bathroom with cycle switches for an exhaust only ventilation strategy.
3. Buy a portable dehumidifier for basement and main level for use in shoulder seasons.
4. Keep Oil Boiler for backup, while I collect data on system performance.
In the winter use all heads to heat house. Set thermostats according to use.
In the summer only use the hallway and master heads to cool the house (this way the system will be more appropriately sized, run longer and dehumidify adequately.
Questions I still have:
– Do I need a head in an unfinished basement (spray foam envelope)? Currently there is one radiator and the boiler in the basement. It’s OK if the temps are lower, in the basement we only use this space for storage.
– Has anyone used the Senville Heat Pumps? As far as I can tell they are the only units that advertise working at -30 C. We hit those temperatures maybe once a year. I’m leaning towards the Senville because I think I could have their system installed twice for the same cost as the Mitsubishi system. Hopefully I wouldn’t have to.
I like this system better than a boiler / ductless AC system because the costs will be lower, but more importantly, it will allow the master bedroom to be zoned (it has huge south facing windows and is always hot in the summer or cool in the winter when using central one zone systems). We do not have enough radiator output to run more than one zone with a mod con boiler.
Thanks again so much for your help.
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