GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Heat with a minisplit in Ontario

joemcrae | Posted in Mechanicals on

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 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.

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. Expert Member

    A bit of a side issue - and I realize these are preliminary plans - but have you worked up any elevations for the house? The current plan, with its partial split level, is one I'd have trouble with in three dimensions.

  2. joemcrae | | #2

    Hi Malcolm,
    Here are some pictures of our house to give you a better feel for 3D. In the indoor picture you can see the stairway down to the living room and in the upper right, the stairway up to the master. The large windows on the addition face South.

  3. Expert Member

    My comment was due to my lazy skimming of your post. I assumed your "rough plans" were for a new house build. It looks like a really nice place. Sorry I don't have any useful advice for your question.

  4. GBA Editor
    Martin Holladay | | #4

    Q. "Do I need a minisplit head in an unfinished basement (spray foam envelope)?"

    A. No.

    Q. "Has anyone used the Senville heat pumps?"

    A. Sorry, I can't help you here. GBA readers?

  5. kenorakq | | #5

    I've not heard of senville..... but GREE also makes a ASHP that works to _30c .. I'm planning in installing p e in my p?ace in Kenora

  6. Expert Member
    Dana Dorsett | | #6

    Being able to operate at -30C isn't the same as having a specified output at -30C. Operating at 30C doesn't mean that the unit self manages defrost icing build up in the bottom pan of the outdoor unit. Without more information, put an asterisk next to that specification.

    Without the extended temperature capacity tables there's no telling guess how likely it is to deliver satisfactory results. To be able to sell it in the US market at a given nominal heating capacity, it only needs must be able to deliver that capacity at +17F (-8C), and doesn't tell you much about it's capacity at -20C or -25C, nor does it even tell you it's maximum capacity at +17F,which can be higher. The nominal heating capacity is the chosen modulation rate at which it's tested for HSPF efficiency, but it's max output @ +17F can be higher, and sometimes is, but not always.

    Mitsubishi FHxxNA units are designed to turn themselves off at about -30C, then restart at about -25C as it warms up, but the Fujitsu xxRLS3H units keep on going no matter how cold. Both have a specified output at -25C, and both have pan-heaters (optional with the FHxxNA) to keep them from self-destructing during extended cold weather use.

    I searched the internet in vain to find even the efficiency test submittal pages for Senville mini-splits, let alone engineering manuals with extended temperature capacity charts. The one installation manual & downloaded & skimmed through did not even mention defrost, let alone ice management, and had no heating capacity information.

  7. joemcrae | | #7

    Thanks Dana. I have done the same. I have actually asked Senville for this information and will post back if they provide anything.

    Today I found some reassuring anecdotal information of people in PEI that are very satisfied with their Senville units - This is crazy long thread (I'm just posting here in case people in the future are looking for more information. I hope this is OK.

  8. kenorakq | | #8

    Dana: thanks...point taken...I learn a lot here and just learned something new :)

    I contacted Gree Canada

    several weeks ago with a request for more information about the U-Crown series unit that clearly indicates that it to heat to -30c (their online data is like most advertising... incomplete... have a look at the home page and then the information provided about the U-Crown units) I have not heard back from them!

    I will contact them again with some more pointed questions.

  9. Expert Member
    Dana Dorsett | | #9

    The Gree Crown's submittal sheet has extended capacity tables attached, showing it's output at -22F (-30C). At 68F (20C) indoors and -30C outside the 1.5 tonner is good for a max capacity 15,510 BTU/hr, per the table.

    That's max capacity, not including defrost cycles, but assuming it's not total BS, that should give at least some confidence in using it at temperatures that low.

    The Crown series uses intelligent feedback on the defrost cycles, but I couldn't find mention of a pan heater to manage defrost ice build up in cold climates in the manual.

    That's not necessarily a big deal if you're willing to keep an eye on it and manually clear ice if the condensate drain freezes up in cold weather, but without an automatic pan heater you DO have check on it periodically if it hasn't warmed up to 0C for awhile.

    As I understand it, Mitsubishi will void the warranty for ice build up damage in climates as cold as yours if it was installed without the optional pan heater.

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |