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New build - mini split HVAC?

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  • Aug 9th, 2018 8:54 am
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Sep 9, 2007
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Toronto

New build - mini split HVAC?

Next few weeks I will be in the process of getting quotes for mini-split HVAC system. Curious, if anyone has gone ductless and if so, how is that working out?

The house will be a a two story build: main floor with an office and a living/dining/kitchen, and a 2nd floor with 4 bedrooms and 4 bathrooms. We will be insulating the foundation, the attic and spray foam the cavities. There will be two fireplaces(master bedroom and living room) that will be actively utilized during winter. All bathrooms will have heated floors and towel warmers.

By looking at the drawings It looks like 8 head mini-split should be sufficient to cover the whole area: 1 head x each bedroom(4), 1 head in the upper hall(cooling lower hall too), 1 cassette in the dining/living/kitchen area, 1 head in the office and 1 cassette in the basement.

Few areas of concern are:
Heating: Given that last few years have been somewhat cold in Toronto, how good are heat pumps w/mini-slits at keeping the place warm? I've been reading that heat pumps may not be a way to go if outside temperatures are below -15c.
AC/cooling: What would be the best way to cool the bathrooms? Besides proper ventilation, cold air from the heads wont have direct way into the bathrooms so I am a bit concerned with not having a "sauna" during +35c days. I think an air handler or a ducted mini split zone may be a solution for the smaller spaces?
Hydro: how much electricity would such system consume comparing to conventional forced air HVAC systems?

We'll do a heat load calculation before going any further but I just wanted to get some head start and some input.
Last edited by LembergMX on Aug 9th, 2018 1:21 am, edited 2 times in total.
7 replies
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Sep 5, 2009
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My ductless unit is running right now :-)

I'm current in a bungalow and we have 2 units that cool the whole main floor. Even rooms that are enclosed and don't have a unit get cooled so they work pretty well. Your bathrooms will be nice and cool.

I moved from a forced air system in my last house and find the electricity costs to be the same.
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[OP]
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Sep 9, 2007
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dgnr8 wrote: My ductless unit is running right now :-)

I'm current in a bungalow and we have 2 units that cool the whole main floor. Even rooms that are enclosed and don't have a unit get cooled so they work pretty well. Your bathrooms will be nice and cool.

I moved from a forced air system in my last house and find the electricity costs to be the same.
How about heating, during the last winter?
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koleso wrote: How about heating, during the last winter?
I have radiators for that.
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Quite a few spec (as in speculative?) build houses in the mildest part of the country are being built with mini-splits.
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Apr 14, 2007
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There are mini splits that can hear even at -30. Fujitsu makes a model that beats at those temps
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This is bizarre to me, a new build...in Mississauga and without ductwork. Are you on gas? What's the rationale for going this route?

Yes, these units can run down to about -20 but there will be days that supplemental heat will be needed. Typically I've seen baseboards used. I think that other poster had an existing rad setup.

In the summer absolutely the upstairs unducted rooms with windows that you might keep the doors closed will be cookers. 8 head units to maintain as the filters need cleaning regularly. The head units while you sorta get used to looking at them are rather unsightly...personal opinion. Right now you created a Mish mash of heating and cooling system neither looking very efficient when looking at install costs. Even with the vent and louver settings these are drafty and directional ...if you like drafty cool or hot air then it's great!

Ductless also don't circulate air from outside...it's pretty much in code to have an HRV and a forced air system can piggyback on some of the ductwork...are planning on doing an HRV? With airtight homes fresh air circulation is crucial or can be prone to mold/must.
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Nov 16, 2011
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HAMILTON
Ductless are really interesting and a somewhat viable alternative but in a new build, you should also be considering future resale. No ducts mean that any future owner that wanted forced air, would have to install ducts throughout the house, etc which could be a real deal breaker for future sales.

I think that ductless has their time and place, but not as primary heat/cooling but secondary heat/cooling in many areas of Canada that can suffer significant temperature fluctations.

Personally, I have found that the best place for a furnace is in the middle of a house ( albeit may not be the choice of many ) but this reduces the hot/cold areas in homes as less ducting to rooms.

Best of luck on your heating choice and would love to know how it works out cost wise, heat wise and resale wise.

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