Ductless minisplit selection, sourcing and positioning in a small high-performance home
I need to finalise the details on a heat pump for our 980sq ft high(er) performance home in zone 4C. The air sealing goal is <1 ACh, insulation will be slightly above code with 1 or 2 inches of exterior insulation, R26ish walls, R50 roof, R16 sub slab, triple pane windows. Heating loads came out a less than 1GJ annually, cooling 2.2GJ on our energy modelling. Sourcing a good contractor is proving hard due to our remote location and suggestions so far are leaving me uncomfortable with their expertise.
I have a few questions.
-Right now I’m looking at the Fujitsu 9RLS3. What’s the differences between the 9RLS3H?
-What other units are worth considering?
-Are there any online suppliers in Canada like ecomfort or recommended distributors where I could either buy the unit or use to figure out how much contractors are charging me?
-I’m unsure how many heads to use and where to locate them. I’m thinking about one in each bedroom, with the one in the master facing the door to the kitchen. We want to be able to keep bedrooms cool in summer. Part of my indecision is that I don’t have a good reference having not lived in any house like this. Will the bedrooms get warm enough they need cooling given the building components and overhangs? Would one central head in the living room be sufficient instead?
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Bump.
Where specifically are you located? Is Canadian climate zone 4C the same as US DOE climate zone 4c? If so, you must be on the coast somewhere.
With a house that size and a moderate climate, a single head right in the middle of the house is probably your best bet. Or, on the exterior living room wall blowing towards the bedrooms.
But this does mean that you have to keep the doors open at night or suffer some temperature drift. A head in each bedroom would be significant overkill.
Hi Peter. I'm near Vancouver, BC on a small island by the sea.
In Ontario, you have to be a licenced HVAC to buy a mini split, except for China specials off Amazon, your online options are limited.
Your best bet is to source from the US and ship to a P.O box across the border.
As for your setup, I'm with Peter. Budget is a central mini split but your bedrooms will be always a bit colder or hotter than the living space. A head in each bedroom is a bad idea, bedroom loads are well bellow the minimum on the smallest multi split.
If you don't mind ductwork, your best bet for comfort is a low static ducted unit.
Looking at your layout, you can do a ceiling mount above the toilet in your en-suite or in your entrance hallway. This would give you a simple return to the main living space and pretty straight forward ducting to feed all your rooms.
"Looking at your layout, you can do a ceiling mount above the toilet in your en-suite or in your entrance hallway. This would give you a simple return to the main living space and pretty straight forward ducting to feed all your rooms."
When you say ceiling mount, what is it that's mounted? And then supply ducting to the bedrooms? Does this require an air handler?
Not sure if I'm about to commit blasphemy around here, but...what about a single unit for the main part of the house and electric resistance baseboard heaters in the bedrooms for supplemental heat if/when needed? If your part of BC is served by hydro for electric then your rate and environmental impact wouldn't be that bad using a little electrical heat when needed. If you have PV then even better.
Andy,
That's not blasphemy. Many members of the GBA community, including Marc Rosenbaum, have used or recommended that approach.
Note that "supplemental" bedroom heat will be 100+% of bedroom heat unless you allow the bedroom to be cooler.
We like to sleep in a cool bedroom, 18-19C so we're more concerned with keeping the bedrooms cool in summer than heating in winter. Malcolm Taylor put me on to a baseboard heater that uses an outlet which we can use as supplementary heat.
If it helps, I found a free online Manual J calculator at CoolCalc. I suspect it will provide more accurate results than most contractors and will cost you nothing.
I'm also in the process of designing a heat pump system for my house, so I don't have any successful experience to relate.
I decided to go with a low static pressure unit in my upstairs as well. It's not as ugly to look at, it's presumably quieter (depending on where it is), and I can heat multiple small spaces with a single unit which means less stuff to buy. I discovered that duct design is tricky. You might want to try EnergyVanguard or some similar service- I may do the same.
The difference with the (H) model is the extended low temp operation. It's rated down to -15F and will continue running at a reduced capacity beyond that. Being coastal you may not need the 9RLS3YH model but you may find the up charge is small. What's your design temperature?
The 1:1 mini splits are much more straightforward for a mostly DIY install. But, I would get an HVAC pro to vacuum and charge the line set. Multi splits have a lot of variables going into the system selection and install that warrants professional involvement.
If you do go with one head I would try and find a position that discharges towards the master/entry to encourage air circulation(Perhaps on the outside wall near the TV). Most of the air on a wall mount head comes out pretty much straight (the right left control on the louvers is minimal in my experience).
If you are trying to keep your contractor situation simple, going with a single ductless head and some base board heat is probably a smart way to go given your mild climate (for both heating and cooling).
If you didn't have a contractor sourcing problem, I'd recommend getting a single ducted cassette, and hide it in one of the closets near your entrance or master bedroom, or maybe a bump out behind the en-suite toilet.
Minisplits are available at HVAC wholesalers here in Canada (Fujitsu specifically), so your contractor doesn't need to be a Fujitsu guy, especially if you've outsourced your load calcs and can make an informed equipment selection. Be prepared, most contractors will push back at the tight sizing, ( I have a 3/4 ton unit effortlessly cooling (I never take the fan speed off the lowest setting) my whole house with a high shading factor in Southern Ontario, but the contractors in my area wanted to install a 1.5 ton unit ("for hot days").
Thanks for this Josh. The design temperature for this area is -7 Celsius.
What advantage would a ducted cassette have?
The main advantage is getting good distribution without the over sizing that typically comes with putting units in every room. The downside is you've re-introduced costs and complexity since good ductwork isn't cheap, and likely won't function well without proper design.
But, your house is small enough that if the interior doors are open and you have a well insulated air tight envelope the temps are going to be within a couple degrees. It depends on what your expectations are and tolerance for temperature variances.
If you go with a single ductless head, you can try and stagger your setpoints a bit so the ductless unit does the heavy lifting. You don't want the baseboard heat supplying so much heat that the ductless unit shuts off. I'd suggest a small baseboard heater in each bedroom, and maybe electric floor warming in the ensuite and bathroom. Floor warming helps to make colder space temps more tolerable.
I would recommend going with a cold climate model of heat pump. The Fujitsu you mentioned is a good one for a wall mount. Mitsubishi, and LG make good wall mount units as well but be careful to get the cold climate models.
If you go compact ducted the Fujitsu unit is really in a class of it's own. It has a cold climate compressor (but no base-pan heater), and decent fan performance. Mits or LG don't have anything that compares directly in a 1:1 arrangement.
Alex,
Take a look at:
https://ashp.neep.org/#!/product/25312
http://www.fujitsugeneral.com/us/resources/pdf/support/downloads/submittal-sheets/ARU12RLF.pdf
The indoor unit mounts to the ceiling and you run all your ducts to it. If you are careful, you loose about 9 to 10 of ceiling height to the ducting and bulkheads. This sounds like a fair bit, but once installed most people never notice. In your case most of the ducting would be through closets and above doors anyways.
To see if you can make it work, roughly you need to find a space for:
-24x8 return duct and a 24x25 intake filter
-7" duct to the bedrooms, 4" to the bathrooms, 12x8" to living 10x8" to kitchen
Could I just run this unit to feed the living room/kitchen from above the closet next to the living room and duct to the bedrooms? Is there a need to run ducts to the kitchen or bathrooms?
If the unit is located centrally and you have some nice double deflection diffusers, you don't need to run all the way over to each exterior wall. As long as you can throw some air in the right direction without a wall being in the way.
The bathrooms would take so little duct work, I would still run something to them. B/R2 would be the only run that really has any length at all.
You might be able to get professionally made supply and return plenums with the proper takeoffs, and then use readily available round ductwork to get to the bedrooms and bathrooms DIY.
Without dimensions, this is just a rough idea. Looking at it now, it might just be simpler to put the unit into the hallway since you need a bulkhead there already.
You will need some high throw diffusers in the living space. A bit of resistance floor heat in the kitchen and entrance hallway to get warmer floors would help with taking the edge off in the winter time.
Josh, Akos, thanks so much for the help. Lots to think over. What effect does an HRV have on heat distribution? Would it help even out temperatures?
Coolcalc gave me heating loads of 8,000 btu and 6,200 for cooling.
An HRV will bring in air that is too cold and too dry in the winter and too hot and too humid in the summer. Also the air flow is pretty small, even if you manage to pre-heat/pre-cool the air it will not provide enough BTU to make a difference.
With such a small load, if you don't mind a bit of hacking, you can use a bath fan mounted bellow the outlet of a wall mount to transfer heating/cooling to the bedroom. If you inset the wall mount or pop out the fan, you should be able to pick 18C air, with a 110cfm whispergreen fan, that would move around 1100 BTU into a 24C room. Don't know if that is enough for you, two people sleeping is about 600 BTU.
If you plumb your HRV backwards (stale pickups from the bedroom and bath, fresh air feed to the living space), that would also move a couple of BTU from the living space, but it would be very small.
Akos, were you suggesting an HRV wouldn't be ideal in this climate and suggest an ERV, or simply that the HRV would do nothing for heat transfer between rooms?
The latter. The HRV/ERV won't provide any amount of heat/cool (it will actually make the rooms slightly worse) because the air that it is supplying is only semi-conditioned by the core.
If you plumb it in reverse (supplying fresh air to the living space, stale air pickup in the bedroom), it will move a VERY small amount of BTUs into the bedrooms, not enough to matter.
I thought I'd revisit this with an update/cry for help. Finding a contractor who is available/willing to come to my location is proving immensely difficult and I have exhausted all the recommendations I've had. The lone quote I received suggested a 2 tonne compressor, 2x 9,000btu evaporators for the master and living space and a 7,000btu evaporator for the smaller bedroom for over $13,000 which is just ridiculous.
This is pushing me towards a DIY minisplit installed centrally as discussed above, although I think I could do the slim duct unit if I had the layout and ductwork designed for me.
Similarly, my HRV options are limited to a quote received from Zehnder which was much more than I had anticipated and so I'm considering a 3rd party designed self installed system here too.
This is all a long winded way of asking if anyone in this thread provides any of these services professionally in Canada, or can recommend someone who does. I have contacted EnergyVanguard but I don't know if they'd be able to sign off on the ventilation checklist I'd need for occupancy.
> over $13,000
At that price, I'd look into a DIY install of an Arctic or Chiltrix air to water heat pump with fan coils. No refrigerant plumbing needed.
Even quoted in CanaDinars/ Loonys that would still be a fairly steep USD$9880 at today's exchange rate but not totally out of the park for a name brand cold climate multi-split. Individual mini-splits in my neighborhood generally come in about $4K/ton, sometimes less in competitive bidding. Multi-splits tend to be more expensive, and the additional 7K head for the third zone costs something.
But 2 tons it a bit overkill for a ~1000' house in that climate. A 1 ton mini-ducted Fujitsu 12RLFCD can deliver ~18KBTU/hr+ at the local design temperature, of +24F/-3C, (the 99th percentile temperature bin at the Vancouver airport) which would be something like a 1.5x oversize factor for typical heat loads of tight well insulated (not superinsulated) houses that size.
https://ashp.neep.org/#!/product/25312
https://articles.extension.org/sites/default/files/7.%20Outdoor_Design_Conditions_508.pdf
In my area even with cost adder of running ducts the 12RLFCD would run about USD$7K / CDN$9K all-in and you'd have something that modulates down to 3100 BTU/hr @ +47C/+8C (your normal summertime temperature on the islands! :-) ), whereas the multi-splits don't go lower than about twice that, and would be doing a lot of on/off cycling of the compressor even at your average winter temps.
Duct design for a house that size and shape isn't rocket science. To keep the static pressures low consider using a big pleated filter such as an Aprilaire 2400 and a common return. Calculate the duct loads, and divide the 383 max cfm of the 12RFLC to the load. Make a short fat supply plenum and design the duct sizes to the individual rooms/registers for a nominal max duct velocity of 350-450 feet per minute (less is OK.) The runs won't be very long- even flex duct would be fine as long as it's stretched tight, with no short-radius turns (hard piped ells would be better.) Design in balancing vanes on each run for fine tuning it.
If you don't have/can't get a Manual-J, use loadcalc.net (going room by room) and presume both the ducts and house are completely air tight or it'll oversize it by 50% or more from reality.
An ERV doesn't really buy you much in that climate, where outdoor dew points are in the comfortable & healthy range year-round. An HRV would be the way to go, ducted independently from the
My comment about the quote being ridiculous was directed more at the fact coolcalc gave me heating loads of around 8000 btu, and our designer also thought a 9000 btu single minsplit would be sufficient. So heads totalling 23000 btu of output seem grossly oversized
Dana, with that 99th percentile temperature being warmer than the values I found, do you think it's worth getting an RLS3H or just the RLS3. I found the list prices of the sole BC distributor for Fujitsu and its a $400 price difference, 4300 vs 4700 CAD.
Barely minutes after I posted my previous comment a contractor got back to me with a far more reasonable and detailed quote for a central minisplit and a couple of other options. Relief.
When I was getting mini split quotes, I did not give them the opportunity to quote ridiculous things. I specified the exact unit and asked for a price.
I am in zone 6, and even with only a $150 price difference it was a coin toss for me but went with the H model. In your climate, it would be automatic for me, save the $400 (and some electricity, as the H model has a slightly lower HSPF).
Another option is buying one from sogoodtobuy for around $1300. Lower efficiency, but you can buy a lot of electricity for the $3000 price difference. You might have to do it after the building inspector has come and gone, as I don't imagine they would take kindly to the DIY install. You can find an HVAC guy to do the final hookup and leak test, but those guys usually work under the table so it doesn't help you from the inspection standpoint.
What Trevor said. In your location there's nothing to be gained with the -H versions other than slightly higher power bills than with the non-H during sub-freezing events.
A ducted option is probably going to be the best choice here.
>"Dana, with that 99th percentile temperature being warmer than the values I found..."
I'm curious- what design temperatures were you finding (and from what sources?) In my mis-spent youth I can recall a few times when it hit -15C at sea level in the Puget Sound region of WA, but those were extremely rare. Even -10C isn't likely to happen every year.
I found -7 Celsius from the source below which is the closest recorded location I found. However, it does seem like an unusually low temperature. We had a day or two at -6 last winter and that was the coldest I can remember in the last few years.
https://westvancouver.ca/sites/default/files/dwv/assets/home-building-property/permits-and-licences/snow-load-zones/SNOW_LOAD_AND_CLIMATIC_DATA.pdf
When you say ducted would that be a slim duct system as was suggested earlier in the thread or full ducted with and air handler? The Daikin DZK was suggested as a possible option.
If you are looking for the design side to pass inspection, the simplest would be to put in some electric baseboards and call it the primary heat source.
For the ducted unit, you can ballpark most of the sizing yourself, if in doubt just upsize the ducting.
I would ask the HVAC guy what they would charge to install the cassette provided all the ducting is already in the house. It should be way cheaper than the 3 headed multi split.