Thoughts on this minisplit unit for a primary hvac unit..

[mcdougy]

The unit specs are in the attached pdf link posted at the bottom of the page. Mitsubishi MXZ 3C30NAHZ3-U1 it's a hyper heat 30k inverter with multi heads (3)

Considering this unit with a 6k wall unit for a 12'x17' bedroom, a 9k for a 16'x22 master bedroom including a ensuite, and a 12k for 24'x26' main open area.
Zone 5b (IIRC) in Southern Ontario.
We often have 2-4 weeks of sustained -15 Celsius lows in the winter and 2-4 weeks of +30 Celsius with 90% humidity in summer.
This is a retrofit to the existing home and will be the hvac for an addition that is about to be added.
Current house (11yrs old) and addition would be considered well insulated, with a proper air barrier and vapour barrier, and normal amount of glazing. The current house has no a/c and is heated via a hydronic radiant heat in the Slab (no basement). They are wanting AC to be added to the current home and this has brought them to the mini split query, a mini split system would add the central air conditioning and supply the only heat source for the smallish addition (master bedroom area and office =600sqft).
They are hoping to not use the propane fired Boiler for the infloor heat once the mini system is/if installed. Baseboard heaters will be installed as backup incase of a system failure
Does this hvac plan and equipment seem like a realistic and cost effective plan?
I have zero experience with the performance of a mini split system and that's why I am asking for opinions and experiences.
Is this unit overpriced when its compared to "off brand" equipment of similar performance?

 

[Riverbanks]

I know of 2 Mitsubishi installs near me, they both are very happy with their choice

 

[stoveliker]

I don't have a hyper heat, but I'm very happy with my Mitsubishi 4 head minisplit. Using it to heat when it's 40 F or above for 24 hrs or more and cool in summer. Very silent, good efficiency, and I took the wifi option with it so I can control it with my phone (or a normal remote).


I am not expert enough for the main questions.

 

[EbS-P]

I don't have a hyper heat, but I'm very happy with my Mitsubishi 4 head minisplit. Using it to heat when it's 40 F or above for 24 hrs or more and cool in summer. Very silent, good efficiency, and I took the wifi option with it so I can control it with my phone (or a normal remote).


I am not expert enough for the main questions.

What head sizes?? Any condensation pumps?

 

[stoveliker]

18000 BTU in my living room (only one on the main 1200 sqft floor that also has kitchen, full bath, master bed, fairly large guest room, and my office), 6000 BTU in the basement (mostly running in the dehumidification mode, and it has a condensation pump to get the water over the concrete wall as the basement is mostly underground on that side), and a 6000 BTU one in each of my kids bedrooms above that. Those bedrooms catch some sun as they have south facing walls and windows.

The (finished, insulated - but not moisture sealed, grmbflh) basement had to run a dehumidfier constantly in summer (I live half a mile from salt water). Now it's just chilly and dry in summer. Cool living room floors

So 18+6+6+6.

Outside unit is MXZ-4C36NA2.

 

[mcdougy]

The unit has been installed with the 3 heads. 12k 9k and 6k. No condensation pumps, just gravity feed to a buried drain pipe and comes to a perforated drain line. The electrician hasn't ran the power yet to allow us for a first run of them.
I hope they work well, they were the most logical solutio to this addition......time will tell.... I am slightly nervous of the multiple heads on 1 outdoor unit. But 3 outdoor units would have looked odd possibly. The outdoor unit that is installed is significantly larger than the single units though.

 

[stoveliker]

3 indoor on 1 outdoor is less efficient, but for me it works great. Power usage is really low. And I'm amazed at how much heat they can put out when it's 25 outside. Enough to heat my home, if needed. (But below 40 I'm using the stove because efficiency does go down below freezing. However, a quick shot of heat in a 30 F morning I told the sun helps, is quite easy and quick.)

 

[mcdougy]

3 indoor on 1 outdoor is less efficient, but for me it works great. Power usage is really low. And I'm amazed at how much heat they can put out when it's 25 outside. Enough to heat my home, if needed. (But below 40 I'm using the stove because efficiency does go down below freezing. However, a quick shot of heat in a 30 F morning I told the sun helps, is quite easy and quick.)

This is in a new build addition, and it will be very efficient to heat.....some large windows are not an asset, but being draft free with r32 walls ,r60 attic and r10 under the slab will produce good envelope efficiency. I'm hoping for the best. These units will be tested to -20 + Celsius most winters (hopefully a short period.) The units claim they will produce heat in this temperature range.

 

[stoveliker]

Yes. Mine have a minimum of 5 F, i.e. -15 C. But the efficiency then is getting low. Still larger than 1, so better than resistive heating, but I think just below 2 then.

Ah well, the stove works well below 45 is.

 

[peakbagger]

The key with these units is to set them and forget them especially in very cold weather. It can take hours to raise the temp a few degrees. The other thing to do is keep a close eye on the outdoor unit when it snows. You may need to rig up shields to keep snow from blowing or sliding into the unit. There are optional shields sold by some firms that work pretty well. The key is leave plenty of air space on all sides, you want to keep the snow out while letting the air in. Its pretty much required that the outdoor unit is mounted up off the ground with enough height to be above the surrounding snowpack. If its just sitting on the ground be prepared for a cold winter with the unit going into defrost frequently.