Multi-Head or Pair of Singles?
I’m about to place an order for mini-splits to take over most of the heating in my house (two levels, both heated, 1500 sqft each, the bottom level is a walkout on slab).
Per my previous posts, I’ve satisfied my self that my total heating demand at a design temp of -5f is about 44kBTU, this based on fuel consumption. Loadcalc.net comes in about 15% higher. Loadcalc estimates approximately event heating requirements on both floors.
I plan to put one head downstairs and one upstairs in large mostly open areas. This mimics the current config where I have a NG insert in each of these areas , they work well except for the temperature swings between heat cycles and are almost 25 yrs old.
I will use the mini split heads mostly for heating (99% design temp of -5f) and cool maybe 2 weeks per year. I would like to dehumidify downstairs when upstairs is off but the downstairs is already cool enough so I’m not counting on the drying mode to be effective without over cooling the downstairs
I’ve narrowed down to two options, both Mitsubishi.
1. 2 X 18kBTU H2i
2. 1 X 4C36 multi-split H2i with three heads (2X18 + 1X6).
Option 2 has the advantage of allowing an extra head (6k 75′ from the compressor), and has a bit more low temp capacity. It will cycle at 47f as it’s minimum capacity is 22 kBTU vs a house load of 15 kBTU.
Option 1 should work without cycling at any heating temperature and it is just shy of the heat demand requirements at -5f. It’s main advantage is the better turndown ratio and independence of operation on the two house levels.
Other than at high ambient heating (47f), the COPs appear to be about the same down to -5f. Backup existing baseboard electric and NG inserts will remain so handling extreme lows isn’t a concern.
The way rebates are working in Canada, the cost of either option is almost the same.
Any thoughts on which option I should go with will be appreciated as have been the thoughtful and useful replies to my recent posts.
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