Mini split sizing/placement
We’re considering installing a multi-zone mini split in a 915sf home. The house is 100+ years old, mostly plaster walls, good insulation in the attic and in the rear walls of the house (which have been replaced)– the rest, we aren’t sure. We are in zone 4.
The big front room has 9 ft ceilings, the back bedroom has 7 foot ceilings.
The dining room has a 9 foot ceiling– this room adjoins the kitchen (no separation), which has a 7 foot ceiling.
Kitchen and back bedroom receive afternoon sun.
At the far end of the large living area is a second bedroom that closes with a sliding wall (marked with a red dashed line). The wall is only closed at night, otherwise, we leave it open as one space with the living room.
We were considering a 4 head system, but in DIY kits, they only come in 36k BTU. That seems oversized from what I’m reading. The most appropriately sized option seems to be a 24 or 27k with 3 heads.
Here are my questions:
1) Could we put a 12k BTU unit over the window at the far end of the large room (as part of the bedroom with the sliding wall)– would it be capable of conditioning the living space during the day? Sf is about 350 for both spaces. The sliding wall (bedroom) portion accounts for 130 of that.
2) Are we better off to do a 9k in the living room, and a 9k in the “bedroom” portion? It seems that the air flow would be improved, but I’m wondering if 18k is oversized.
3) Is a 9k unit critically oversized for the 100sf+ bedroom in the back? It seems it should be more like a 7k, but they’re not available that small in DIY models.
4) Do you think the kitchen will be adequately cooled if a 12k head is placed over the front window in the dining room? Sf of the dining/kitchen is around 215. Ceiling drops from 9ft to 7ft between the dining room and kitchen.
Thanks for considering!!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part