Replies

1. Expert Member
   Dana Dorsett | Apr 03, 2019 10:00pm | #1

   Cooling only?

   The head per room approach almost always leads to grotesque oversizing and lower efficiency/comfort. The number of bedrooms and floor plan/layout isn't specified. A floor plan with the loads of each room specified would be more useful.

   Mini-duct cassettes can split the output between multiple low load rooms. The loads for the master bedroom seem a bit high for a 240' room, but possible, and it could use a 9K head on a multi-split or an FH06 single zone minisplit if those loads are real.

2. 
   rhl_ | Apr 03, 2019 10:48pm | #2

   I want to size it for cooling. We already have hydronic heat. So the heating system in the minisplits could be supplemental. I did that manual J myself.

   The heating side of things does seem to roughly match my actual usage.

   I attached another version which is the same general idea, but assumes i insulate all the walls and attic etc. It also have the floorplan layout in it.

   
3. 
   twoodson | Apr 03, 2019 11:19pm | #3

   Ryan, does this home currently have ductwork?

1. 
   rhl_ | Apr 04, 2019 09:20am | #5

   Nope.

4. 
   Deleted | Apr 03, 2019 11:46pm | #4

   Deleted

5. 
   rhl_ | Apr 04, 2019 11:30pm | #6

   Dana, i've attached a set of floorplans with the cooling loads from the manual J written directly on each room in the two floors i care about conditioning. I don't need to put into the basement. Perhaps this is not clear, but there is a 16' frustrum ceiling in the living room, and a large like 32-36 sqft window in the living room. (currently a very leaky, single pane thing).

   Also these are the numbers out of wrightsoft, it doesn't necessarily seem to add latent loads into each room, and the latent load calculations per floor seem surprisingly low for how humid it is in the summer months.

   
6. 
   monkeyman9 | Apr 05, 2019 09:36am | #7

   I'm in the same boat as you. My only option are oversized heads or mini ducted on attic floor with a foam board cover and spray foam on ducts and plenums...then blanket it all in maybe r60.

   My master suite area could have the mini duct in the closet with a lot of work. But the other 2 bedrooms are 10ft apart at the closest walls. So those ducts and mini duct unit would be in the attic no matter how I cut it.

   I really wish they'd make a 3k wall unit.

1. 
   monkeyman9 | Apr 05, 2019 09:39am | #8

   One thing you may consider that I thought about is having a head in the hallway with a through wall fan or jumper ducts to the small bedrooms. I'm not sure how this would work out and it complicates the system. Maybe someone else can comment there.

1. 
   rhl_ | Apr 05, 2019 04:36pm | #9

   Or the other option: size the outdoor unit to the house load, and the indoor units to match as close as possible (but oversized relative to the outdoor unit), I wonder what happens?

   Air to water systems (such as space pal) have smaller indoor heads, however the outdoor units for space park are terrible. One question is if it’s possible to use a Mitsubishi outdoor unit, hooked up to a buffer tank with a heat exchanger. Could this be done while maintaining high efficiency.. (or just import the units from England or something)

7. 
   1910duplex | May 20, 2021 10:25am | #10

   What did you end up doing? I am going to go with a ducted minisplit for cooling, and am in 4a, am interested in how happy you are with your set up.