Reach 4 rooms with 1 hallway mini-split ducted cassette?
Hi everyone. I am currently renovating the first story of a two story, two family house built in the early 2000s, climate zone 4a (New York City). This first story has its own zoned ducted natural gas furnace, located in a finished basement, that heats and cools the basement and first floor.
Because the system is already going on 20 years, and we are doing major renovations, I’d like to get some updated HVAC work out of the way. Ideally, I can convert to mini split electric heating/cooling, and be set up down the line to power much of the house using solar panels.
The conundrum I’m facing is that I don’t estimate the heating and cooling load of the house to be very high, and so I think putting a separate blower in each room would be overkill and result in an oversized system. I’d also like to avoid running entirely new ducts into every room for a ducted mini split system.
My idea is to put one ductless blower in the basement, and a single ducted cassette on the first floor in a hallway at the intersection of 4 rooms. A photo is attached, with the approximate cassette location circled.
I am thinking that a cassette located in this spot could push air into all 4 rooms, since all 4 rooms are located around this suggested cassette location. The plan would be to keep doors usually open.
Any thoughts on if this is even worth exploring? Do ducted cassettes have enough blower force to accomplish something like this?
Thanks for any insight!
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Replies
Have you considered a ducted split?
If you do not have the ceiling height to build out a soffit, perhaps a closet ceiling
Why don't you just replace the existing furnace with an all electric ducted split system? The ducts are already in place and you'd just need to replace the equipment with new equipment or am I missing something?
Thanks for the suggestions. A ducted split could certainly work, but I’ve heard that furnace ducts and mini split ducts are different sizes, because the systems produce different amount of pressure?
I think I might need to rip out all the old ducts and put new ducks if I’m going with a ducted mini split?
Ducted cassettes can be used in this situation. I've done something similar with ducting the unit to 3 bedrooms plus 2 baths in a "pretty good house" and it worked well. You can get medium static pressure units that can deal with longer duct runs: https://www.fujitsugeneral.com/us/products/split/msp-duct/index.html
But you shouldn't have to worry about it too much since your rooms are close together and this great article from Allison Bailes talks about designing a system properly for a low static pressure unit: https://www.energyvanguard.com/blog/busting-myth-about-low-static-ducted-mini-splits
The main concern is that the ducted cassettes are much larger than you would expect once you add in access space, ductwork, and a good sized filter cabinet. Don't skimp on the size of the filter cabinet as a large and thick filter will help reduce the static pressure on the system along with protecting the coils from mold growth due to dust build up.