Single ducted mini split for three rooms?

Users who are viewing this thread

Jason215

New Member
Messages
1
Reaction score
0
Points
1
Location
Philadelphia PA
I need to cool three small rooms (LR, bath and kitchen) on the first floor of a row house in Philadelphia PA. My idea is to install a concealed duct mini split in the basement and have three short run ducts going up through the floor into each room. I would have one return vent in the LR returning air to the back of the air handler in the basement. My basic question is will this work? I have installed mini splits before but never one using ducts.

The unit I’m considering has a max CFM of 530. The total sq ft to be cooled is about 500. I would create some kind of duct splitter to attach to the supply side opening. Here’s the unit for reference: https://www.pioneerminisplit.com/co...lit-air-conditioner-heat-pump-system-full-set

I appreciate any feedback people have.
 

Dana

In the trades
Messages
7,889
Reaction score
509
Points
113
Location
01609
That particular 1.5 ton unit would be ridiculously oversized for cooling and heating 500 square feet of space. It's minimum cooling output is 6400 BTU/hr, which might even be bigger than the design cooling load of that space. Crummy old school rules of thumb are usually "a ton per 750 square feet" or "a ton per 500 feet", all of which oversize even an uninsulated air leaky tarpaper shack in Louisiana. A row house in Philly is more likely to come in at about a ton per 1500-2000', except for maybe a top floor unit with west facing windows and only R13 in the attic. A 500' first floor unit would likely be under 5000 BTU/hr unless it has unshaded west facing windows. If it's cycling rather than modulating it's not going to be drying out the air as much, nor will it hit it's efficiency numbers.

There are some 3/4 ton mini-duct cassettes that might make sense though. Run a coolcalc &/or loadcalc heating & cooling load calculation on these rooms using aggressive assumptions on air leakage (pretend it's air-tight) and R-values.

At the low-priced end of the world for about a grand a 3/4 ton Midea can throttle back to 3500 BTU/hr in cooling mode and ramp up to 11,000 BTU/hr of cooling if needed (probably never). Should be less than a grand for that one. (Carrier's mini-splits are now all manufactured by Midea. Some of the better compressor technology in Mideas are from Toshiba.) The 3/4 ton Pioneer could be decent option too, with cooling output between 3000-11,300 BTU/hr.

Building a short plenum with 3 round duct outputs would allow you to install balancing vanes to temperature-adjust the rooms. If flex duct is usedt try to keep it super-short, none of these things can drive as much static pressure as a full sized air handler.

Run the load numbers and report back. There are other options out there.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks