Supplement A/C with Ductless Unit(s)?

1,040 Views | 6 Replies | Last: 6 yr ago by jcurtis2979
Sooper Jeenyus
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AG
Have a large house and get hot spots during the summer. Anyone tried supplementing their central A/C with a ductless unit or two in specific rooms?
EMY92
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AG
You could probably fix the problem with the ductwork being fixed. Even without seeing your house, I'm 99% sure that your ductwork is crap.
ukbb2003
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EMY92 said:

You could probably fix the problem with the ductwork being fixed. Even without seeing your house, I'm 99% sure that your ductwork is crap.
Second this. and you would save thousands.
Sooper Jeenyus
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AG
Ductless units aren't that expensive. I'm skeptical the cost to replace the ducts would offset cost of ductless units by "thousands."

I'm open to the possibility but I don't quite share the optimism...
jamesf
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AG
We have a ductless to supplement our AC, but it is in a room that is an addition that didn't have an AC vent. I would get an HVAC tech out first to see if he can do some rebalancing or something to fix it.
ukbb2003
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Sooper Jeenyus said:

Ductless units aren't that expensive. I'm skeptical the cost to replace the ducts would offset cost of ductless units by "thousands."

I'm open to the possibility but I don't quite share the optimism...


If you are talking mini-splits, they aren't cheap. OP mentioned possibly installing more than one. In that case the difference would be substantial.
Koko Chingo
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AG
Short answer - I think EMY92 is right. Ducting issue. You may have some leaks. If you need add ducts you may have to enlarge your return air opening a size or two, either way it is not that big of a deal and a whole lot cheaper than a mini-split.

Long Answer -

When I lived in Japan, min-splits were everywhere. What makes them effective over there is the way houses are laid out. You can close off rooms so that each mini-split is cooling (or heating) a defined space.

Most American homes are more open and a ductless mini-split is not the best choice.

You could put a mini-split in each bedroom room. Going that route, you should then remove the ducting to those bedrooms from the central A/C. This is just really expensive and still may not eliminate your hot spots depending on where they are.

Mini-splits are great for additions, retrofitting where there is no space for ductwork, or new designs where each room is designed with having mini-splits as the HVAC system.
jcurtis2979
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AG
Get an air balance done on the system and that will tell you what the problem is. If you have flex duct work that is the problem. (or at least one of them) Have them verify proper return duct sizing and then rebalance after duct alterations are made. (might need more return air) If the unit is sized properly for the house you should be able to balance it to offset microclimates.

I know on my 1981 house none of the metal hard pipe was sealed. After figuring it out one winter I stripped off all insulation and sealed the duct work and then reinsulated the duct which made a large difference in temp and humidity. I am also an HVAC contractor but it is fairly easy work just tedious and messy.
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