Central Air vs Ducted/Concealed Mini Splits vs Unico for AC

I already have a gas furnace/forced air system — it’s old but gets the job done. I’d like to get an air conditioning system that’s hidden. Should I simply add air conditioning to my current system or is it worth the $$$ to try and hide ducted mini splits or potentially a unico system? I’m doing other renovations, so the work of hiding the potential new ductwork isn’t a large inconvenience. I don’t want to spend money on something I don’t need but I would hate to be uncomfortable & unhappy with the cheapest solution. WDYT?

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in General Discussion 4 years and 4 months ago

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hkapstein | 4 years and 4 months ago

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@bobmarvin, HVAC engineers are underated in the townhouse market. It might seem like overkill to spend a few thousand bucks for someone to design a minisplit or central system for a townhouse, and that’s true if everything works, and the HVAC techs are experienced. But an engineer can tell you how to size units and ductwork to balance the system, and make sure air is properly distributed, and answer questions about floor registers etc.

All I can say is I’ve had floor registers, and they worked just fine for cooling. Probably they’d work better on the ceiling but they got the job done on the floor. I don’t know if your situation with 1899 ducts would have worked. Heating loads are usually larger than cooling loads here, so if you they delivered enough heat, I’d speculate they could deliver enough AC, but there may be other concerns.

RobertGMarvin

in General Discussion 4 years and 4 months ago

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Hmm. Unfortunately Urbandad’s answer is 40+ years too late for me. We passed on a relative’s offer to pay for central air back when we bough our house, after being advised that our 1899 heating ducts wouldn’t work properly. Oh well!

daveinbedstuy | 4 years and 4 months ago

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If you have the ductwork, go with that. I have a ducted AC system in one house and a UNICO in another. I like both equally well.

hkapstein | 4 years and 4 months ago

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Low registers will work for AC. I’ve owned properties with all floor registers for AC only and it worked great. If you’re designing a brand new system, it may be more efficient, or more likely to cool evenly if you deliver the cold air from the ceiling, but in my experience, it’s probably not worth re-ducting just for that advantage, but hey it’s your money. There may be issues with the duct sizing, but if the ducts are sized for heat, probably they are big enough for AC.

I wouldn’t put in a unico system. Unico is a technology known as a high velocity system. Smaller ducts deliver conditioned air at higher speed which allows the same amount of air to arrive in the room. The earlier concern was that the ducts could be noisy if not installed perefectly, they can hiss or whistle. However the newer problem is that the fan must consume a lot of power to force are at high speed through small ducts. One way newer AC systems are energy efficient is they use very efficient fans that gently push air through larger ducts. Unico systems are unable to meet the current efficiency r equirements, and so they may be on their way out. Hortizontal ducted minisplits would be a better technology in my opinion for many reasons. They are quiet, they are easier to zone, and they are efficient, but they do require a soffit or joist bay that is appropriately configured.

RobertGMarvin

in General Discussion 4 years and 4 months ago

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Many years ago I looked into having AC added to my existing hot air ducts. My house has the original 1899 ducts with the addition of newer ducts to the kitchen (originally heated by a coal stove) and the laundry room (original maid’s room) plus a return duct for the current forced hot air furnace. I was told that the placement of the hot air registers, on the floor and low down on walks) was wrong for AC and that the old ducts might be too small. Of course that was back in the 70s—maybe things have changed.

Guest User | 4 years and 4 months ago

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Yes to ducted and you may be able to use the same ducts. Not sure about Unico – my hvac person told me it’s outdated. I like Unico in theory.