Mini-Duct HVAC systems

[Le Poisson]

Does anyone on here have experience with these heat systems

https://www.unicosystem.com/
http://spacepak.com/

If you have one, how well has it worked for you? And if you had it installed, what kinds of factors affected price? I haven't seen these around here, but it sounds like a perfect solution to a heat/AC problem at a historic home we just bought. I can't find anything about pricing anywhere though.

[rothwem]

I looked into one of these and it was substantially more expensive (2x) than the ducted mini split setup we ended up installing.  There was also only one installer in our area, and I think they really only dealt with high end clients in the historic part of town. We are decidedly not high end.

[Le Poisson]

I've seen a lot of people go minisplit. I did not know they could be ducted.

Is it very loud when yours kicks in? How visible is the unit?

[rothwem]

I've seen a lot of people go minisplit. I did not know they could be ducted.

Is it very loud when yours kicks in? How visible is the unit?

Its extremely quiet, I have to feel the vent to make sure its on.  The unit is very visible...in my crawlspace.  Basically it uses the mini-split outdoor unit attached to an air handler in the crawlspace that runs to ducts and out registers cut in the floor like a normal ducted system. 

I went this way because I was adding central air to a 1950s duplex that had two 700 square foot units and I wanted separate HVAC systems for each, the mini splits were the only unit small enough to prevent short cycling. 

[Le Poisson]

Mine is a 1700 SF lower unit, 1700 SF upper unit and a 1000 SF bachelor addition on the back of the house. I wonder if I could put the minisplit off the back and run ducts forward.

[Jon Bon]

Yeah I have family that has this. Pretty what you think, fancy old homes that are having AC added, popular in places that have radiator heat and zero ducts. It is VERY high end, so they are used to dealing with a customer who is not price sensitive.

I mean it was featured on this old house, so you know its expensive AF.

[rothwem]

Mine is a 1700 SF lower unit, 1700 SF upper unit and a 1000 SF bachelor addition on the back of the house. I wonder if I could put the minisplit off the back and run ducts forward.

Ah, so its a triplex?  A three unit system might work for you. 

Mine was $6000/side though, just FYI, so not super super cheap.  And the electricity needed to be upgraded since the mini splits needed a 40 amp supply and each side was on a 60 amp box.  A ductless mini split would've been considerably cheaper, but the mounting would've been tricky in the house and the lines would've been very visible. 

As a point of comparison, the mini duct guy quoted just over $22k to install. 

These are American dollars, btw. 

[Le Poisson]

I'll be busting walls open for plumbing work this week, so if that presents opportunity, I may as well run ducts then for some kind of mini system (or at least not close them up right away. OTOH, if these are as $$$ as you are saying, maybe I don't.

Boiler is up for replacing, and it's going to cost $15,000 anyway. Maybe I'll schedule some quotes while I'm up there.

And yeah, the "pretty" factor is strong in this old dame. It's a 175 yr old home that's been in the same family for the past 70 yrs, so well maintained (with the exception of galvanized plumbing that got away from them).

[clarkfan1979]

Mini-splits w/o ducting are very popular in Hawaii. Hawaii has the most expensive electricity rate in the country at 37 cents per kilowatt. Mini-splits are more efficient than central air, so they are cheaper in the long-run. I'm not sure how many years to break even. I'm guessing 5-10 year range.

The mini-splits also make more sense for smaller homes with less rooms. I don't think it would be cost effective to have more than 4 mini-split units in one home. 

[malacca]

I have used similar systems in Asia for 30+ years (that is all they have). But for some reason they triple in price here.

I actually ran into one system recently in a house that I was looking at. It is in a cold climate and had in-floor radiant heat - so it didn't have any vents.

I think they are not any more or less reliable than central AC.

But they are more mold prone. And since they are usually installed in inaccessible spaces they are hard to get at to clean.

[Milspecstache]

I installed a system in a house I built.  Upstairs had 4 indoor units paired up to the outside unit and downstairs had 3.  Professional company quoted me $10k per floor, acknowledging that working together me and the owner would take one day per floor to complete.  I ordered the parts myself and finished it for $7k, saving $13k...

I did hire a guy to do the final connects, vacuum the system, and charge the refrigerant for $300.  It took me one day per floor to run the lines.  I plan on doing this for all of my rentals in the future.

Cleaning it requires a special kit they sell on Amazon and I just clean them once every two years.

[rothwem]

I installed a system in a house I built.  Upstairs had 4 indoor units paired up to the outside unit and downstairs had 3.  Professional company quoted me $10k per floor, acknowledging that working together me and the owner would take one day per floor to complete.  I ordered the parts myself and finished it for $7k, saving $13k...

I did hire a guy to do the final connects, vacuum the system, and charge the refrigerant for $300.  It took me one day per floor to run the lines.  I plan on doing this for all of my rentals in the future.

Cleaning it requires a special kit they sell on Amazon and I just clean them once every two years.

I think you're thinking about a mini split, not a mini-duct.  The mini-duct system uses an air handler and small 3" ducts so that it fits in places where normal ducts don't, but it still is not duct-less.