Are ducted mini-splits a better option than a standard A/C with heat pump and standard ducts?

I was looking at the Mitsubishi ducted systems but was wondering what, if any, advantages there are with a ducted mini-split?

I have been reading into them for a while and have learned there are many many many advantages.

-no ductloss because there are no ducts.
-precise control of each individual zone (mitsubishi I-see even scans the room to apply heat evenly)
-quiet function
-COPs approaching geo levels
-inverter driven compressors to ramp the speed with the load (traditional heat pumps have on/off, off/50%/100%, and several other variations.)
-low ambient operation (also a product of the inverter above since you can size for your lowest outdoor temp as 100% and the inverter adjusts you often dont need any backup electric heat)

Above to just name a few. I will be installing a ductless system in my addition. I had already purchased a flow center for geothermal and the ductless inverters made me decide to totally avoid geo. In fact, I plan on outfitting the rest of my house in the next couple of years and keep my old heat pumps as backup only. Also, dont forget that since these units are cutting edge they also have very high SEER ratings, much easier to install than traditional heat pumps (I am not going to miss the nitrogen and brazing) and have common sense approach to their design (the side mounted fan for example.) Almost everyone I have talked to has had nothing but good things to say about them. The people with bad things to say had years of working on older ductless systems made before inverters. In fact, after I installed my traditional heat pump, the contractor who I paid to fill it with R410 was talking about what a design marval some of the ductless systems were and how they came with enough refrigerant for several different lineset lengths. He said that the design of the things is amazing.

You did specify ducted mini-splits, not ductless. I've been looking at them lately, as I plan to order equipment soon. I was disappointed to see that the efficiencies are quite a bit lower for ducted versus ductless. Also, the Mitsubishi system that functions down to -13 F. seems to only be available in the ductless wall units. As a result, I have decided to go with full ductless with the ugly wall units.

Even the ducted systems should out-perform conventional A/C as long as the duct runs are kept short, and inside the conditioned envelope. I was going to mount them in a dropped ceiling over a central closet, and they wouldn't have had any added ducts above the unit itself, but I can't get the low temperature performance with that set-up. I don't want to sit around freezing during a record cold snap because I opted for a less efficient but aesthetically better looking system.

Posted By jdebree on 24 Dec 2013 07:52 AM
You did specify ducted mini-splits, not ductless. I've been looking at them lately, as I plan to order equipment soon. I was disappointed to see that the efficiencies are quite a bit lower for ducted versus ductless. Also, the Mitsubishi system that functions down to -13 F. seems to only be available in the ductless wall units. As a result, I have decided to go with full ductless with the ugly wall units.

Even the ducted systems should out-perform conventional A/C as long as the duct runs are kept short, and inside the conditioned envelope. I was going to mount them in a dropped ceiling over a central closet, and they wouldn't have had any added ducts above the unit itself, but I can't get the low temperature performance with that set-up. I don't want to sit around freezing during a record cold snap because I opted for a less efficient but aesthetically better looking system.

Yes, I was referring to DUCTED mini-splits. I know that the efficiency on the ducted would be lower than a ductless but I wanted to know is it better to go with a DUCTED mini-split or a standard A/C & Heat Pump setup ? What advantages are there with a ducted mini-split over a standard A/C with ducts?

I can cool/heat my first floor with 2 DUCTLESS mini-splits because of the open design/layout but the 2nd floor has more hallways/rooms and is less open therefore a ducted system would work better. Of course the ducts would be within conditioned space under a SIP roof attic. Very limited runs, under 30 feet.

Shorter, larger ducts increase efficiency and a simple but useful case is where a single mini-split head can also condition the room behind it. Preferably with an in-wall mount to avoid the aesthetic issue.

But at some point, it's just semantics.

Shoot I got the ducted turned around. Still you get all the other advantages but your efficiency drops to about 16seer. I would do very short runs and seal + insulate your runs. No flex unless you really need it. I would also get a small foam kit and use that to seal and insulate the runs. Check on the specs because I believe they all also run on a much higher flow and lower static pressure than normal units which means bigger ducts.

Just wondering , what is your beef with the ductless. The actual wall hung unit will be much smaller than the total supply and return duct size. If you don't like the look consider the ceiling unit since it is about the size of a normal return vent but looks better. My wife hated the units at first but since we have been looking at them has started to like them.

Posted By kogashuko on 24 Dec 2013 01:30 PM
Just wondering , what is your beef with the ductless. The actual wall hung unit will be much smaller than the total supply and return duct size. If you don't like the look consider the ceiling unit since it is about the size of a normal return vent but looks better. My wife hated the units at first but since we have been looking at them has started to like them.

I have no beef with ductless, I am actually getting 2 ductless units. The 2nd floor is not condusive to a ductless design.