Ductless AC?heat pump units

I have been getting questions lately on efficiency work about the pros and cons of ductless ac/heat pump systems such as the Mitsubishi Mr. Slim for use in select applications in the Dallas area.

On the surface, it seems like a good idea for some applications around here to provide conditioning for smaller areas with less power usage than traditional systems. I have even thought about it for my house in the master bedroom area.

In some brief research online I have seen some decension about these. Are there any particular downsides to the use of these systems in the southern climates?

I do not believe so. I have been in Southern China and Taiwan where they are used extensively to good effect. Just be sure to size them correctly.

I agree. I’ve used these in commercial applications all around the world (Philippines, Argentina, Mexico, etc) many times with great success. What did you hear were the downsides? They are simply small split systems, nothing more. What are you seeing as SEER numbers for the ones you’ve investigated?

Every time I see one of these units, I find them to be very effective. They won’t condition a whole house, but they work great in big rooms.


Have you talked to a local HVAC tech?

If not contact AirMechanix Bobbi Pappas 214-394-5520

Daikin is distributed out of Carrollton, 16 SEER and just announced tax credit program participation if this helps.

Also seeing more of these in the MB of lager homes…

Thanks for the replies.

The comments I saw seemed to come from HVAC type guys and were mainly about humidity issues. As Michael said, these seem to be used extensively in places with worse humidity than Dallas.

Just doing a few quick searches shoulded units anywhere from 13 to 23 seer.


No haven’t talked to any HVAC guys about them yet. I have seen a few installed. There is one in a house down the street - need to go knock on their door and ask about it. I think it would work great in my house in the master bedroom. Would allow us to cool down the bedroom at night without cooling the whole downstairs. With our design the master supply ductwork is terrible because of the run length. I think it really should have been a seperate unit, but you wouldn’t get that at this level or builder.

In my area (maui) its about 50/50 between ducted and ductless. The biggest difference between the two that I have notinced is air filtration. The ductless has very limited filtration options and in most instants appears inadequate. What I find alot is condensation tends to build up on the supply vents and louvers, then dust/debris starts to collect on the condensation and eventually mold/mildew. I find this 9 out 10 times with the ductless ac’s in the more humid parts of the island.


They are great for what you are asking about. They are very quiet and no problem to install in post construction apps.

They are very quiet (in and out) and can even run in the winter time if needed for high load applications.

They cost $$.

They are fractional HP so they can handle the common addition or finished basement requirements. Under-size the unit for dehumidification application.

Have any more questions, call.