Ductless: 3 head system or ductless with ducts to 3 bedrooms?

11 years ago

What would you do and why?
I am about to embark on a major remodel. Our house is electric only (baseboards and on the main level, a 2 head ductless heatpump put in in 2009). Our upstairs will end up around 850-900sq ft with 3 bedrooms. Originally, I thought we'd just put in a 3 head ductless system. Then, one salesperson (and only 1) said, why not a single unit with blower and air return and ducts to the 3 bedrooms? I said I didn't know, so he explained the system.

It seems it will be a little bit less $ to install this type of system and you don't have the (unsightly) heads in each bedroom. Disadvantages are regular filter replacement for the air return and needing to all have the same temperature in the bedrooms (rather than each bedroom having their own remote/control of temperature).

Ducts are "insulated and sealed, and with a vapor barrier", but otherwise would be in unconditioned space. Is the "insulation" on a duct sufficient?

What would you experts choose? The ducts are appealing right now (cost savings). Are they a cost savings in the long run? Our current 2 head LG system has been running great since 2009 with very little/no maintenance (filter cleaning only). What should I expect with a ducted ductless system?

More about us/our climate--we live outside of Seattle. When we put in the ductless system for our main living area in 2009, we were among the first residential users. They tracked our electrical usage, etc, to do research on their effectiveness in our area. They told us not to take out our wall electric baseboards, because we'd need them for supplemental heat, etc. Well, despite some very cold weeks the last couple of years (unusually long with snow on ground), we've rarely had to use supplemental heat from the baseboards. We do have a wood burning fireplace (which I'd like to get a wood stove insert for and get more efficient) which could also be a back up heat source. I'd like to get rid of the wall-consuming baseboard heaters.

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Comments (4)

ionized_gw
11 years ago
Ductless mini split or ducted mini split. In addition to the trade-offs that you mentioned, the controls might be better for one option or the other and one brand over another. With my Mitsubishi multi, mini splits, I can not set a true set-back. The remotes are only capable of timed on and off.

Filter service will be easier with the ducted system. You will have one filter to deal with. Do your LG heat pumps have electric heaters? IIRC, one brand does, maybe Sanyo or Toshiba.

I don't know what to tell you about the baseboard heat. You probably have as much experience as anyone using the mini split system. If you put in a ducted system, they can put electric heaters in that, but I don't know if that will coordinate well with the manufacturer's thermostat.

Ducts result in duct losses, no doubt. You have some heat transfer and they leak right off the bat. The leaks only get worse over time so they need some work now and then and no one ever does that.

Do you have a local air supply for the fireplace? Otherwise, they are a huge heat hog sucking warm air out of the house.
kirkhall
Original Author
11 years ago
Thanks ionized.
I know my fireplace is a negative heat "source" right now. One of the reason I'm looking into converting it to a wood stove insert style. Our LGs don't have a built in electric heater.

I've been told by one salesman, from a different company, that the Mitsubishi system with ducts can't do ducts longer than about 6 feet. The one trying to sell me on this as a good alternative says (the other guy) just doesn't have enough experience. And, sees no issues. So, since I really only have these 2 guys from 2 different companies...I'm trying to figure out "who is right".

Anyone with any experience with these? Other salespeople?
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ionized_gw
11 years ago
I don't know about the duct length for Mitsubishi or the others. That can probably be calculated from the pressure/flow date here, but I don't know how to do it.

http://www.mitsubishipro.com/media/289434/sez-kd09na-suz-ka09na_submittal.pdf
kirkhall
Original Author
11 years ago
Hmm. Yeah, I am not sure how to do that either. I asked the company that is sure it will work to provide some references of people they've done it for. I'll be meeting with one person next week (who is new to this system) to observe how it works.

I'll report back on that visit; as well as if we do end up going this route, how it is working for us.

The company offers a 2 yr satisfaction guarantee so if we don't like it, I suppose we can go back to what we had planned on in the first place.