Ductless Heat Pumps for rentals and personal residence?

[Jeff S.]

Just starting to research ductless heat pumps and wanting to get BP's take on what kind is best and some feedback. The properties are for: 1) 650 sf upstairs unit in a duplex; 2) 1650 sf ranch style (one level) and 3) 2400 sf ranch style. Portland OR temps range from 20 to 100 degree fahrenheit.

Most furnace people aren't that hot on them but replacing a new gas furnace AND a new air conditioner is huge (14K) when a ductless can run cheaper purchase wise (4k) and efficiency wise.

[Steve Abercrombie]

@Jeff S. - I'm up in Washington State (Olympia and Tacoma) so similar climate. I have a lot of experience with ductless mini-splits. I have one installed in my personal residence, am considering installing them in a rental duplex, and I have commissioned dozens of them in apartment and commercial projects in Puget Sound.

Overall I'm a huge fan of the units - they are pretty easy to install, work really well, and are energy savers compared to about any other system out there. They do have problems in other climates when the temp gets below the teens during the winter. The upside is that you get A/C for our increasingly hot summers. 

A few gotchas on these units:

• While installation is pretty easy - the refrigerant lines are soft copper. If the installer has to go around a corner, force the lines through a tight (or blind) penetration, or just isn't careful; they can kink or break the lines which leads to a host of problems that won't be covered under the mfg warranty.
• They don't heat enclosed bedrooms or bathrooms really well when the doors are closed. Plan to install cadets, heat panels / cove heaters, or baseboards in any room that is on an outside wall or has windows. Wiring and 220 circuit requirements can run the cost up quickly if you are converting from a central system. You can also run multi-head systems, which are great for comfort and convenience but expensive up-front. There are alternate options to transfer air to/from bedrooms, but those get somewhat complicated.
• The cassette fan coils are ugly and take up wall space, You also need a thermostat for each one so you have to plan for labor for that wiring.
• In my experience the Japanese products (mitsubishi, fujitsu, daikin, etc.) are better technology than the American manufacturers (trane, lenox, etc.). LG is somewhere in the middle.  If you are trying to install smart thermostats like a nest make sure that the unit you're buying is compatible. Most of the manufacturers you can only use their thermostat and their "smart" thermostats aren't typically that great.
• Pay attention to condensate (the water produced by the units inside and out). You've got to run a drain from the inside unit particularly. If they back up they can create a big headache
• You need to clean the filter on the inside unit more frequently than 60 days. If there are pets or a lot of dust you may need to do it more frequently. If you don't the fan has to work a lot harder and that will eventually shorten its life.
• If you are switching from a central system or get tripped up needing to comply with current code - you may have to provide a fresh air source (this is really good to do in any building, particularly your primary). Panasonic bathroom fans on constant low with an occupancy sensor or humidity sensor to boost into high speed are my go-to, but it is another potential cost add.

The utilities offer good incentives / rebates for ductless heat pumps, but you usually have to use a "registered installer" so you may end up paying more than the rebate is worth.