This unit should go in a shaded location outside the house where it can have at least 4 inches of clearance behind it and 20 inches of clearance above it and in front of it. The 119-pound unit can be mounted on brackets fastened to the wall, as shown, or bolted to concrete blocks resting on the ground. Locate the Air Handler It mounts on an exterior wall no more than 33 feet from the outdoor unit, at least 2⅛ inches below the ceiling and 3 feet from a TV. First, the mounting plate is screwed to the studs, as shown. At the plate's lower-right corner, the installer drills through the wall with a 3-inch hole saw. Outside, a connecting hole is drilled ¼ inch below the one inside. Mount the Air Handler With the cover off, the control wire, refrigerant lines, and condensate drain hose are attached to the unit and taped together, and a protective sleeve is fitted into the hole in the wall. The unit is hoisted up without its fins being touched, and the taped parts are fed through the sleeve, as shown.

The unit then mounts to the plate. Set Up the Condenser The outdoor unit is connected to the control wire from the indoor unit and to a jacketed power cable leading to the breaker panel. Then the ends of the refrigerant lines are fastened to the condenser with flare nuts, as shown. Flare nuts are also used to join these lines to the ones on the indoor unit. A plastic channel screwed to the siding hides the lines, condensate hose, and control wire. After the hose is checked to make sure it drains freely, the end of the hole sleeve is sealed with silicone to prevent water infiltration. Then the channel is capped, as shown. A gauge manifold and a vacuum pump are hooked up to the refrigerant lines to detect leaks and dry the lines as refrigerant is pumped into them. The last step is to put the cover on the air handler, as shown. The system is then ready to heat and cool. Last week, (EVER rater and Green Curmudgeon) Carl Seville and I took a trip up to Suwannee, Georgia to visit the Mitsubishi HVAC facility and learn more about their ductless heat pumps.

I've mentioned here before that when I get a chance to build a house for myself again, I'd like to eliminate the ducts by using ductless mini-split heat pumps, and Mitsubishi is one of the top brands. Here's why I want to go ductless: Duct systems can be done right but almost never are, thus robbing the heating and cooling system of its effectiveness and efficiency. Duct systems take up a lot of space in attics, basements, and other parts of the house. HVAC technicians don't understand - and often don't care about - ducts. Mini-splits are some of the most efficient systems (up to 26 SEER). Mini-splits come in smaller sizes and can better match the heating and cooling loads in the house. Mitsubishi's line of residential ductless heat pumps is called the Mr. Slim. It's a split system heat pump, which means that the compressor and condensing coil are outdoors, and the evaporator coil and blower are indoors. In that regard, it's like your typical 'central' air conditioner or heat pump.

You can tell if a house has a mini-split by looking at the outdoor condensing unit (photo right). They're thinner and smaller than the typical ducted system condensing unit. The indoor unit can be mounted on a wall, set into the ceiling, or sit on the floor. fan coil unit componentsAt the Mitsubishi facility, we saw all three styles, and you can see photos of them below.ac unit thermostat wiring Wall mount (set off from the wall here but mounted flush in a home)york furnace ac unit Floor mount (can be recessed into the wall) In addition to coming in smaller sizes (down to 6000 Btu/hour, half the minimum size of regular system), mini-split heat pumps can modulate the amount of heating or cooling through variable refrigerant flow (VRF) to match the actual loads in the house, not just the design loads.

They're also ideal for zoning a house and limiting the amount of energy you use for heating and cooling. The knock against mini-splits is that some people find them unattractive. They don't want to have that piece of equipment on their wall, even if it is quiet. Ceiling cassettes are a good alternative. Ducted mini-splits are another, and they allow you to hide the head above a dropped ceiling, for example, and run short ducts for the return and supply air. Another drawback is that even 6000 Btu/hour is too large for a high performance home that's going to have several heads (the indoor unit). The reason that Mitsubishi does this seems to be for ease of manufacturing. They make as few different evaporator coil sizes as possible. Even with these weaknesses, the ductless mini-split heat pump is a great idea and, I believe, will increase in popularity because of the many advantages. There's a ductless heat pump project in the Pacific Northwest that promotes and tracks the installation of these systems.

I heard about this from Bruce Manclark at the recent ACI conference in San Francisco, and he said they've got a 98% customer satisfaction rate through about 10,000 installations.Is a ductless mini-split heat pump in your future? Or are you gonna stick with this? Ductless mini-split systems consist of a compact indoor wall or ceiling mounted unit that delivers a controlled flow of conditioned air into the area (zone) that you want when you want. Mini-split energy-efficient "spot" heating and cooling has been popular in Europe and Japan for decades. Now mini-split air conditioners are becoming one of the most in-demand home appliances in the US. By automatically adjusting the speed of the compressor to match the heating or cooling requirements of the room, ductless air conditioners and ductless air conditioner heat pumps eliminate hot and cold temperature swings experienced with standard on and off systems. Easy, duct-free installation makes mini-splits ideal for home renovations or a way to supplement your centralized ducted system.

Designed specifically to meet the heavy traffic demands of public spaces, offices or restaurants, commercial mini-split systems are available with ducting. This option enables distribution of conditioned air to more than one zone and fresh air intake from outside. DC inverter technology, a signature trait of mini splits, drives their high energy efficiency and low noise operation. Convenient features like memory, auto-restart, programmability and dedicated dehumidification are often standard as well. They are available as cooling-only units or heat pumps. Ductless mini-split air conditioner heat pumps with inverter technology provide air conditioning and heating and use up to 49% less energy compared to standard heating or cooling systems. The sleek and stylish indoor units can be mounted low or mid-height on a wall, flat against the ceiling or recessed in the ceiling. Outside units are also compact and can be installed on the ground or wall mounted. For custom control of multiple zones, up to five indoor units can be matched with one outdoor unit.