Launch Slideshow

Installing a Mini-Split Air-Source Heat Pump

Installing a Mini-Split Air-Source Heat Pump

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    JLC spent a day on the job in April with master plumbers Dave Ragsdale (left) and Chris Blaisdell (right), a two-man mini-split heat pump installation crew for ReVision Energy, based in Portland, Maine. The following images show the pair setting and connecting the outdoor compressor unit and the indoor fan unit for a Fujitsu mini-split capable of providing 12,000 Btu of heat energy during winter or a ton of cooling energy in summer at very high efficiencies.

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    Dave Ragsdale mortars a concrete masonry pedestal into position on the patio of an existing home near Portland, Maine. The outdoor unit of the Fujitsu mini-split heat pump system will be anchored to these masonry supports.

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    Dave Ragsdale and Chris Blaisdell set the outdoor unit of a Fujitsu Halcyon one-ton mini-split system onto masonry supports. Bolts drilled into the masonry will secure the unit in place. Typically, ReVision Energy installs the outdoor part of the heat pump onto a wall bracket or wooden stand next to the house, elevated at four feet so that the unit won’t be blocked by winter snow. But in this case, the sheltered location in the home’s rear entry alcove allows an installation close to ground level.

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    While Dave Ragsdale works on the outdoor unit of the system, Chris Blaisdell attaches a mounting bracket for the indoor side of the system to an interior wall.

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    Outside, Dave Ragsdale removes a protective housing from the outdoor unit of the mini-split system to gain access to the wiring connections for the system.

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    Inside the home’s basement, Chris Blaisdell pulls through the four lines that connect the indoor heating and cooling fan to the outdoor compressor: Two white refrigerant lines (one for vapor and one for liquid refrigerant); a black power and control electrical cable; and a clear condensate line.

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    Chris Blaisdell prepares to connect the system’s color-coded electrical power and control wires to the wall-mounted fan for the indoor unit of the heat pump.

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    Chris Blaisdell threads the refrigerant lines, condensate tubing, and wiring cable for the system through a hole drilled in the partition wall where the indoor fan unit for the system will mount.

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    Outside, Dave Ragsdale hooks refrigerant lines up to the outdoor compressor unit of the system. The unit comes pre-charged with R-410a refrigerant, but the refrigerant won’t be released into the copper lines until after the lines have passed a 600-pound overnight pressure test using compressed nitrogen.

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    Working in the home’s basement with a headlamp for light, Chris Blaisdell connects a refrigerant line for the indoor fan unit.

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    Dave Ragsdale charges the refrigerant tubing for the mini-split system with 600 pounds of compressed nitrogen. The crew will leave the system pressurized with nitrogen overnight to test for leaks before charging the system with refrigerant the next day.

"Mini-split" air-source heat pumps are establishing a strong foothold in northern states, based on the advancing capability of heat pump technology. The newest generation of mini-splits boasts cooling efficiencies of SEER 25 and better, with heating coefficient of performance (COP) ratings near 3 (meaning the equipment can supply heat equivalent to three times the electric power it consumes). Better yet, the latest equipment can heat homes even as outdoor temperatures plunge below zero, making heat pumps viable as the sole heat source for a well-insulated house — even through a harsh Northern winter.

JLC visited a jobsite in Maine in April to see technicians from Portland-based ReVision Energy install a system in an existing home, where the unit will "unload" the home's existing oil boiler during much of the year, limiting the boiler's heating role to the coldest part of the season when the heating demand is greatest (which is also the period when the boiler will operate at its highest efficiency). During swing seasons, the heat pump will take over much of the home's heating requirement — an effective use of the heat pump, which operates most efficiently when its outdoor-air heat source is relatively warm.

The heat pump system shown here, a Fujitsu Halcyon AOU12RLS2, retails online for about $1,600 (not counting professional installation), and is rated at 12,000 Btu for heating. When outdoor temperatures drop below 20°F, the heating capacity decreases. But the unit can still supply some heat at outdoor temperatures of -5°F. The system comes with outdoor unit containing the compressor, controls, and a reserve tank containing enough R-410a refrigerant to charge 49 feet of refrigerant lines as well as the wall-mounted indoor unit's heating and cooling coil.

Four lines connect the indoor unit to the outdoor unit: two refrigerant lines (one for liquid coolant and one for vapor); a power line for the indoor unit's fan; and a condensate line that drains any water vapor that may condense on the indoor unit's coil when the system is operating in cooling mode.

A system like this takes the crew one or two days to install, including the wiring and refrigerant line installation. The two technicians shown in this slideshow are master plumbers with additional training in refrigeration technology. They also have the skill to run the rough wiring for the system, but a licensed electrician will be needed to inspect the installation and hook up to the home's electrical panel.