Ductless mini-split heat pumps

Ductless heat pumps - or mini-split heat pumps - are excellent for zone space heating and cooling strategies. Or for room additions, small apartments and homes with faulty ductwork or no ductwork at all... They belong to the air-source heat pumps family.

Ductless heat pumps are in direct competition with ductless air conditioners. Their advantage is that they are also heating units, with a higher energy-efficiency in heating mode.

The technology

Like central air-source heat pump units, ductless heat pumps also have an indoor air-handling unit and an outdoor compressor and condenser part.

But instead of ductwork, ductless heat pumps use a conduit to link the outdoor and indoor units. That conduit houses the power cable, suction tubing and refrigerant tubing and transfers heat or cool between outdoor and indoor air, using electricity to compress and expand the refrigerant (in the conduits).

Less energy losses and lower Running costs

Because mini-split heat pumps do not rely on ductwork, they aren't subject to the losses of ducted systems (often estimated at 30%).

Since heating and cooling is restricted to a specific part of the house or a room(s), with a proper use and design they provide lower running costs and energy savings.

Ductless Heat Pumps advantages

Ductless heat pumps can have up to four indoor air units connected to the same outdoor unit, each one with its own thermostat. And they allow extreme flexibility with their floor-standing, ceiling-suspending and wall-hanging models…

Installation is also easy; three-inch small holes for the conduits are the norm. And since conduits come in varying lengths, the outdoor units can be located (or hidden) on the most convenient site, often in the side or back of the building.

Ductless Heat Pumps Disadvantages

Like other air-source heat-pumps, ductless heat pumps aren't efficient enough on heating mode in freezing temperatures. Whenever temperatures fall below 34ºC/4ºC their efficiency becomes too low.

Ductless Heat pumps Costs

Prices of ductless heat pumps are falling. A 12,000 BTU (a ton...) ductless mini-split wall-mount heat pump with a 17 SEER may cost you something between $900-$1,200.

Sites like Amazon are offering ductless heat pumps with lower SEERs at very low prices. See for instance 12000 btu 13 SEER mini split ductless a/c air conditioner & heat pump 115V / 60Hz with free installation kit.

Anyway, final prices depend upon the configuration and the number of zones covered by each unit.

Installation

It's easy to install a ductless heat pump. But oversized units and incorrectly located air-handlers are common causes of low-inefficiency, large swings in temperatures and improper control of humidity.

Warranties

Warranties of one year for indoor units and 3-6 years for compressors are common.