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Ductless Heat Pumps – A New Option for Home Heating

The ductless heat pump is an exciting option for home
heating that offers

• Efficient operation at outside temperatures of
17°F. and below without electric backup

• Quiet operation – both indoors and outdoors

• Heating and cooling

• Simplified installation

Ductless heat pumps are appropriate for both
replacement of existing heating systems, especially
baseboard/wall heaters, as well as for new
construction. Ductless heat pumps have been
installed in commercial buildings for more than 20
years and are available from many manufacturers.

Ductless heat pumps are very efficient for several
reasons: Since the heated or cooled air is delivered
directly to the room, ductless heat pumps avoid
efficiency losses associated with ductwork –
typically 15-20 percent. Variable speed compressor
models, usually labeled “inverter technology,” avoid
on-off cycling losses and are able to provide usable
heat efficiency on all but very cold days. And,
because they provide heat/cooling to specific areas
of the house, they can be more efficient since each
“zone” can be heated to the desired temperature.

Ductless heat pumps are sometimes called a “minisplit”
heat pump* and consist of an outside
compressor unit and one or more inside “heads” that
deliver conditioned air to the room or rooms. Inside
units are typically mounted high on the wall, but
certain models can be recessed in the ceiling or even
installed with a short duct run to serve adjacent
rooms. The inside and outside units are connected by
refrigerant lines, usually concealed in the walls or
ceilings or under a cover on the outside of the house.
Some models allow several indoor heads to be
connected to a single outside compressor.

Ductless heat pumps operate on the same principle
as traditional heat pumps - using electricity to move
heat between outdoor and indoor air by compressing
and expanding a refrigerant. Most new ductless heat
pumps use the newer, less environmentally-harmful
refrigerant R-410a. Depending on the rated capacity,
they require 110 or 220 volt AC power.

*So-called “mini-split” because they tend to be smaller capacity
(BTU/hour “tonnage” rating) and because they are “split system”
with separate compressor (outside) and expansion heat delivery
unit (inside) units, similar to traditional heat pumps, but unlike a
through-the-wall unit, sometimes used to heat motel rooms.

A very quiet oscillating fan delivers conditioned air
more evenly to all parts of the room. The indoor
temperature and other settings, such as automatic
night temperature setback are set with a hand-held
remote control. Like any air conditioner in cooling
mode they provide some dehumidification of the
indoor air.

Applications for Ductless Heat Pumps

Ductless heat pumps are most appropriate for homes
with open floor plans, since each indoor “head” can
serve the entire “zone” not blocked by doorways.
Some typical applications for ductless pumps

Replacing an existing zonal heating system –
Ductless heat pumps can replace existing electric
baseboard/wall units, woodstoves. A cost effective
electric heat conversion in a small house might
consist of single system serving the main area of the
house, leaving existing electric baseboards in
bedrooms and bathrooms.

Room additions – Another application for ductless
heat pumps is when a room is added to a house or an
attic is converted to living space. Rather than
extending the home’s existing ductwork or pipes or
adding electric resistance heaters, the ductless heat
pump can provide efficient heating and cooling.

New construction –New homes can be designed or
adapted to take advantage of the characteristics of
ductless heat pumps. Typically one or more systems
might be installed in various “zones” of the house to
simplify installation and minimize refrigerant line

Installation considerations for DuctlessHeat Pumps

Several options may be considered when installing a
ducted heat pump in homes:

• Multi-zone with one outside compressor unit
serving several indoor units

• Two separate single zone systems may be
less expensive and easier to install than a
multi-zone system, particularly if long runs
of refrigerant lines are required for one or
more indoor units

Properly sizing the system to the heating/cooling
loads of the house is important, but not as critical as
with traditional single speed heat pumps, since
variable speed compressor allows ductless heat
pumps to operate efficiently in “part load”

The inside and outside units should be located to
minimize refrigerant piping runs (typically less than
50 ft. unless special measures are taken). Because
the outside unit is considerably quieter than
traditional heat pumps, installers have somewhat
greater flexibility in deciding where to locate the
compressor to keep refrigerant line lengths as short
as possible.

Some people are concerned that the wall-mounted
unit will be an “eyesore” in the room, but most
report after a few weeks they forget they’re there.
Indoor units can be painted if desired. Indoor units
are usually powered by the outside unit and do not
require separate electrical connection. Because these
units dehumidify the air in the summer, they require
a small condensate drain line from the indoor unit to
the outside.

Indoor and outdoor units are connected by two
refrigerant lines and an electrical cable. Each model
has a maximum distance and height difference
between inside and outside units that must be
observed. A technician familiar with high pressure
R-410a refrigerant is needed to insure the systems
are installed and “commissioned” at the initial start

For More Information on Equipment, click here

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