High quality heat pumps built by different manufacturers may have
almost identical performance and durability. However, a system's performance
can be greatly affected by the quality of the installation (proper sizing, the
duct system, and attention to detail). The low bid may not necessarily be the
best one. Heat Pump Sizing: There
are three major reasons that a heat pump should be properly sized for your
home. 2. Durability:
Most wear on a compressor occurs when it starts up. Oversized equipment cycles
on and off more often than properly sized equipment. 3. Efficiency:
Oversized equipment has shorter ON times, which means more time is spent
getting started - the part of the heat pump cycle where efficiencies are
relatively low. Duct Design: One of the
most important parts of proper installation is insuring that the ductwork can
deliver adequate air flow to maintain comfort in the house, and also meet
manufacturers' specifications. Dampers: After the
system is installed, the HVAC contractor should use dampers to "balance" the
system. Duct Sealing: Air
leakage from ducts can be one of the largest sources of heat loss in the home.
Ducts need to be sealed where sections are joined; along the seams in
individual duct sections, and where the duct penetrates from unheated to heated
locations. It is recommended that contractors use a blower door to test duct
tightness and mastic to seal leaks in the duct work. Duct Insulation: Where
metal ducts pass through unheated areas (garages, crawl spaces, and attics)
they should be insulated with a minimum of R-11 insulation. Flex Duct: If flex duct
is used, it should be installed with the following considerations: 2. Make all bends
gradual so that airflow is not restricted. 3. Seal connections
(aluminum duct tape) between flex and sheet metal ducts. Seal all joints with
sheet metal screws and mastic. 4. Support flex duct so
air flow is not restricted due to sagging. 5. Stretch the duct to
its full length so that air passages are as smooth as possible. Outdoor Unit Installation:
The outdoor unit should be installed on a concrete pad. If possible, locate the
unit so it is sheltered from prevailing winter winds and where the noise it
produces won't bother you or your neighbors. Service Contract: Regular
annual maintenance is critical for heat pump reliability.
1. Cost:
Larger equipment is more expensive than smaller equipment, if your system is
too large you'll spend too much for it. If your heat pump is undersized for
heating, supplemental heat will operate too much, increasing your electric
bill.
1. Use R-8 or
higher insulated flex duct.
