Evaluating Contractors and Bids

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.

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.

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:

1. Use R-8 or higher insulated flex duct.

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.