INSTALLING A NEW HEAT PUMP

A heat pump's performance and energy efficiency not only depend on the selection and planning of the equipment but also on careful installation.

Consumers and home builders alike tend to accept the lowest bid for heating and air-conditioning work. This unfortunate choice can often leave a system lacking 10 to 30 percent in the materials and labor necessary to optimize heat-pump performance. Rather than just accepting the lowest bid, it's best to research the performance records of local contractors, and get involved in the planning and decision-making about your new heat pump system.

You can avoid most of the common comfort and performance problems from improper installation by following these guidelines:

• Make your home as energy-efficient as you can with proper insulation, energy-efficient windows, and an effective air barrier, etc. Then your contractor can install a smaller pump system with shorter duct lengths. In an energy-efficient home, it isn't necessary to run ducts all the way out to exterior walls to install registers near the exterior walls.
• Install the ducts inside your home's insulation and air barrier, if possible. Research shows that this strategy is a major energy saver.
• Insulate your ducts to R-8 if they must be located in an attic or crawl space beyond the home's air barrier and insulation.
• Locate the outdoor unit on the north side of your home if possible. If not, pick a shady spot. There should be no obstructions within 10 feet of the sides with openings and the top.
• Specify that the measured air leakage through your new ducts be less than 10 percent of your system's airflow. Air leakage of 5 percent or less is possible with careful workmanship.
• Tell your contractor that you want a return register in every room.
• Don't use building cavities as ducts. Building-cavity return ducts are notoriously leaky and often cause comfort, energy, and moisture problems.
• Pull on ductwork after installation to make sure it is fastened and sealed well. (Seal duct joints with mastic.)

Installation and Location of Air Conditioners
If your air conditioner is installed correctly, or if major installation problems are found and fixed, it will perform efficiently for years with only minor routine maintenance. However, many air conditioners are not installed correctly. As an unfortunate result, modern energy-efficient air conditioners can perform almost as poorly as older inefficient models.

Be sure that your contractor performs the following procedures when installing a new central air conditioning system:

• allows adequate indoor space for the installation, maintenance, and repair of the new system, and installs an access door in the furnace or duct to provide a way to clean the evaporator coil.
• uses a duct-sizing methodology such as the Air Conditioning Contractors of America (ACCA) Manual D.
• ensures there are enough supply registers to deliver cool air and enough return air registers to carry warm house air back to the air conditioner.
• installs duct work within the conditioned space, not in the attic, wherever possible.
• seals all ducts with duct mastic and heavily insulates attic ducts.
• locates the condensing unit where its noise will not keep you or your neighbors awake at night, if possible.
• places the condensing unit in a shady spot, if possible, which can reduce your air conditioning costs by 1% to 2%.
• verifies that the newly installed air conditioner has the exact refrigerant charge and air flow rate specified by the manufacturer.
• locates the thermostat away from heat sources, such as windows, or supply registers.

If you are replacing an older or failed split system, be sure that the evaporator coil is replaced with a new one that exactly matches the condenser coil in the new condensing unit. (The air conditioner's efficiency will likely not improve if the existing evaporator coil is left in place; in fact, the old coil could cause the new compressor to fail prematurely.)

If you install a new room air conditioner, try to:

• locate the air conditioner in a window or wall area near the center of the room and on the shadiest side of the house.
• minimize air leakage by fitting the room air conditioner snugly into its opening and sealing gaps with a foam weatherstripping material.

Paying attention to your air conditioning system saves you money and reduces environmental pollution. Notice whether your existing system is running properly, and maintain it regularly. Or, if you need to purchase a new air conditioner, be sure it is sized and installed correctly and has a good EER or SEER rating.