Checklist: HVAC

By Maggie Leslie on 03/22/2010

A home can be heated or cooled using electricity, gas, geothermal energy, solar energy or a combination of energy sources. Radiant floor-heating systems are an inherently efficient way to heat, since there is no heat lost through ductwork, but a forced-air heating system can also be a very efficient option if designed and installed properly. The items on this checklist should be considered when installing any type of ducted system.

A clean start: Sealed crawlspaces are one effective method for getting HVAC equipment into the conditioned space. photo courtesy of Home Energy Partners 
photo courtesy of Home Energy Partners<

First off, a room-by-room Manual J heat-loss/heat-gain calculation must be completed. The maximum-oversizing limit for air conditioners and heat pumps is 15 percent. Adhering to the maximum-oversizing limit both ensures that you are not paying for more capacity than you need and that the system will properly dehumidify the home and run efficiently.

• Heat pumps and air conditioners have a Seasonal Energy Efficiency Ratio rating of at least 14 SEER and a Heating Season Performance Factor of at least 7 HSPF. Gas furnaces used for either primary heat or backup heat have a rating of at least 90 Annual Fuel Utilization Efficiency.
• Ductwork and the mechanical unit are located in the conditioned space, if possible. All ductwork has an insulating value of R-8.
• Use rigid-metal ductwork for increased durability and indoor-air quality. Rigid metal is easy to clean, and will not trap dust or absorb moisture.
• Building cavities, such as floor joists, are not used as part of the forced-air supply or return system.
• All joints/seams in the air-distribution system are sealed using fiberglass mesh tape and duct mastic; this includes duct connection to metal boots (in subfloor), trunk lines and air-handler units. The insulating liner of the ducts is also sealed with mastic.

• Indoor and outdoor HVAC units are matched according to the Air-Conditioning & Refrigeration Institute Directory or the manufacturer’s listing.
• The correct charge of refrigerant has been installed per the manufacturer’s specifications.
• Registers and diffusers have proper throw and spread to keep rooms properly conditioned as the load specifies.
• Duct dampers are installed and accessible on supply vents. The dampers make it possible to adjust the flow and spread of air from the registers.

• Ducts are sealed and tested by a Home Energy Rater to have no more than 5 percent leakage.

• If installing a heat pump, an outdoor thermostat is installed to control when the electric heat strip’s power is on. This will maximize your efficiency.
• programmable thermostat is installed.

Sources for this checklist include Advanced Energy System Vision Guidelines, Southface Energy Institute Technical Bulletins, HealthyBuilt Homes program guidelines and Energy Star guidelines for homes and indoor quality.

Maggie Leslie is program director of the WNC Green Building Council. She can be reached atmaggie@wncgbc.org or at (828) 254-1995.