How to Zone a Forced-Air Furnace and Air Conditioner
Ask This Old House plumbing and heating expert Richard Trethewey shows how to divide a home's heating and air-conditioning system into different zones
In this video, Ask This Old House plumbing and heating expert Richard Trethewey shows how to divide a home's heating and air-conditioning system into different zones.
1. Cut into each flexible branch duct and install a motorized zone damper. Secure the damper to the duct with nylon cable ties.
2. Make the wire connections at each motorized damper and run all the wires back to the control panel at the furnace.
3. Remove the control panel's cover and plug in the telephone-jack connections for each zone.
4. To maintain the proper pressure within the system, install a weighted bypass damper between the supply trunk and return trunk.
5. Seal all the duct joints with mastic or foil-faced duct tape.
6. Adjust the weights on the bypass damper to ensure proper airflow to all registers.
7. Find a suitable spot in the house to install a wireless thermostat to control the new zones. To ensure accurate readings, place the thermostat away from direct sunlight and heating registers.