Bell & Gossett Comfort-Trol Zone Valves are opened by a heat motor. Because of this, there is about a two-minute period between the time the thermostat closes (calling for heat) and the time the Comfort-Trol opens. As long as heat is required, the Comfort-Trol is kept in the open position by a built-in control switch, which meters small amounts of electricity to the heat motor. When the thermostat opens (signaling the need for heat has been satisfied), a return spring in the Comfort-Trol slowly closes the Comfort-Trol zone valve.
Heating Valves and Zone Valves can be found at www.supplyhouse.com
