Monday, September 19, 2011

How to Add a Duty cycle to a Fan in a Central A/C System ?

My central air conditioning system fan is wired so that when the thermostat is in the %26quot;on%26quot; position the fan runs, whether or not the compressor runs. The thermostat is a line voltage 220 Volt unit (honeywell DT70 model) . I would like to change the thermostat so as to have the fan only run when there is a need for cooling. Can anyone make a suggestion as to the type of thermostat that I should use ? thanks.How to Add a Duty cycle to a Fan in a Central A/C System ?You need to rewire the fan in series with the A/C compressor adding a time delay so both do'nt come on at the same time %26amp; draw too many amps on startup. A one minute delay would be fine on the fan side, giving the compressor enough time to %26quot;level out%26quot; to it's running amperage, but not enough time to freeze the evaporator coil. Basically what will happen in that configuration is that when the t-stat calls, the compressor will be energized %26amp; start running. In turn the time delay to the fan will be energized at the same time, %26amp; complete the circut to the fan a minute later, when the t-stat is satisfied, both will shut off at the same time.

Hope this helped you, good luck!!