Zebra Instruments Masthead

Z•Tech•Tips #2

Remotely controlling the system from condenser

Every tech I know has dreamed about having some kind of remote-control device that he could use to turn the system fan on or off from the outside unit, without having to go inside the house or business. Our engineers are working on this idea, but we recently received a suggestion from Jim Heinz, of Heinz A/C and Heating in Palm Harbor, Florida that costs very little and doesn't have to be attached or removed from the system each time you arrive on the job.

Jim's suggestion:
"When we install new or retrofit air conditioning or heat pump systems, we tie the fan control wire, usually the green wire, to the condensing unit, and cap it off.  When setting up the system, or servicing it later, we attach the Zebra stat to the wiring at the condensing unit.  We can now control the system from outside including the evaporator fan.  We don't need to keep running inside to change the mode of the thermostat.  It is especially useful doing it this way when working on the roofs of high rise apartment buildings."

So, whenever you do new construction or retrofit a unit that requires replacing the wiring going to the condenser unit, consider adding a 'spare' wire or two. If the replacement unit isn't a heat pump system, add two wires: a red one for 'hot' and a green one for the fan control. Even with copper prices at an all-time high, an extra conductor in the line doesn't cost very much compared to the time you spend turning the system on and off from the inside.

An added bonus of Jim's idea is that you may be able to do some services on a system without actually having to have access to the inside of the home. Thanks for the suggestion, Jim.  ••z••

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