Multiple triggers for HVAC fan?

Discussion in 'HVAC Heating & Cooling' started by DeweyBeach, Aug 30, 2010.

  1. DeweyBeach

    DeweyBeach New Member

    Dec 14, 2008
    District of Columbia
    We have a 2H/2C Honeywell FocusPro 5000 thermostat in our home and it works great most of the time at controlling the temperature. However, our kitchen has several large greenhouse windows, and when the sun is at a certain angle, the solar heat makes the kitchen about 10 degrees hotter than the rest of the house. The existing thermostat doesn't notice this temperature differential because it's located in a different room (near the return duct).

    The way we've always dealt with the hot kitchen has been to go to the thermostat and manually flip the HVAC fan to "on" as this moves the hot air from the kitchen (and presumably, draws it toward the thermostat, which then realizes that the compressor needs to come on to dissipate the heat).

    My question: would it be possible to mount a second basic thermostat in the kitchen that would trigger just the HVAC fan to come on when the kitchen temperature reached a certain level? I'm assuming this is possible as we have a steam humidifier on the furnace that basically does the same thing (turns just the HVAC fan on when steam is being produced). Any tips or tricks on making this work?

  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    If you used the fan line as the switched line, it should work. You'd need the 24vac supply line on one terminal, and the fan line on the other and run the thermostat in the cooling mode. Then, when the room got hot, it would connect the 24vac to the fan control line, and turn on the fan.
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  4. Thatguy

    Thatguy Homeowner

    Aug 27, 2008
    A bounty hunter like in "Raising Arizona"
    You can run any number of t'stats in wired in parallel so that a high temp [=closed contacts] on any of them would run the fan. It's called a wired-OR setup.
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