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Thread: HRV Turns on AC

  1. #1
    Join Date
    Feb 2012
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    HRV Turns on AC

    How can I prevent my HRV from turning on the Air condtioner?

    The HRV has a relay to turn on the furnace fan. The N/O contact is wired to the furnace conrtrol board on the Red (24 Vac) and Green (Fan). This works well.

    The thermostat is also wired to these furnace contacts along with a yellow wire for the A/C.

    When the HRV energizes the Green to turn the furnace fan on, the thermostat also energizes the yellow / AC.

    Do I need an additional relay to prevent the HRV from turning on the A/C?

  2. #2
    Join Date
    May 2000
    Indianapolis, IN, USA
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    Often when you put voltage to G, it feeds back through the stat to Y. Someone with electrical control knowledge needs to study the HRV wiring and come up with a solution.

  3. #3
    Join Date
    Jul 2004
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    Like baldy said, often the t-stat has a common terminal for Y + G. This is most common on the older t-stats. It'll take someone on scene who knows wiring to get it right and it may require more controls than what you already have. Or not, depending on different wiring options.
    If YOU want change, YOU have to first change.

    If you are waiting for the 'other guy' to change first, just remember, you're the 'other guy's' other guy. To continue to expect real change when you keep acting the same way as always, is folly. Won't happen. Real change will only happen when a majority of the people change the way they vote!

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