Mix and Match HVAC

Discussion in 'The Projects Forum' started by SolarFun, Oct 16, 2009.

  1. SolarFun

    Thread Starter New Member

    Oct 16, 2009
    16
    0
    I just bought an oldish condo which is hot water heated and has been retrofitted with AC. I want to install a single programmable thermostat in place of the individual mechanical thermostats for heating and cooling. The heated water valve is turned off WITH current (24VAC) and on with NO current. All common programmable thermostats want to turn it on WITH current and off with NO current. I have used the AC terminal (terminal Y) on a programmable thermostat to regulate heating successfully, pretending it's really cooling. However, this takes up the Y terminal on the thermostat, making it impossible to operate the AC.
    Is there a way to reverse the current flow to the water actuator valve without spending a bundle? That is, when my thermostat switches on the current to activate the heater, I want the heater valve actuator to see no current, thus turning on and vice versa. This is a long explanation to explain a rather simple request so I hope that it's understandable.
     
  2. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    You could add a relay to the system to invert the logic.
     
  3. SolarFun

    Thread Starter New Member

    Oct 16, 2009
    16
    0
    I have used relays to power on one circuit by powering on another. I can buy a relay that does the opposite? Any advice as to where I would buy one?
     
  4. CDRIVE

    Senior Member

    Jul 1, 2008
    2,223
    99
    Radio Shack sells many relays the contain a common pole with both normally open and normally closed contacts. They would be SPDT(1 pole) & DPDT (2 poles) relays. Some are 3PDT (3 poles)and 4PDT (4 poles).
     
  5. SolarFun

    Thread Starter New Member

    Oct 16, 2009
    16
    0
    Thanks, I'll get one.

    Larry
     
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