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    Relay control of Attic Fan

    A contractor installed an attic fan for my this summer. I neglected to request a fan that had humidy sensor as well as a temp sensor. I could add the humidity controller, but they cost almost than the actual fan! I decided to use x10 fixture relay mod which I had in the parts bin. I used my weather data to control the fan. It work great for a week. Now the fan will NOT turn off. X10 signal is still strong. I am thnking I fried the module. I wired it in parrell is the fans temp controller. Was this a mistake??? I can not get back up to the attic yet because the access panel is in a closet that is now full of clothes again.
    Larry

    #2
    Those fans have a tremendous startup current. Likely you fused the relay. I'm not sure if they make an X10 module big enough. How many horses on that motor?

    Jon


    Originally posted by lpcalcaterra
    A contractor installed an attic fan for my this summer. I neglected to request a fan that had humidy sensor as well as a temp sensor. I could add the humidity controller, but they cost almost than the actual fan! I decided to use x10 fixture relay mod which I had in the parts bin. I used my weather data to control the fan. It work great for a week. Now the fan will NOT turn off. X10 signal is still strong. I am thnking I fried the module. I wired it in parrell is the fans temp controller. Was this a mistake??? I can not get back up to the attic yet because the access panel is in a closet that is now full of clothes again.
    Jon Ort
    JonOrt@The--Orts.com
    (Remove the dashes in the address, spam is getting out of hand)

    Comment


      #3
      Originally posted by Oman
      How many horses on that motor?
      Jon
      Not to sure about that. It was a HomeDepot "special". The unit is not
      that large - CFM 1320. No info on HP. The relay mod that I used was rated at 15A. Is that not enough?
      Larry

      Comment


        #4
        Originally posted by Oman
        Likely you fused the relay. I'm not sure if they make an X10 module big enough.
        Jon
        You got it!. Relay is fused.

        Before I fuse another fixture mod.... can I hack the module & install a "better" relay.

        What are my other options to control this attic fan?
        Larry

        Comment


          #5
          It is likely that the device would deliver enough current to drive a larger relay, but I would not recommend it.

          Instead you should see if there are any other options. You mention in your first post that you purchased a temperature controller for the fan. This means that you very likely have installed at this point a low-voltage sensing system with a high-voltage high surge current switch.

          I don't know what it looks like but you might be able to introduce your X10 controller at the low-voltage side of the existing system.

          That way you use the swiching system that was designed for controlling the fan.

          If the system uses a simple resistive thermistor to measure temperature then you could use a relay module to short across the thermistor to fool it into thinking that it was very hot.

          If it uses a bi-metal spring to make contact when it it is hot (like a home thermostat) then it is even simpler - just make the same contact with the X10 relay module.

          If you do want to just wire in another module here is a unit designed for up to 1 H.P. motors with X10 2-way and last state restore on power fail.

          http://www.smarthome.com/2250aw.html



          Jon


          Originally posted by lpcalcaterra
          You got it!. Relay is fused.

          Before I fuse another fixture mod.... can I hack the module & install a "better" relay.

          What are my other options to control this attic fan?
          Jon Ort
          JonOrt@The--Orts.com
          (Remove the dashes in the address, spam is getting out of hand)

          Comment


            #6
            Thanks for the info Jon. I think I understand what you are saying.

            This is a line level stat. This is how it is currently wired.


            Option 3 - the new module may work with the same setup is above (?) Now that I look at it again, I way have caused the problem by leaving the Tstat in loop. If the module is off & the Tstat turns the fan on. Then I a got 120v feeding back through the blue load lead. Am I correct?


            Not sure how Option 2 with the relay could be setup?
            Larry

            Comment


              #7
              You have it wired just fine. Either the fixure module or the temp switch will turn the unit on. No shorts.

              Motors are a near short when they start. The only option you have with the switch you are using is to get the higher current switch I linked to. The motor itself should have the H.P. rating on it. You should be good to one H.P.

              Jon



              Originally posted by lpcalcaterra
              Thanks for the info Jon. I think I understand what you are saying.

              This is a line level stat. This is how it is currently wired.


              Option 3 - the new module may work with the same setup is above (?) Now that I look at it again, I way have caused the problem by leaving the Tstat in loop. If the module is off & the Tstat turns the fan on. Then I a got 120v feeding back through the blue load lead. Am I correct?


              Not sure how Option 2 with the relay could be setup?
              Jon Ort
              JonOrt@The--Orts.com
              (Remove the dashes in the address, spam is getting out of hand)

              Comment


                #8
                Originally posted by Oman
                The motor itself should have the H.P. rating on it.
                I gotta bring a brighter light up there to read the small print!

                Thanks for all of your asssitance.
                Larry

                Comment

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