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    hmerazo's Avatar
    hmerazo Posts: 7, Reputation: 1
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    #1

    Sep 26, 2007, 05:42 PM
    what is the common wire?
    I'm changing my old thermostat by one programmable; the new thermostat don't use batteriesand the wires that I have available are Y, G, R, W, what wire can I use in the x or common wire?
    esquire1's Avatar
    esquire1 Posts: 2,483, Reputation: 209
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    #2

    Sep 26, 2007, 05:50 PM
    You will need to pull another wire through the wall. Or you can return the stat and purchase one with batteries
    hmerazo's Avatar
    hmerazo Posts: 7, Reputation: 1
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    #3

    Sep 26, 2007, 06:51 PM
    And this cable that I need from where may I pull it? Idont have another easy way?
    wheatnbarley24's Avatar
    wheatnbarley24 Posts: 63, Reputation: 3
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    #4

    Sep 26, 2007, 06:57 PM
    Like esquire said, returning it for one with batteries is the easiest way for an inexpierienced person to do
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #5

    Sep 26, 2007, 11:06 PM
    Contrary to beliefs, this product will allow him to use a 5 wire stat with only 4 wires:

    Venstar Inc. - Add-A-Wire ACC0410
    hmerazo's Avatar
    hmerazo Posts: 7, Reputation: 1
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    #6

    Oct 16, 2007, 06:16 PM
    I have an add a wire device. I need an common wire, because I only have 4 wires, what ports I need to jump, thanks
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #7

    Oct 16, 2007, 06:44 PM
    Page 2 of the instructions. Should be pretty straighforward. G and Y will share a wire. I can't really help you because you didn't tell us:

    1) What wire colors you have
    2) What terminals are they currently connected too.
    3) What add a wire device you bought.

    One part essentially gets tucked in the wall behind the stat. The other gets installed in the furnace.
    labman's Avatar
    labman Posts: 10,580, Reputation: 551
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    #8

    Oct 16, 2007, 07:41 PM
    You will need to read and follow the directions for the device you have. Chances are, you connect the red wire to RH & RC, the white to W. Then the device allows you to make either the yellow or green do the work of both. The other, connects to com at both the furnace and thermostat.
    hmerazo's Avatar
    hmerazo Posts: 7, Reputation: 1
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    #9

    Oct 16, 2007, 08:07 PM
    Quote Originally Posted by KeepItSimpleStupid
    Page 2 of the instructions. Should be pretty straighforward. G and Y will share a wire. I can't really help you because you didn't tell us:

    1) What wire colors you have
    2) What terminals are they currently connected too.
    3) What add a wire device you bought.

    One part essentially gets tucked in the wall behind the stat. The other gets installed in the furnace.

    I have 4 wires (green, yellow, red and white) my new thermostat need a common wire and I don't have one, my device is a robertshaw int-43
    The four wires are connected the red is jumpered with rh and rc
    hmerazo's Avatar
    hmerazo Posts: 7, Reputation: 1
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    #10

    Oct 17, 2007, 04:33 PM
    Quote Originally Posted by labman
    You will need to read and follow the directions for the device you have. Chances are, you connect the red wire to RH & RC, the white to W. Then the device allows you to make either the yellow or green do the work of both. The other, connects to com at both the furnace and thermostat.

    Excuse me but I don't have instructions for this device, and I want to know what wire may I use like common wire or what wire can I jump with what to put it on my new thermo?
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #11

    Oct 17, 2007, 04:46 PM
    What about the other colors as connected to the OLD stat.
    I know Red is connected to Rc and Rh; that's not going to change
    It was probably connected to R on the old stat (T or F)
    White is connected to terminal _W__ (cooling call)
    Green is connected to terminal _G____(fan)
    Yellow is connected to terminal _Y____. (heating call)

    True or False?

    This is just to make sure we are on the same page.

    What will happen is that the W and Y terminals from the stat will to the 3-terminal device and the other end is then connected to white. This small device will be tucked in the wall.

    Yellow will then become common. If you have some black tape, put it on the wire at both ends.

    The other part will go in the furnace and connected appropriately.


    Open mouth, I'm spoon feeding now:

    In post #2, the blue text is a link.
    Click on it.
    At the bottom of the page, you'll have to put your glasses on for this, there is a small PDF Icon with the words "Owner's manual".
    Click on that.

    The instructions are very straightforward.

    Yell, if you need help.
    hmerazo's Avatar
    hmerazo Posts: 7, Reputation: 1
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    #12

    Oct 19, 2007, 03:22 PM
    Quote Originally Posted by KeepItSimpleStupid
    What about the other colors as connected to the OLD stat.
    I know Red is connected to Rc and Rh; that's not going to change
    It was probably connected to R on the old stat (T or F)
    White is connected to terminal _W__ (cooling call)
    Green is connected to terminal _G____(fan)
    Yellow is connected to terminal _Y____. (heating call)

    True or False?

    This is just to make sure we are on the same page.

    What will happen is that the W and Y terminals from the stat will to the 3-terminal device and the other end is then connected to white. This small device will be tucked in the wall.

    Yellow will then become common. If you have some black tape, put it on the wire at both ends.

    The other part will go in the furnace and connected appropriately.


    Open mouth, I'm spoon feeding now:

    In post #2, the blue text is a link.
    Click on it.
    At the bottom of the page, you'll have to put your glasses on for this, there is a small PDF Icon with the words "Owner's manual".
    Click on that.

    The instructions are very straightforward.

    Yell, if you need help.



    OK my wires are connected in this way red to rh and rc, white to w, yellow to y and green to g, the instructions for the venstar add a wire are very clear but the problem is that I don't have a brown wire, my device is a robertshaw int-43 it have a y-diode with terminals Y and W in one side and the instructions said that this need to be connectedin w and y (jumper)but the instructions show that I have an x wire. My new thermostat is a honeywell t7350d 1008, thaks for your help
    T-Top's Avatar
    T-Top Posts: 1,871, Reputation: 100
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    #13

    Oct 19, 2007, 04:52 PM
    You can add a resistor and jump from W to C and it will do fine Carrier did it for years. (270 ohm 10 watt resistor)
    J Costa's Avatar
    J Costa Posts: 88, Reputation: 9
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    #14

    Oct 19, 2007, 05:08 PM
    You should have a common wire inside the air handler find what color they are using in there and if you don't have any extra wires behind the thermastat then you will have to run one from the air handler to the therm it should be a rather short run. Othher than that I think you are looking at rewiring from the therm all the way to the condenser.
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #15

    Oct 19, 2007, 05:41 PM
    X on the honeywell is common. I can't find a manual for the int-43 add a wire device.

    You were missing a common all along. This is the other side (Where Red is not connected to) of the transformer in the furnace. This is the wire you need for the new stat.
    KISS's Avatar
    KISS Posts: 12,510, Reputation: 839
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    #16

    Oct 19, 2007, 06:17 PM
    When you hook up the add-a-wire device at both ends, you should have a wire left over.

    It should be Y or W.

    One of these (Yel or White) (the cable running to the furnace) will have to be disconnected and moved to the Furnace common terminal. This then goes to X on the thermostat. I suggested yellow to become X or Common.

    Are you having trouble locating common at the furnace?
    hmerazo's Avatar
    hmerazo Posts: 7, Reputation: 1
    New Member
     
    #17

    Oct 19, 2007, 06:30 PM
    Quote Originally Posted by KeepItSimpleStupid
    When you hook up the add-a-wire device at both ends, you should have a wire left over.

    It should be Y or W.

    One of these (Yel or White) (the cable running to the furnace) will have to be disconnected and moved to the Furnace common terminal. This then goes to X on the thermostat. I suggested yellow to become X or Common.

    Are you having trouble locating common at the furnace?
    Thanks for all, but I don't know nothing about AC and my furnace is on the roof and because that is not easy to me reach it, I think that ill stay with my old thermo, thanks for your help and your time. Thanks a lot really
    T-Top's Avatar
    T-Top Posts: 1,871, Reputation: 100
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    #18

    Oct 19, 2007, 07:19 PM
    They do make a cheaper thermostat that works just as good and uses batteries so you don't have to have a common wire to make it work. Take the one back you bought and exchange it for a thermostat that will work for your system with out the retrofit involved. Good luck.
    labman's Avatar
    labman Posts: 10,580, Reputation: 551
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    #19

    Oct 19, 2007, 07:38 PM
    I can't rate T-top again, but his last post may be the best one yet.
    rockythermostat's Avatar
    rockythermostat Posts: 1, Reputation: 1
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    #20

    Jul 1, 2010, 07:02 AM
    U should have blue wire... if not then change Ur thermostat... go for RTH7600D..!

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