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    qu145's Avatar
    qu145 Posts: 7, Reputation: 1
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    #1

    Jul 2, 2009, 03:41 PM
    Old Honeywell Miller Thermostat
    Hi. Let me first explain that I do not know very much about HVAC. I have an old honeywell thermostat that I could not find any info about. I've searched through posts and looked at diagrams, but can't seem to figure out how to hook this one up. I think I might have the wrong thermostat. I have a yellow and an orage, but on the new one. They are going to the same terminal. I don't know Im uploading pictures of old thermo, new one and the new one's connections.

    Here are links to the pictures. They're pretty hi res, so upload might be a little slow, sorry about that.

    Old thermo
    New Thermo
    New Thermo Connections

    Thanks in advance.
    qu145's Avatar
    qu145 Posts: 7, Reputation: 1
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    #2

    Jul 2, 2009, 03:46 PM

    BTW, the black wire was connected to the X terminal in the picture, sorry abou thtat I had it disconnected when I took the shot.
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    qu145 Posts: 7, Reputation: 1
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    #3

    Jul 2, 2009, 04:01 PM

    I'm assuming that
    Black wire = Common (Ground)
    Red wire = 24 volt
    Yellow and Orange = something to do with the A/C
    Green = Fan
    Blue and Brown = Heat

    I think I don't have the right thermostat and maybe I have a 2 stage heat pump.
    Thermostat says it's only for single stage with auxiliary heat.
    Any help would be appreciated
    siberianair's Avatar
    siberianair Posts: 360, Reputation: -4
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    #4

    Jul 2, 2009, 04:16 PM

    Yellow and orange should not be on same terminal... what kind of heatpump do you have? You would not have a two stage heatpump based on your old tstat. Lookes like y1 equals yellow. And the y/o is for orange. There should be a switch to be for one stage according to the tag inside new tstat.

    There is a chance your new tstat is wrong for your unit...
    qu145's Avatar
    qu145 Posts: 7, Reputation: 1
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    #5

    Jul 2, 2009, 04:28 PM

    It says Nordyne on it. Seems to be too many wires for the new thermostat. I'm thinking that it's not compatible.
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    qu145 Posts: 7, Reputation: 1
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    #6

    Jul 2, 2009, 04:59 PM

    Here is a pic of the connections at the heat pump. Hope this helps. I couldn't find any info or manual for it, so I'm hoping someone has some experience with this model.
    qu145's Avatar
    qu145 Posts: 7, Reputation: 1
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    #7

    Jul 2, 2009, 05:00 PM
    The top group of wires is coming from the old thermostat right now.
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
    Heating & Air Conditioning Expert
    		  
    #8

    Jul 2, 2009, 06:37 PM
    There is so much rust a corrosion on that last pic of the terminals I am surprised it works at all. A small wire brush and a pocket knife will do a world of wonders for those connections. It is only a 24 volt system so it is sensitive to bad connections.

    I might have a old change over wiring diagram for that thermostat or something close to it. It is on my other computer so I will try and post it later tonight.
    qu145's Avatar
    qu145 Posts: 7, Reputation: 1
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    #9

    Jul 2, 2009, 07:04 PM

    Thanks, I'll be sure to clean up those connections.
    hvac1000's Avatar
    hvac1000 Posts: 14,540, Reputation: 435
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    #10

    Jul 2, 2009, 08:50 PM
    This may help you. It tells what some different terminals do on older units.
    Attached Images
  1. File Type: pdf Older systems and base signals on newer ones.pdf (50.8 KB, 150 views)
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