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  • Installing digital programmable thermostats

    Hi,

    This is my first post. I recently bought a new home, the builder "cheaped out" and installed non-programmable thermostats in each of the 2 zones - I want to upgrade to programmable units.

    I am replacing Robert Shaw (Invensys) non-programmable thermostats with LUX model WX-500 programmable units. My problem is in the wiring - the 2 current (pardon the pun) units are wired differently, and cannot be configured the same as the replacements, as follows:

    Unit 1 (first floor zone) 3 wire configuration (RC & RH jumped together, w, and Y)

    Unit 2 (second floor zone) 6 wire configuration (RC & RH jumped together, W, Y, B, O, G)

    Both units are the same model Robert Shaw thermostat.

    As I look at the replacement thermostat, I see that this unit does not offer connections for the existing "B" or "O" marked wires in the original config - anyone know what these are for and what to do about them?

    The house will eventually have central air conditioning (coil is installed in system), but I have not purchased/installed the compressors yet - probably next year sometime.

    I appreciate any/all comments or suggestions

    Thanks,

    Kevin O
    (BostonKevinO)

  • #2
    Double check and make sure the thermostat is compatible with your system. For instance, a multi stage heat pump with auxiliary heat requires a thermostat designed for that type of system and is not compatible with some of the less expensive thermostats commonly found at lowes or home depot. The back of the thermostat packaging should tell what type of system it works with.

    Hope this helps... good luck.

    Comment


    • #3
      Hi Chickenwing,

      Thanks for the feedback - regarding your suggestion I belive that the replacement thermostat is correct for the system (I'll check again). This is not a heat pump, and it has nothing exotic or advanced wired into it - so seems to be right.

      There was a diagram that came w/ the replacements install directions that referenced wiring when other connections besides rh, rc, w, y & g were present - it just didn't happen to include wires (actually connection posts) marked "b" and "o"...

      I'll keep on researching, when I get an answer I'll post it here in case anyone needs it in the future...

      Thanks again,

      Kevin O'


      quote:Originally posted by chickenwing

      Double check and make sure the thermostat is compatible with your system. For instance, a multi stage heat pump with auxiliary heat requires a thermostat designed for that type of system and is not compatible with some of the less expensive thermostats commonly found at lowes or home depot. The back of the thermostat packaging should tell what type of system it works with.

      Hope this helps... good luck.

      Comment


      • #4
        Hi,

        Here's the scoop - turns out the config I described (see above posts) represents a master/slave relationship between the 2 thermostats (upstairs in zone number 2 the 6 wire config is the master - downstairs in zone number 1 the 3 wire config is the slave).

        SOooooooooo The company (LUX) responded to my inquiry (by phone) and told me that their model # TX1500 (about $20.00 more) is capable of the master config, but that the downstairs will remain non-programmable (a slave to upstairs zone).

        I guess I can live w/ that for now, should still save on fuel costs overall (especially cooling in summer) - and I'll manually adjust zone 1 as necessary when needed...

        Not a perfect solution - but a solution.

        Kevin O'

        Comment


        • #5
          Hi All,

          Well, I installed the new thermostat (LUX model TX1500) today. It was a snap, I marked the wires as I disconnected them from the old unit, reversed the process to connect the new unit, slapped in 2 AA batterys, turned the power back on at the breaker, and ta-daa! it works perfectly...

          Programmed the unit to correspond to our schedules (including seperate heating schedules for SAT & SUN

          This thing is really cool - it even tracks the hours on my filter and reminds me when to change it! Also, The people at LUX are to be commended for excellent customer service - I'd buy their stuff again.

          Coincidentally, unit just kicked in to begin heating up zone 2 (right on time!). It will be great to step into a nice pre-warmed bathroom tomorrow a.m.

          Cheers!

          Kevin O'

          Comment


          • #6
            Congratulations! [^]
            Try

            Comment


            • #7
              I just purchased a new digital thermostat. When I went to remove the old one and install this new one I noticed that on the old thermostat the red and white wires were used but there was a blue and black one the was unhooked. So I went ahead and setup the new thermostat for a two wire configuration, but does anyone know what these two wires are? Perhaps one is able to supply power so I don't have to use batteries? I mean the original thermostat did function without these two wires installed.

              Any insight and help would be great,
              Thanks!

              Comment


              • #8
                pof5

                Welcome to the Home Repair Forum

                Your two wire system is only heating or cooling, The four wires would be for both. As long as you have it wired for two wire config you should do just fine.

                16x80

                Comment


                • #9
                  I'm confused?
                  Right now my system is wired for only heating or only cooling?

                  And those other two wires are for the other, and by not being hooked up, then half my system wasn't hooked up?

                  Thanks

                  Comment


                  • #10
                    Ok. So your saying you have both heating and cooling in your home. Did they both work before? and do they both work now? The only systems I know of that run both heating and cooling on two wires are in a manufactured home, This would be where the furnace changed the polarity on the wires and makes the thermostat work backwards to allow for cooling.

                    Throw me a bone here. 16x80

                    Comment


                    • #11
                      16x80
                      sorry about that confusion. Ok, apparently the home only has heating. So now I'm wondering are those two other wires dummy wires? Or possibly can one of those power the actual thermostat.

                      Lastly I read somewhere that with a two wire configuration, you really can't put a wire in the wrong place, ie mix it up. Is this correct?
                      thanks

                      Comment


                      • #12
                        pof5

                        The red wire is power to the thermostat, the white wire is for the blower. The red wire carries the 24 volts to the thermostat, If your particular thermostat runs off of batteries your pretty much stuck using the battery power. You could exchange it for a more advanced thermostat that runs off of 24vac and uses a battery back up to hold memory. Other than that the other two wires would be inplace for when you decided to upgrade and install AC.

                        Hope this helps...

                        16x80

                        I dont see how anyone could possibly live without AC!

                        Comment


                        • #13
                          Hi,

                          Probably a stupid question !! I'm replacing an old Honeywell thermostat, there are no W,Y,G etc. markings.There is a white wire and a blue/grey one. I ony have a gas furnace(i.e. no AC). Does W stand for white, what is the other wire for ??

                          Thanks

                          Jay

                          Comment


                          • #14
                            Not a stupid question at all.

                            W stands for white which means heat which means gas valve.
                            R stands for red which means the hot leg of the 24 volt circuit. (where the power comes from)
                            G stands for green which would power the indoor blower if you had A/C and a blower relay.
                            Y stands for yellow which is to send power to the outdoor condensing unit for A/C
                            Some have R/C which means you need a jumper from red if you have A/C.

                            Naturally the equipment can't tell what color is connected to what part, its just for us dumb humans to keep track.

                            In the case of using a set back t-stat for heat only, just connect one wire to W and the other to R. It doesn't really matter which to which.

                            However, you do need to follow the directions for setting the cycle control on the t-stat.

                            Comment


                            • #15
                              I just bought a LUX TX1500 and i'd like to install it. I have 3 electric heaters (with fans) in the house and no cooling). 2 heaters are controlled by the thermostat downstairs. 1 heater is controlled by the thermostat upstairs. Both existing thermostats are made by King. I'd like to install the TX1500 downstairs.

                              I unscrewed the cover plate for my downstairs thermostat and was a little puzzled. Instead of the expected white, yellow, green wires, i see four thick wires (probably around 10 AWG). 2 wires (one red, one black) are hooked into one relay (not sure if that's the right word for it), and 2 wires (one red, one black) are hooked into the other relay.

                              Is my new thermostat compatible with the existing heating system?

                              Comment

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