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    New Thermostat 3 Wire Hot Water Boiler System (12 Posts)

  • Michaelwhit83 Michaelwhit83 @ 12:59 PM
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    New Thermostat 3 Wire Hot Water Boiler System

    I have a 3 stage hot water boiler system with three different thermostats in my house. I went to change out the first thermostat downstairs with a new digital that said it was compatible with a hot water system. The only thing is the wiring diagrams are different, the three wires I have on my old edwards engineering thermostat are W6 , R5 , and 4B .. Could anyone shed some light on which socket these wires go in on a new digital, or if this will even work at all. I really need to change it out because its hard to set accurately because the old lens is faded pretty bad.

    Thank you for your time,
  • Zman Zman @ 8:25 AM
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    The other end?

    Where do the wires go on the other end? It sounds like you have a 2 stage t-stat but it could be something else.
  • Plumdog Plumdog @ 7:20 AM
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    What type zone valves do you have?

    Are they White-Rogers 1311 style perhaps? If so, 4 is power open, 6 is power closed, and 5 is common. But not all digital stats will work with these. You can call the tech support number on the literature and find out. Some stats will work after changing one of the settings in the setup program. White-Rogers has a digital that is compatible.
  • Michaelwhit83 Michaelwhit83 @ 9:03 PM
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    Thanks for the help. The wires are not colored and I are all grey.. I have included a picture if that helps..
  • Plumdog Plumdog @ 6:58 AM
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    Looks like three-wire snap contact type thermostat

    but down by the boiler there should be Zone Valves (look like grey boxes with wires going to them). 
  • Michaelwhit83 Michaelwhit83 @ 9:13 PM
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    Ok it's been a while..

    Well I gave up on this but now I'm back again.. I have taken some more pics and I am hoping someone can guide me through this as I don't want to screw this up. I am changing my upstairs bedroom thermostat.. All the wires on all three of the thermostats are all the same color so I can't differentiate them from one another other than where they are already hooked up on the white rodgers.. can anyone help me out.. I am posting a pic of the new thermostat and the old one that I want to change out.
  • Zman Zman @ 12:07 AM
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    3 wires

    That is kind of an odd t-stat paired with those zone valves.
    In the mechanical room, where do the 3 wires go? Normally one would go to a transformer and another to one of the yellow wires on the zone valve. Where does the third wire go?
    What model is the new t-stat?
  • Pughie Pughie @ 9:18 AM
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    Wow, Edwards - they were something!
    As Plumdog said - 5 is common/4 opens  my guess is that the wire on terminal 6 is not being used unless you have something exotic.Those look like Hwell 2 wire zone valves. If it works with your existing W/R stat just use the wires that are going to terminals 4 & 5. I'd put the wire thats on terminal 5 on Rh on your new stat & the wire thats on terminal 4 on W. You should be good to go. I don't see a "C" terminal on your new stat.
                                                John Pughe
  • Michaelwhit83 Michaelwhit83 @ 6:00 PM
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    nailed it..

    You hit it right on the head.. I went and looked through the tangles of wire that ran to the valves and one wire is not being used. It is just taped off and the other two go to the red and yellow wires coming out of the bottom. Whoever wired this thing could have at least used some zip ties or something.. I will try to hook up the thermostat right now and see how it goes. Thanks.
  • Michaelwhit83 Michaelwhit83 @ 9:05 PM
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    Another quick question

    On a boiler system since I have three thermostats and it opens at random to send heat where needed... what is the best way to tell if the new thermostat is working as it should right now? If I shut the others off shouldn't it just go to the section of the house where the only thermostat is on??
  • Zman Zman @ 11:07 PM
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    Zone valve

    If you slide the lever on the zone valve, you can tell if it is in the open or closed position. If it slides freely with no resistance the valve is open. If you can move it but with significant effort it is closed. You should be able to turn up the t-stat, then check if the valve is opening.
  • Michaelwhit83 Michaelwhit83 @ 6:04 PM
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    seems to be working

    Thank you all for the help.. it seems to be working now.. it will be nice to have digital thermostats that I can actually read now. Talking to a local company about getting a new boiler system all together with my tax check here pretty soon. It works alright but it's definitely got some age to it, probably was put in somewhere around 1960. Lol.. and its more than likely not the most efficient.. it's a beast though, probably gonna take 4 guys to get it out of there if I change it out.. any recommendations on quality boiler brands to look into.
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