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Thermostat question

cuttercutter Posts: 235Member
I am currently using Honeywell thermostats that are 35 years old. The round ones with the mercury bulb in them. they have three terminals R W Y. The R and W go to the R and W on the Caleffi ZVR 104 Relay zone valve control. The W was never used.
I am wanting or thinking about going to the Honeywell RTH111 Series non-Programmable thermostat. That thermostat takes two AAA batteries. Or it can be wired for 24 Volts. I would like to wire it for 24 volts, but no where in the directions that came with a RTH111 thermostat that I bought 3 years for my air conditioner says how to wire in 24 volts.

I am guessing that if I connect my R and W to the R and W in the RTH111 and put batteries in the thermostat everything would be operational.

I have wired in a separate 24 volt transformer for another use. I am wondering if I can take the 24 volts from that transformer and power up the RTH111 thermostats, if so, how do I do that? If I can do that would the 24 volts damage the Caleffi ZVR104 Relay?

Comments

  • Jamie HallJamie Hall Posts: 8,749Member
    Why do you want to replace the old Honeywells? Those things are bulletproof and do at least as good a job of holding temperature steady as any of the new ones do.

    But if you do want to use the new-fangled ones, I'd use the batteries and not worry about the 24 volt power. The batteries will last for a year or so...

    And then you could PM me and we could see if you could package up the old Honeywells and send them to me. I wouldn't mind having them at all!
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • ZmanZman Posts: 4,363Member
    I don't see a common on the t-stat. https://customer.honeywell.com/resources/techlit/TechLitDocuments/69-0000s/69-2060EFS.pdf
    I think you are stuck with the batteries.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • EBEBRATT-EdEBEBRATT-Ed Posts: 4,381Member
    edited November 5
    Agree with @Zman. Don't see a common for the 24v. Use the batteries and connect the stat to R & W
  • cuttercutter Posts: 235Member

    Why do you want to replace the old Honeywells? Those things are bulletproof and do at least as good a job of holding temperature steady as any of the new ones do.

    But if you do want to use the new-fangled ones, I'd use the batteries and not worry about the 24 volt power. The batteries will last for a year or so...

    And then you could PM me and we could see if you could package up the old Honeywells and send them to me. I wouldn't mind having them at all!

    Jamie, I had a round Honeywell on my air conditioner just like the ones for the boiler. The air conditioner was not working properly so I changed to the RTH111 Honeywell and fixed the problem.

    Right now on my largest zone the thermostat is set to 70 degrees , the panel is still sending heat to the zone when the thermostat is reading 72* and the boiler water temperature is reading 160* or so. I was thinking it was a thermostat problem. That panel switches one of the zone valves open and close before that room reaches the set point. I was thinking that was a thermostat problem also. Maybe Not.

    The neighbor had a problem with the same thermostat where the thermostat would not stop the heat when it reached the set point. I took off his thermostat and blew out 40 years of dust and reinstalled it and the problem was fixed. I tried that to this one and the zone still overheats. I am burning wood now so I can just stop feeding the boiler to stop the heat. But when I can get a burner guy out and get the oil boiler fired I won't have that same option.

    I have a couple of extra Thermostats, I think I will swap the part that does the switching on and off, and see if the problem goes away. I just thought in time these thermostats just died. On the forum here one of the guys said he had got a no heat call and the problem was a mechanical thermostat, I assumed it was one of these.
  • cuttercutter Posts: 235Member
    Zman said:

    I don't see a common on the t-stat. https://customer.honeywell.com/resources/techlit/TechLitDocuments/69-0000s/69-2060EFS.pdf
    I think you are stuck with the batteries.

    Zman, the link you gave is not the exact same instructions that came with the thermostat, but the one I bought for the air conditioner is maybe 3 or 4 years old and things change. I have not looked, but maybe the exact one I bought for the air conditioner is no longer available.
  • HVACNUTHVACNUT Posts: 1,524Member
    > @cutter said:
    > Why do you want to replace the old Honeywells? Those things are bulletproof and do at least as good a job of holding temperature steady as any of the new ones do.
    >
    > But if you do want to use the new-fangled ones, I'd use the batteries and not worry about the 24 volt power. The batteries will last for a year or so...
    >
    > And then you could PM me and we could see if you could package up the old Honeywells and send them to me. I wouldn't mind having them at all!
    >
    > Jamie, I had a round Honeywell on my air conditioner just like the ones for the boiler. The air conditioner was not working properly so I changed to the RTH111 Honeywell and fixed the problem.
    >
    > Right now on my largest zone the thermostat is set to 70 degrees , the panel is still sending heat to the zone when the thermostat is reading 72* and the boiler water temperature is reading 160* or so. I was thinking it was a thermostat problem. That panel switches one of the zone valves open and close before that room reaches the set point. I was thinking that was a thermostat problem also. Maybe Not.
    >
    > The neighbor had a problem with the same thermostat where the thermostat would not stop the heat when it reached the set point. I took off his thermostat and blew out 40 years of dust and reinstalled it and the problem was fixed. I tried that to this one and the zone still overheats. I am burning wood now so I can just stop feeding the boiler to stop the heat. But when I can get a burner guy out and get the oil boiler fired I won't have that same option.
    >
    > I have a couple of extra Thermostats, I think I will swap the part that does the switching on and off, and see if the problem goes away. I just thought in time these thermostats just died. On the forum here one of the guys said he had got a no heat call and the problem was a mechanical thermostat, I assumed it was one of these.

    Dust is about the only natural predator to the T87F.
    Is the panel actually powering the zone valve open?
    Have you checked the zone valve itself?
    What brand and model zone valve?
    Its possible the valve is stuck open so the large zone still heats when another zone comes on.
  • cuttercutter Posts: 235Member
    HVACNUT, Today I took apart the two thermostats that the panel light say are still calling for heat and cleaned out all the dust I possibly could. I will see if that helps.

    The lights on the panel say they are wanting heat. Or I think that is what the lights mean.

    I am not sure what you mean have iI checked the zone valve itself.

    The zone valves are new Honeywell V8043 E 1012, three of those and one V8043 E 1020. The 1020 is the large zone and is zone one.

    If the large zone is stuck open the lights on the panel are still on also.


  • Jamie HallJamie Hall Posts: 8,749Member
    I know it seems obvious, and therefore you have probably already checked, but...

    a: have you turned the thermostats down -- well below the room temperature -- to see if they actually turn off? If these are the mercury type, there are no contacts to weld, but it is possible that something in the mechanism might have gotten damaged (not that there is much to damage -- a bimetal coil with a mercury bulb attached is about as simple as it gets).

    b: have you checked that the thermostats are actually level? One of the few weaknesses of the mercury type is that they are very sensitive to being off level.

    c: if you disconnect the two wires to the thermostat, does the call for heat stop? It wouldn't be the first time that the wires got shorted...
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • cuttercutter Posts: 235Member
    Jamie, I have turned the thermostat way down and the call for heat stopped.

    They are level

    I have not tried C, but don't think that would be the problem. I can try that tomorrow.
  • Jamie HallJamie Hall Posts: 8,749Member
    It is possible that the calibration has slipped. Rare, but happens. Take the outer cover right off (leave the 'stat on the wall) and watch the mercury bulb as you turn the temperature dial. It should be flipped to open at high temperature, and then flip over to heat at the room temperature, or near it.
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • cuttercutter Posts: 235Member
    edited November 7
    Jamie, I appears the culprit was Mr. dust. After I went in and blew out dust, I went back in and took a tooth brush and cleaned off the wires that are at the end of the mercury bulb gently. All thermostats seem to work fine now. The zone that would open and close several times before reaching set point did not have a lot of dust. But by cleaning off the wires at the end of the mercury bulb the zone would come on line and stay until the set point was reached. On the bottom right of the thermostat there is a copper arrow with a triangle in it. that arrow was moved way to the right. I moved it back so the number 4 was in the triangle like the other thermostats. That may have been part of the problem, don't know. Everything seems to work fine now.
    For about the last ten years now I have ran this heating system manually. built a fire when the house was cold and stopped feeding the boiler when a thermometer said the house was 70* or so. It sure is nice having controls that work now. I have two things left to add on One is a high temperature alarm the other is sensors to read boiler supply and return temperature from the upstairs. Thanks for your suggestions and help.

    @HVACNUT if you are still clicking on this you convinced me to keep using the old Honeywells, thanks.
  • GBartGBart Posts: 591Member

    Why do you want to replace the old Honeywells? Those things are bulletproof and do at least as good a job of holding temperature steady as any of the new ones do.

    But if you do want to use the new-fangled ones, I'd use the batteries and not worry about the 24 volt power. The batteries will last for a year or so...

    And then you could PM me and we could see if you could package up the old Honeywells and send them to me. I wouldn't mind having them at all!

    Mechanical thermostats are junk, the best a bimetal can do is maybe a 2 degree separation, maybe usually they wander 3-5 degrees, digital thermostats see temperature in 10ths of a degree, 70.0, 70.1, 70.2, etc, they are also learning and work to keep the set point perfect by adjusting the on and off of every cycle, you set a good digital for 70 and it will be and remain 70 and it's more efficient.
  • Jamie HallJamie Hall Posts: 8,749Member
    They may be junk. So's my 48 year old truck. Oddly, the thermostats are older than the truck and they are still running flawlessly...

    I'd rather have something that will run and keep on running and is easy to work on than something which is the latest and greatest -- for a week, until it breaks and something newer and more expensive comes out.

    But that's just me...

    Oh -- and the "swing" using my T87 for control but reading an accurate separate thermometer is around half a degree. Which I can't feel...
    Jamie



    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.



    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
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