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Nest power concetor


I'm trying to install a Nest thermostat and fund out tha I need a nest power adapter. I got it and now I'm trying to hook it to my heater controller board.

1- it's a heat only system (Thermolec on demand whater heating system)

2- My old thermostat had only two wires connected.

3- on the controller board there's different connectors from what is showing on the nest manual.( S,S2,W1,C,B,B,OT,OT)

4- Two wires connected ( W1,C) 

5- S1,S2 are with a jump 

 I would really appreciate if I could get some help with this since the letters for the connectors are different I'm not sure on how to do.

Comments

  • 109A_5
    109A_5 Member Posts: 1,343
    edited December 2023
    Hello @Pjandrada,
    Seems Thermolec likes things different and not real forthcoming with some common information.

    As far as I can tell;
    S1, S2 are for a Utility signal for Dual-Energy.
    B, B are for connection to an existing boiler.
    OT, OT Outdoor Sensor.
    W1, C Thermostat.

    It appears the Thermolec (TH-600) wants a contact closure between W1 and C for a call for heat. I believe the Nest Power Adapter provides such a contact closure (or suitable equivalent) between R and W wires in the group of three wires (C, R, W)
    Seems there is no easy source within the Thermolec unit for 24 VAC to power the Nest Power Adapter, so an additional 120 VAC to 24 VAC transformer may be needed.

    If you don't trust the Nest Power Adapter you can also add a relay so the Thermolec (TH-600) only sees the contacts of the relay, thus being an extra layer of isolation to protect your Thermolec (TH-600) equipment.



    With relay.




    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • Pjandrada
    Pjandrada Member Posts: 12
    Hello, thank you so much for answering my question.

    Do you think I could pull the 24v to power the nest connector directly from the thermolec of from the two other "Transformers" will send some pictures.


  • 109A_5
    109A_5 Member Posts: 1,343
    Hello @Pjandrada,
    So far the documentation I have found on www.thermolec.com seems exceptionally vague for this kind of system change / addition. They may not advise the use of thermostats like the NEST and others. You may want to contact Thermolec or a local service provider.

    I don't see any transformers in either of your pictures or a dedicated (un-switched) source of 24 VAC.
    First picture is zone valves.
    The second looks like a contractor or relay for the main power, or main power control to the heating elements.
    You may want to find someone that can do this kind of work. If you damage the Thermolec (TH-600) equipment it will get expensive to repair or replace.


    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • Pjandrada
    Pjandrada Member Posts: 12
    I took another look and found the transformer. As you can see in the picture. Again I really appreciate you taking the time to help me out 
  • Pjandrada
    Pjandrada Member Posts: 12

  • Pjandrada
    Pjandrada Member Posts: 12
    Diagram at the back of the boilers cober
  • Pjandrada
    Pjandrada Member Posts: 12

  • 109A_5
    109A_5 Member Posts: 1,343
    edited December 2023
    Hello @Pjandrada,
    Since you have zone valves is there a thermostat for each zone ?

    Connecting the NEST to the Thermolec (TH-600) equipment may be the wrong approach. Does your old thermostat go the zone valves or is there a separate zone valve controller there too ?

    There seems to be more to this story that your pictures are showing. Do you really want to risk damaging your Thermolec (TH-600) equipment to hook up a NEST ?

    Yes that is the transformer;
    Also the Yellow Arrow is pointing to a fuse, any connection should be after the fuse.
    There is probably 24 VAC between the Green and Blue arrows, but which is the R and which is the C terminals for the purpose of the NEST power ???

    You do realize there are lethal voltages inside that box with the power on !!!




    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • Jamie Hall
    Jamie Hall Member Posts: 22,924
    There are other ways to powering a Nest or other wi-fi thermostat than using the Nest power connector -- none of which run the risk of damaging your boiler's controller. May I ask if you have considered them, and if you have decided not to use them, why not?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Pjandrada
    Pjandrada Member Posts: 12
    @109A_5,

    You are wright, about the transformer. I don't know witch is C. 
  • Pjandrada
    Pjandrada Member Posts: 12
    @Br. Jamie, osb,

    I'm open to suggestions and recommendations on how to power the nest thermostat.
  • 109A_5
    109A_5 Member Posts: 1,343
    Hello @Pjandrada,

    Are you sure your old thermostat goes directly to the Thermolec (TH-600) equipment ? If so what controls or commands the zone valves to open ?

    One such NEST power alternative - put a dedicated 24 AC transformer at the NEST.

    Maybe more pictures from farther back and without the blue circle blocking the wire colors may help.

    Here is the wiring labeling translation for your original question.

    W1 = W
    C = RH




    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,570
    I'm going to take a wild guess here... the Zone valves are wired this way. You have 2 thermostats and two zone valves and the Red (End Switch) wires are connected to the Thermolec in this manner.



    If this can be verified by @Pjandrada /then the Nest wiring is very simple and you do not need the nest power adaptor. You need to install one wire as shown in blue






    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,570
    If the Zone valves are both using the transformer inside the Thermolec, then I would recommend another approach, as that transformer inside the Thermolec is already overused by the control system within the Thermolec plus the zone valves. I would seriously rethink the zone valve wiring to something more like the above diagram, with a dedicated transformer for the zone valves, independent of the Thermolec
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • 109A_5
    109A_5 Member Posts: 1,343
    Hello @Pjandrada,
    R and C connections ? Can't tell from the pictures and wire colors in the pictures don't seem to match the drawing.




    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • Pjandrada
    Pjandrada Member Posts: 12
    @109A_5,

    Yes you are right and after looking again I found out that the old thermostat does not connect directly to the circuit board. please see the picture,
  • Pjandrada
    Pjandrada Member Posts: 12

  • HVACNUT
    HVACNUT Member Posts: 5,750
    What's the black box to the right of the boiler? It looks like it's a transformer for the zone valves, but does it do anything else?
  • Pjandrada
    Pjandrada Member Posts: 12
    @HVACNUT,

    I also assume it's a transformer for the zone valves. It's not being used for anything else.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,570
    edited December 2023
    Can you show a close up of this part that we believe is the transformer for the zone valves?
    It is hard to read but I think is says Class 2 and it is a 24 volt and a 40 VA. but cant be sure.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • 109A_5
    109A_5 Member Posts: 1,343
    Hello @Pjandrada,
    Looking at the bigger picture it probably should be something like this below. It looks like the black cube to the very right is a transformer to power the zone valves.



    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,570
    edited December 2023
    I think if you look closely, you will find the yellow section looks like this
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,570
    edited December 2023
    If it looks like my previous post then you need only add one wire (the lighter blue wire) and make sure that the wire you choose top be R from the transformer goes to R on the NEST thermostat, and the W from the NEST thermostat connects to one of the black wires on the zone valve motor..... Finally the C from the transformer gets connected to the other motor on the zone valve motor and the C from the NEST



    It is important to connect R transformer to R thermostat and W thermostat to the zone valve motor. Otherwise the C transformer to C thermostat will not work.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • 109A_5
    109A_5 Member Posts: 1,343
    Hello @Pjandrada,
    Just for clarity, the 4 wires of the zone valve unit, Red wires are the zone valve end switches, the Black wires are the zone valve motors, see label on the zone valve cover. I think you crossed your Black and White wire pairs you added to your picture of the whole system.

    The zone valve end switches are what directly activates the Thermolec (TH-600) equipment. This verifies the valve is open for the water to flow.


    National - U.S. Gas Boiler 45+ Years Old
    Steam 300 SQ. FT. - EDR 347
    One Pipe System
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,570
    edited December 2023
    I'm guessing by your comment
    2- My old thermostat had only two wires connected.
    you mean to say that there are only 2 conductors in the wire that goes to the thermostat. In that case the Power Adaptor from NEST will be a necessary add on. The diagram provided by @109A_5 is the best advice.

    However it you have an extra conductor in that thermostat wire, the Adaptor is not necessary.
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
  • Pjandrada
    Pjandrada Member Posts: 12
    @109A_5 and @EdTheHeaterMan,

    Thank you so much for your help with this, I really appreciate it. I will try the installation and let you guys know how it went.