(206) 949-5683, Top Rated Plumber, Seattle
Results 1 to 9 of 9

Thread: 120V Thermostat Change Out

Hybrid View

  1. #1

    Default 120V Thermostat Change Out

    Im in the process of installing a new thermostat in my home. When I pulled off the thermostat to see what voltage it was, the meter said it was 120V.

    So I went ahead and ordered a new 120V line voltage thermostat from Honeywell. Model # TL8230A. I wanted a programable thermostat that would function well and look nice on the wall.

    My question is the thermostat on the wall has 2 wires coming from the box. The new thermostat has 4 wires coming from it. Did I buy the wrong one or is there a way to wire this in correctly.

    BTW: This is for a 120V oil fired boiler baseboard heat system.

    Any help would be greatly appricated.

    Thank you
    Last edited by NY98M3; 11-21-2006 at 09:50 AM.

  2. #2
    Renovator Gencon's Avatar
    Join Date
    Nov 2006
    Location
    Etobicoke, Canada
    Posts
    50

    Default

    Nice stat. It has 4 wires because it is a double pole switch, which means it can control both legs of a 240volt heater.
    You need a 120 volt stat.

  3. #3
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
    Join Date
    Nov 2005
    Location
    Central Florida
    Posts
    2,685

    Default

    Or just use one of the switch legs.

  4. #4

    Default

    Quote Originally Posted by Mikey
    Or just use one of the switch legs.

    These are the instructions from Honeywell...Can you tell me which ones to hook up to my 2 wire system?

    http://www.thermostatshop.com/manual...n%20Manual.pdf

  5. #5
    Aspiring Old Fart, EE, computer & networking geek Mikey's Avatar
    Join Date
    Nov 2005
    Location
    Central Florida
    Posts
    2,685

    Default

    Looks like you could use either both black wires or both white wires; the thermostat apparently interrupts both pairs. Most electricians would choose to use the black pairs (since black normally is the "hot" wire), but it really doesn't matter if you're only switching one single-wire circuit. Use one color, and save the other for a spare in case the thermostat's contacts ever fail (not likely).

  6. #6
    In the Trades Bob NH's Avatar
    Join Date
    Oct 2005
    Location
    New Hampshire
    Posts
    3,307

    Default

    That thermostat seems to have some electronic functions, so it needs power to operate those functions. It appears to be more than just a switch.

    It appears to need power AND it needs to be able to switch.

    Also, original poster said he has a 115 Volt system, but has bought a 208/240 Volt thermostat.

    Something seems strange because I posted on this subject a few days ago but don't find it here. Is there another thread on this subject?

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •