Welcome, Guest. Please login or register.
Did you miss your activation email?

Username: Password:

Author Topic: Combining 2 thermostats  (Read 3519 times)

ralphxj

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 75
  • OWF Brand: Eco-Max
  • OWF Model: 125
    • View Profile
Combining 2 thermostats
« on: January 04, 2016, 11:17:43 AM »

My house is heated with baseboard hot water heat from an oil boiler (now wood burner) with 3 zones. I also have AC that was added in the attic recently (right before we bought the house). On the upper level of the house is where the bedrooms are, with the heat thermostat in the master bedroom. The AC thermostat for the entire house is in the hallway right outside the master. I would like to combine the 2 thermostats into one. Wiring isn't a problem, as I can run the heating wire start through the wall.

I understand the Rh and RC being the red from each source, however my confusion is what do I do with the white wires? Hook both into the thermostat, or just pick one and use that?

I don't have a need for the C wire yet, but I plan to go with a wifi thermostat in the future. Can I pull power from the  red wire from my boiler to power the C on the thermostat?
Logged

RSI

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3100
  • OWF Brand: HeatMaster
  • OWF Model: G200 and B250
    • View Profile
    • RSI
Re: Combining 2 thermostats
« Reply #1 on: January 04, 2016, 07:11:52 PM »

What are the connections currently on each thermostat?
Logged

ralphxj

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 75
  • OWF Brand: Eco-Max
  • OWF Model: 125
    • View Profile
Re: Combining 2 thermostats
« Reply #2 on: January 04, 2016, 07:15:25 PM »

I took photos, but the forum won't let me upload from my phone, guest they are too big.

The heat thermostat has a red and white from the zone valve and the AC has red, white, green and yellow.The AC line has a blue wire the is hidden behind the wall that I could use for C when I add a WiFi thermostat.
Logged

mlappin

  • Fabricator Extraordinaire
  • Global Moderator
  • Hero Member
  • *****
  • Offline Offline
  • Posts: 4140
  • OWF Brand: homebuilt, now HeatmasterSS
  • OWF Model: Martin Steel Works Gen 1 then, now a G200.
  • North Liberty, Indiana
    • View Profile
    • Altheatsolutions
Re: Combining 2 thermostats
« Reply #3 on: January 04, 2016, 07:46:12 PM »

C is actually for a common wire from the transformer or furnace, think of your neutral when doing 110v house wiring.

I have a Nest installed and in my case it worked fine with no C connection, depending on how everything is wired its possible the C connection can be backfed thru a relay to the thermostat, least this is what I gathered from my research. Your situation may be different.

I installed a new run of 7 wire thermostat wire and since i had it I went ahead and hooked the C up.
« Last Edit: January 04, 2016, 08:09:59 PM by mlappin »
Logged
Stihl 023
Stihl 362
Stihl 460
Sachs Dolmar 112 and 120
Homemade skid steer mounted splitter, 30" throat, 5" cylinder
Wood-Eze model 8100 firewood processor

HeatmasterSS dealer for Northern Indiana

RSI

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3100
  • OWF Brand: HeatMaster
  • OWF Model: G200 and B250
    • View Profile
    • RSI
Re: Combining 2 thermostats
« Reply #4 on: January 04, 2016, 09:55:01 PM »

I took photos, but the forum won't let me upload from my phone, guest they are too big.

The heat thermostat has a red and white from the zone valve and the AC has red, white, green and yellow.The AC line has a blue wire the is hidden behind the wall that I could use for C when I add a WiFi thermostat.

Is the white wire connected to the W? What is the other end of it connected to?
Logged

RSI

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3100
  • OWF Brand: HeatMaster
  • OWF Model: G200 and B250
    • View Profile
    • RSI
Re: Combining 2 thermostats
« Reply #5 on: January 04, 2016, 10:10:56 PM »

I took photos, but the forum won't let me upload from my phone, guest they are too big.

The heat thermostat has a red and white from the zone valve and the AC has red, white, green and yellow.The AC line has a blue wire the is hidden behind the wall that I could use for C when I add a WiFi thermostat.

Is the white wire connected to the W? What is the other end of it connected to?

To clarify, I meant the white wire on the AC thermostat.
Logged

ralphxj

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 75
  • OWF Brand: Eco-Max
  • OWF Model: 125
    • View Profile
Re: Combining 2 thermostats
« Reply #6 on: January 05, 2016, 05:22:14 AM »

I took photos, but the forum won't let me upload from my phone, guest they are too big.

The heat thermostat has a red and white from the zone valve and the AC has red, white, green and yellow.The AC line has a blue wire the is hidden behind the wall that I could use for C when I add a WiFi thermostat.

Is the white wire connected to the W? What is the other end of it connected to?

I would have to crawl into the attic and figure out where the wires connect. I haven't done anything with the AC, just the boiler end of things.
Logged

ralphxj

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 75
  • OWF Brand: Eco-Max
  • OWF Model: 125
    • View Profile
Re: Combining 2 thermostats
« Reply #7 on: January 05, 2016, 09:43:09 AM »

Ok doing more research, it looks like the white wire is used for heat only? Not sure why it's connected on my system. I will crawl up and figure out where it's connected, I'm guessing it's connected incase a heating element was added to the air handler in the attic and the installer just connected it our of habit.

I need to connect the Blue for a C wire anyone so I will check the W wire and connect the blue to C.
Logged

RSI

  • Hero Member
  • *****
  • Offline Offline
  • Posts: 3100
  • OWF Brand: HeatMaster
  • OWF Model: G200 and B250
    • View Profile
    • RSI
Re: Combining 2 thermostats
« Reply #8 on: January 05, 2016, 05:26:13 PM »

If it is not connected at the other end, you should be able to take the wires off the heater thermostat and connect the white the the W terminal and the red the RH. If there is a jumper between the RC and RH terminals, you will want to remove it.
Logged

ralphxj

  • Jr. Member
  • **
  • Offline Offline
  • Posts: 75
  • OWF Brand: Eco-Max
  • OWF Model: 125
    • View Profile
Re: Combining 2 thermostats
« Reply #9 on: June 09, 2016, 08:50:19 AM »

Ok, after a long delay wanting to wait until after I shut down the boiler and then finding out that the AC thermostat was acting odd (would switch the AC on and off rapidly for no reason) I finally finished this project.

Turned out to be VERY easy, just had to crawl into the attic and see that the white wire coming from the AC unit wasn't doing anything for the AC. So I removed it on the thermostat and hooked up the Red and White from the Boiler and the AC just like it was labeled and now have a WiFI thermostat controlling my AC and the heat on the upper level of the house!
Logged