New Thermostat Wiring


  #1  
Old 12-26-05, 09:48 AM
airahcaz
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New Thermostat Wiring

I have a Honeywell Gas furnace that fills hot water baseboards on 2 floors. From the Furnace are 2 Taco Zone Valves. There are 2 wires from the furnace, but then 3 from each of the 1, 2, and 3 labels on each Taco Valve. Green ends up not being used and is cut off at transformer. Ultimately, there are red and white, spliced several ways, which then these 2 wires (ech red and white) run up from the transformer into the apartments. I have removed my old mercury heat only thermostat to replace it, and alas, there are 4 wires, green and red spliced together, and black and yellow spliced together, each then connected to opposite screws (no labels whatsoever) on this older thermostat!

I bought a new digital thermostat and attempted to simply match the colors, this obviously didn't work.

So what do I do with the R, G, Y, and Black wires to the new?

I think R is for Rh, that much should be fine. Black to C or Common? G and Y go where?
 
  #2  
Old 12-26-05, 10:19 AM
H
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two wire heat

if your old control had two wires twisted together under one terminal it was likely that the wire run was a bit long and the installer ran a wire that was too thin in diameter... to make up for this, he twisted the two wires together to make up for the insufficient gauge(diameter)...think of the twisted wires as one, and this will eliminate some confusion. For the heat only thermostat you have two connections, Rh on one side and W on the other, done. Just make sure you have the same twisted pairs as originally done or the unit will run non-stop. Terminal 1 on the zone valve goes to the thermostat W connection, terminal 2 goes to T2 on the aquastat, and terminal 3 goes to T1 of the aquastat. When the stat closes it will drive the zone valve and close the end switch within a minute and this will start the circulator (and fire the boiler if the water isn't hot enough).
Good luck
 
  #3  
Old 12-26-05, 10:32 AM
airahcaz
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Originally Posted by hvac01453
if your old control had two wires twisted together under one terminal it was likely that the wire run was a bit long and the installer ran a wire that was too thin in diameter... to make up for this, he twisted the two wires together to make up for the insufficient gauge(diameter)...think of the twisted wires as one, and this will eliminate some confusion. For the heat only thermostat you have two connections, Rh on one side and W on the other, done. Just make sure you have the same twisted pairs as originally done or the unit will run non-stop. Terminal 1 on the zone valve goes to the thermostat W connection, terminal 2 goes to T2 on the aquastat, and terminal 3 goes to T1 of the aquastat. When the stat closes it will drive the zone valve and close the end switch within a minute and this will start the circulator (and fire the boiler if the water isn't hot enough).
Good luck
I was just thinking that as well, so I will splice (or just twist them together) Black and Yellow as original, and connect to W? then splice Red and Green and Connect to Rh (it has a jumper to Rc, so I guess I can leave that)

So he ran thermostat gauge wire, connected to the bigger gauge white and red, instead of just running up the red and white all the way? I guess in case I change my furnace or add another component, the wires are there for use already? Although, to be honest, I have no idea where in the wall the red and white are connected to the thermostat wire.

awesome quick response, you guys are amazing
 
  #4  
Old 12-26-05, 04:52 PM
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airahcaz

The red & white are most likely real thermostat wire. If I were a betting man, I would say the smaller R, G, Y, & Bk are telephone wire (std colors for phone wire). Doubling up on the phone wire amounts to a single thermostat wire, more or less.
 
  #5  
Old 12-26-05, 05:55 PM
airahcaz
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Originally Posted by Grady
The red & white are most likely real thermostat wire. If I were a betting man, I would say the smaller R, G, Y, & Bk are telephone wire (std colors for phone wire). Doubling up on the phone wire amounts to a single thermostat wire, more or less.
So far so good, in doing what I mentioned earlier. I just don't get why telephone wire was used, foolish?

PS He added central air later on, and that has its own thermostat. I think I may just buy antoher digital for that too, too much to fish the AC thermostat wire to reach the Heat thermostat wire, or vice versa.

I've seen the wireless thermostats, woudl be nice if I could have 2 bases for the one remote.
 
  #6  
Old 12-27-05, 03:14 PM
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wireless

everything these days seems to be going wireless. I don't know why the hvac industry is so slow to respond. That would be a great idea! although I've never seen one.
 
  #7  
Old 12-27-05, 03:33 PM
airahcaz
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Originally Posted by hvac01453
everything these days seems to be going wireless. I don't know why the hvac industry is so slow to respond. That would be a great idea! although I've never seen one.
ya, guess I will stick to 2 thermostats on 2 walls for now. The digital Honeywells are popular, bought the 7 day, and the 5-1-1 (ebay had em cheap when I was looking for the second one)

wireless ones are at least 3 times as much, not sure worth it at this time, especially as I'd need to get 2

and thankfully, my AC thermo only has 3 wires whose colors match the back of the labeled thermostat!
 
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Old 12-27-05, 04:11 PM
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YOu can use one t-stat for both system.. Just make sure you read the install manual!
 
  #9  
Old 12-27-05, 04:14 PM
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look a little closer

Most tech's will run stat wire like 18/5 when only 18/3 is required because if for some reason a wire is open he has a spare. They are either cut back or wrapped around the brown jacketing. Most guys I know only run 18/8....even the one to the condenser that only uses 2 of the 8 wires...this way we only have 1 reel of stat wire in the truck to carry. Everything is about reducing the junk we have to carry. We stock 30 and 40 amp three pole contactors, when you only may need a 20 amp single pole or doublepole...We usually carry the 50VA multivolt tap transformers with circuit breaker instead of the 40VA without CB. If the secondary shorts out you can reset it, not replace it. So you might take a closer check of the wire to be sure. But those T87's are great, you just need the subbase with those switches...
 
  #10  
Old 12-27-05, 06:38 PM
airahcaz
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Originally Posted by Jay11J
YOu can use one t-stat for both system.. Just make sure you read the install manual!
my problem is the wires for each are not close to each other, and no opening in the walls that can help, unless i start breaking stuff
 
  #11  
Old 12-28-05, 01:05 PM
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the secret

is joint compound and paint....and maybe a hole to drill.
 
 

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