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Old 12-14-2014, 10:20 PM   #1
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Replacing low voltage thermostat


I have electric baseboard heat that is connected to a low voltage thermostat through a transformer/relay. From the wall there is 4 wires red, black, yellow and green. There are two screws on the back of the old thermostat and the red and black are connected to one and the yellow and green are connected to the other. I was expecting a red and white wire and maybe black for the c wire. How do I wire to the new thermostat?

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Old 12-14-2014, 11:22 PM   #2
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Replacing low voltage thermostat


How are these wired into the radiators? Is the old stat double pole, or is there different stages?

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Old 12-14-2014, 11:30 PM   #3
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Replacing low voltage thermostat


The old t'stat is just a temperature controlled switch. If you are going digital setback or nest give up a model number.
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Old 12-15-2014, 05:07 AM   #4
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Replacing low voltage thermostat


Need to change the low voltage wiring at the relay also if you want to use a digital thermostat that requires a common.

Post pic of wiring at relay.
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Old 12-15-2014, 06:26 PM   #5
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Replacing low voltage thermostat


I was planning on replacing the old thermostat with a zwave 2gig ct100. It's a vacation home so I'll post a pic of wiring at relay when I'm back up there.
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Old 01-19-2015, 07:55 AM   #6
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Replacing low voltage thermostat


So, can't for the life of me find the relay. Traced the low voltage wiring down to the crawlspace where it's supposed to be located but can't find it. So I guess my question is, without that pic of the wiring at the relay there's no way to tell how to wire the new thermostat? Any help would be greatly appreciated. Thanks.
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Old 01-19-2015, 08:29 AM   #7
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Replacing low voltage thermostat


Quote:
Originally Posted by Jpy52876 View Post
I have electric baseboard heat that is connected to a low voltage thermostat through a transformer/relay. From the wall there is 4 wires red, black, yellow and green. There are two screws on the back of the old thermostat and the red and black are connected to one and the yellow and green are connected to the other. I was expecting a red and white wire and maybe black for the c wire. How do I wire to the new thermostat?
Your system is a 2 wire system. They have simply doubled up the wire most likely because a 4 conductor cable was used and they had extra conductors.

The CT 100 I believe needs the common wire so you must have 3 wires at the stat. No problem because you have the extra wire run already... you have to find the transformer/relay though. If it was all original install then you will most likely find it at or near the main breaker panel. You *may* be able to hear with a cup against the wall it if all is quiet enough. Transformers usually (but not always) give off a quiet humming noise.
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Old 01-19-2015, 08:37 AM   #8
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Replacing low voltage thermostat


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Your system is a 2 wire system. They have simply doubled up the wire most likely because a 4 conductor cable was used and they had extra conductors.

The CT 100 I believe needs the common wire so you must have 3 wires at the stat. No problem because you have the extra wire run already... you have to find the transformer/relay though. If it was all original install then you will most likely find it at or near the main breaker panel. You *may* be able to hear with a cup against the wall it if all is quiet enough. Transformers usually (but not always) give off a quiet humming noise.
Thanks. The instructions with the CT100 say it can use a 2 wire system and use a battery. Would I still have to find the relay with that setup?
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Old 01-19-2015, 09:10 AM   #9
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Replacing low voltage thermostat


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Thanks. The instructions with the CT100 say it can use a 2 wire system and use a battery. Would I still have to find the relay with that setup?
If you can use a battery then no, finding the transformer/relay becomes irrelevant.
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Old 01-19-2015, 05:10 PM   #10
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Replacing low voltage thermostat


Be sure to change your batteries every year. It says a 2 year battery life. But why risk frozen pipes.

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