Line Voltage baseboard heat with 24V relay


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Old 04-09-12, 01:45 PM
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Line Voltage baseboard heat with 24V relay

I'm replacing 30 year old thermostats on my line voltage baseboard heat system. The Great Room zone has two breakers feeding a White-Rodgers box which has the thermostat wire leaving it. Thermostat wire has red and white wire attached, green wire not attached. Old thermostat did not require a c wire but its replacement will. My question is how can I turn the available green wire into a c wire?

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Many thanks.
 
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Old 04-12-12, 05:51 AM
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Do you have a model # on this WR box?
 
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Old 04-12-12, 12:11 PM
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The model number on the label is 44-3012
but it is about 25 years old.

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Thanks
 
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Old 04-12-12, 01:09 PM
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The green wire from the transformer that is going to two white wire w/ wire nut. You can use that as your "C" hook up. So use the unused t-stat wire to that, and match that same wire to C at the t-stat.
 
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Old 04-13-12, 06:06 AM
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Thanks, I thought that may be the case. The output of the White-Rodgers unit is 18 v.a.c at .42 amps, and I'll likely use a modern low voltage thermostst (such as the Nest) which calls for 24 v.a.c (+/- 15%) at 100mA. Do you think the Nest's tolerances are as advertised and the 18 v.a.c won't be sufficient to power it, or a similar 24v unit?
 
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Old 04-13-12, 06:30 AM
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Take a voltag reading on it and see what it is putting out for voltage.
 
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Old 04-13-12, 06:56 AM
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Good idea. I do that by putting one probe on the green thermostat wire and the other probe on the white one? After connecting the green thermostst wire as you described below of course.
 
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Old 04-13-12, 07:04 AM
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Between Green and Red. You don't need to hook up the green t-stat wire yet. Just insert the probe into the wire nut.
 
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Old 04-13-12, 08:12 AM
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OK, now I'm making some progress, thanks to your generous help. My new multimeter tells me the circuit is putting out 25 volts. I think I have just one last question: When I connect my available green thermostat wire to the green wire coming out of the transformer do I add the green thermostat wire to the existing green/white/white (making it green/green/white/white in the wire nut) or do I remove the green wire coming from the transformer from the two white wires and have green/green in one wire nut and white/white in another?

Many thanks.
 
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Old 04-13-12, 12:12 PM
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Just wire the t-stat into the wire nut w/ the green, two white wires.
 
 

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