Old Honeywell to Honeywell RTH2300B Help needed

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Old 02-10-13, 03:01 PM
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Old Honeywell to Honeywell RTH2300B Help needed

I'm trying to replace my very old but still working Honeywell thermostat with a new RTH2300B. The existing (old) unit has marking for the five wires but they dont seem to align with the new letters. I'm attaching a picture for reference.



The left two wires appear to be labeled "TR" and when using my 110v tester show as hot. The right three wires are labeled as follows... center red wire is "W", next wire going clockwise is the green wire and is labeled "B" and the last wire on the right has no visible label on the board and is a white wire. The three right wires seem to travel together from the basement and are hooked directly to the boiler, the white wire looks to be not in use. I cant seem to locate where the two hot wires are attached to in the basement, I can trace the wires all the way until about 5 feet from the boiler then they disappear in the basement ceiling.

I tried to call Honeywell but without having letter codes they can reference they wouldn't recommend any action and said to call a proff installer.

I'm plenty savvy enough to connect it up but cant figure out where to start with matching which wires to which new connection.
 
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Old 02-10-13, 07:53 PM
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Do you have any model# on the old stat?
 
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Old 02-11-13, 06:06 AM
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You said the left wires are hot.... what voltage did you read there? It almost looks like a old programmable sub base wiring. The left wires were used to power a clock and the right wires were used for a series 20 controller. However, it could be for series 10 also. What we really need to know, so we are not just guessing, is more info about your heating system and what terminals the wires land on inside your heating system.
 
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Old 02-11-13, 02:43 PM
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Hmmm, I checked that old thermostat EVERYWHERE and not a model # to be found. Would a picture of the face itself help at all? There is a clock on it though. I cant find my meter but I have a tester that detects between 50-250v and it triggers when hitting the two lines on the left and notta for the center and right wires.

I can take a look at where the wires run to in the boiler itself and reply back shortly.
 
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Old 02-11-13, 02:59 PM
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yes, pictures are good, find out where they go to the boiler, and get a meter!
 
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Old 02-16-13, 08:43 AM
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Talking

It appears the red wire on the right goes to R on the boiler and the green wire on the right goes to G on the boiler.



Splice from the boiler to the wires run in the home below.



Sounds like I should connect the red wire on the right side to the R terminal and the green wire on the right side to the G terminal.
 
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Old 02-16-13, 09:58 AM
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So it seems that doesnt work, when I connect the Red to R and the Green to G the boiler starts when I switch the fan into the "On" position instead of auto. As for voltage, it appears that I get the following:

Left White 40 volts
Left Red 60 volts
Center Red 20 volts
Right Green 20 volts
Right White 0 volts

It also appears at some point my futzing around took out the display on the new thermostat so back to Depot that will go, I plan to get the same model unless there's reason to get a different one.
 
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Old 02-16-13, 10:00 AM
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No, that is not what it seems. You have a fan center that is being used to turn on the pump and the boiler, that is why it goes to G. So, on the new thermostat, do NOT use either of the wires on the LEFT side of the old thermostat; wire nut and tape off and stick in wall. Right side of old thermostat wires goes RED to R and Green to W and White is not used
 
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Old 02-16-13, 10:04 AM
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How are you testing these wires? Where are you putting the meter leads? I would like you to test with your meter leads on both wires on the left side, I know what voltage you should get on the right side. I recommend a better Honeywell thermostat than RTH2300B. A good thermostat is at least $70.
 
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