Honeywell RTH7600D thermostat does not work without batteries


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Old 12-26-14, 12:09 PM
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Question Honeywell RTH7600D thermostat does not work without batteries

I installed a new Honeywell RTH7600D thermostat since my older Honeywell Chronotherm IV Plus kept losing power frequently and needed the time/day to be set every time. After installing the new thermostat, I noticed that it does not work without the batteries inside. This does not seem right as the batteries are meant as backup only, correct? What could be the problem? I have matched the wires (R-R, W-W, Y-Y and G-G).
Thanks,
Ram
 
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Old 12-26-14, 12:32 PM
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Batteries are optional when you connect a 5th wire to C at the stat and furnace.
 
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Old 12-26-14, 01:45 PM
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There is no 5th wire. Besides, the previous tstat (Honeywell chronotherm iv plus) worked without any wire going to C or batteries. I get 24 V between R and G and I thought the tstat woulf use this, no?
Thanks,
Ram
 
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Old 12-26-14, 02:32 PM
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You want the digital thermostat to function without AC power or DC power?

How will it get power?

Post the model number of the old thermostat so that we can look up the manual.
 
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Old 12-26-14, 06:14 PM
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Sorry if I am causing confusion. I am wondering if the new tstat (Honeywell rth7600d) should function without batteries like the old one did? The old one was a Honeywell chronotherm iv plus, model T8600D.
Thanks,
Ram
 
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Old 12-26-14, 06:42 PM
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https://customer.honeywell.com/resou...0s/68-0164.pdf

Yep, it looks like they did have a power stealing option. I had an old Chronotherm 4 that I replaced 10 years ago that used a C terminal.

I had a Chronotherm 2 two stats before it that also used a C terminal.

I have not had your luck with power stealing thermostats. I usually pull wire if enough conductors are not available.

The new stat requires C or batteries.
 
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Old 12-26-14, 06:46 PM
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Based on the techlit on your old thermostat it was what's called a power stealing thermostat. It siphoned off a little bit of power thru the heating/cooling relays.

honeywell resources TechLitDocuments 68-0164.pdf


Your new thermostat is going to require a source of 24v thru a C connection or batteries.
 
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Old 12-26-14, 07:44 PM
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I'll just run it on batteries since there were only 4 wires, R, W, Y and G and they all connected. Thanks for checking and your advice Houston204.
 
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Old 12-27-14, 06:48 AM
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Since I do not see a C connector, I will run it on batteries and see how long they last. Thanks Pete.
 
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Old 12-27-14, 08:12 AM
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That thermostat will run quite a while on a set of batteries. The back light in the thermostat is a power eater.... luckily it shuts off after pressing a button.
 
 

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