Question about Honeywell Electronic Programmable Heat/Cool Thermostat - CT3300A100 Heater

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Help - I am trying to install a honeywell RLV4300A

I have removed my existing old thermostat. Into the old thermostat there are 2 white wires and 1 black wire (from the old therm.) connected. Then there are 2 black wires and 1 red wire (from the old therm.) connected. Then the remaining 1 black and 1 red wire (from old therm. are connected to a single black and single white wire from box.

How do I reconfigure that to attach to the 2 black wires on the new therm.?

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  • Anonymous Jan 17, 2009

    I have the same problem but, my old system has just 2 wires one is white the other is black. But in new termustat has 5 diferent



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You will have to have schematics from the old wiring diagram. Then you will have to confirm its consistency with actual old wiring before you can be sure that the wires run to the proper places on the old heater and a/c system. This sounds like a gas furnace and is simpler than a heatpump. Once you know what distinguishes the wires with the same color, you should label them and then you may call them a different color if they were wired with wrong wire colors. You may be in luck if you go to the furnace control box an look at the terminals.. They are usually labeled with a R for Red and W for white and Bl for Blue and B or Black. If you have other colors on these then it sounds that it was wired with wire spare wire by someone who knew what they were doing but neglected to leave a path for someone else follow.
You may be able to use a continuity tester of circuit tester to id these wires that are in question...
ie, once indintified, you can match with the requirements of the new stat.

Posted on Jan 13, 2009


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GE Timer #15086 has red, white, green, black wires. Wall has white, black & black wires and switch sits between 3 other light switches. (I am replacing the current timer which only has 3 wires and...

GE 15086 programmable timer replaces single-pole switch only.
Single pole means 1 device turns Load on-off.
3-way is where 2 devices turn Load on-off, for example 2 switches located in hallway.

Your existing timer has white, black and blue wires.
Your new timer has white, black, red and green wires.
Green wire connects to bare ground wire in every occasion with every wiring device.

Electricians don't guess, they test the other wires.

Remove old timer.
Separate wires for testing.
Turn on power.
Tape ordinary tester leads to wood sticks to keep hands away from power.
Test each wire to bare ground wire.
Tester will light up on Hot wire. The Hot wire will connect to timer black wire.
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Tester will light up on Neutral wire. Neutral wire connects to timer white wire.

The remaining wire connects to timer red wire.
After connecting timer, push manual override button to check that Load turns on-off.

Manual override on 15086 is the door that covers buttons > use door as push button to check Load.
Next, program the timer.
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You can also take advantage of Fixya phone support. Expert will walk you through the steps for a price.

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Review old switches:
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New Leviton double-rocker switch:
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We need to identify Hot wire.

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