Wifi thermostat: compatibility with stack control

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Old 11-27-17, 05:29 PM
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Question Wifi thermostat: compatibility with stack control

I'm considering getting a Wifi Thermostat if I manage to find one on sale but am unsure if my current system can handle it.

My original thermostat wiring was shoddily done, draping across the crawlspace and running along the face of the wall, barely having the length to reach the thermostat. I've replaced the wire with a 5 conductor one and rerouted it for future expand ability.

Current, My setup is using two wires which to my understanding isn't enough to power most wifi thermostats and based off my research lacks a common wire? I have a Honeywell RA116A1063 and the wiring is currently connected to the W(T) and B(T) terminals on the stack control. There is an unoccupied R terminal.

Is it possible to provide a common with this setup, and what's the unoccupied R terminal provide that the W(T) and B(T) do not?

Thanks!
 
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Old 11-27-17, 05:37 PM
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The additional wire (third terminal) from that control goes to the heat anticipator inside certain old thermostats. This system is basically not used anymore.

You cannot run a wifi thermostat directly from that control.
You would need to supply your thermostat with a dedicated 24vac power supply. It could be a plug-in wall wart or a transformer on a plate. You would use 4 wires between the stat and the furnace.

Rc and C to the 24vac supply.
Rh and W (W1) to the stack control.

Example of wall transformer..... and there are many available.
24-Volt-AC-Adapter-RE2440TF/203193109

Example of transformer on a plate.... and again there are many.
Sloan-EL154-24-Volt-Plate-Mount-Transformer-0345154PK/202933115
 
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Old 11-27-17, 05:52 PM
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Thanks! The plate option and then splicing it at the stack control would probably do the trick.

On a side note, Is there a specific wire coding for oil furnace stack controls?

I replaced it exactly as it was when I ran the new cable but question the color of the wires that were used when moving away from 2 conductor cable.

Currently, the red wire is connected to the W(T) and Blue wire to the B(T) leads.
 
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Old 11-27-17, 05:55 PM
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Common heating colors are red and white.
In your application... the colors you choose are fine.

The transformer on a plate is also available from amazon.
amazon/Emerson-S84A-410-Class-2-Transformer/dp/B000CCSIUA

This one mounts to the side of an electrical box.
amazon/Functional-Devices-TR50VA001-Transformer-Threaded/dp/B008HOV28A

Needs to be 24vac and at least 10va.
 
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