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hvac - How do I connect a WiFi thermostat to my furnace's primary control? - Home Improvement Stack Exchange
![electrical - Old oil furnace with 2 wire thermostat, installing new wifi and need C wire. How can I wire with my current stack switch? - Home Improvement Stack Exchange electrical - Old oil furnace with 2 wire thermostat, installing new wifi and need C wire. How can I wire with my current stack switch? - Home Improvement Stack Exchange](https://i.stack.imgur.com/Hq7vG.jpg)
electrical - Old oil furnace with 2 wire thermostat, installing new wifi and need C wire. How can I wire with my current stack switch? - Home Improvement Stack Exchange
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