Asked by: Xeber Wolfli
asked in category: General Last Updated: 5th March, 2020

What is a thermostat relay?

The two transformers provide the power the thermostat uses to switch on the various relays. The relays in turn switch on the power to the fan and the air conditioner or furnace. Let's see how this power flows through the thermostat when the air conditioner is running.

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Similarly, you may ask, what does the thermostat do?

Its job is to block the flow of coolant to the radiator until the engine has warmed up. When the engine is cold, no coolant flows through the engine. Once the engine reaches its operating temperature (generally about 200 degrees F, 95 degrees C), the thermostat opens.

Also, how does a 3 wire thermostat work? In the most basic system, this functionality is provided by use of a fan center relay, and the low voltage wiring to the thermostat now will require a minimum of three wires (for heat only units) and four wires (for heat / cool / fan) for control. This additional terminal is labeled 'G' in the thermostat.

Subsequently, one may also ask, where does the power to the thermostat come from?

Most room thermostats on heating and cooling systems receive their 24V DC electrical power from a low voltage transformer that itself is usually found at the boiler or furnace (blue arrow in our photo at left).

How do thermostat wires work?

Power from the air-conditioning transformer comes into the terminal labeled RC. The ball controlled by the mode switch jumps the current onto a trace that leads to the terminal in the lower-right corner of the circuit board. This terminal connects to the top layer of the thermostat through a screw.

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