Thermostat Wiring Instructions not Matching NewThermostat Wiring Instructions not Matching New - I have a slightly older Rheem unit with the typical slide temp adjuster thermostat. I want to replace the old Thermostat with a digital, TP-N-721 from Vive Comfort that I have (not programmable, just digital. My current (old) thermostat is wired as such: Red - R | Blue - B | Green - G | Yellow - Y | Orange - O | White - W2 | Black - E | Brown - X. 8 Connections. The Terminal “L” on the old thermostat is not used.

The connections on the new TP-N-721 are. (one the left side of the base plate: C, O, B, E, and W2. Then on the right side of the base plate R, G, and Y. Here is what I can presume the new thermostat wiring will be, some are obvious: Red - R | Orange - O | Green - G | Yellow - Y | Blue - B | White - W2 | Black - E (That’s 7) but is this right and where does BROWN go? The only one left is “C”. . . Which should be “Common, which changes my presumption. I really do appreciate your help. Thanks!

Thermostat Wiring Instructions not Matching New

The answer is actually very simple. The brown wire will share the same termination as black or the emergency heating terminal. Emergency heat and auxiliary heating are the same thing and depending on the wiring and control share the same relay or sequencer to make it work. It is important to make sure you read the instructions whenever replacing the old thermostat with a new thermostat.

This information is often noted in the thermostat instructions so you can properly wire the new thermostat. All new terminations from the old thermostat to the new thermostat should be wired according to the instructions in the thermostat manual. We do provide a thermostat wiring color code page here to help you make the proper connections when wiring a new thermostat.

Heat Pump Thermostats - Thermostat Wiring Instructions not Matching New

Heat pumps have more terminations than an air conditioner with electric or gas heating has. This is because there are more controls in the heat pump. This is speaking strictly of air source heat pumps. You will also have more wires running to the heat pump condenser than you would an air conditioner with another type of heating source. Simply because air source heat pumps need a defrost cycle to defrost the condenser coils in the cold weather.

However, the wires running to the heat pump condenser will originate from the air handler. Some will come from the thermostat for the control but they will originate from the air handler. The wires running to the heat pump condenser, however, do not concern you to properly install this thermostat.

While not every single wire goes to the thermostat for control the system is set up to be controlled from the thermostat. Everything else, including defrost control, is done automatically based on other parameters. The control for this comes from control boards or control timers.

This all depends on the engineering of the heat pump system. It is very important for you to follow the thermostat wiring instructions as provided by the manufacturer. You can use this site to figure things out, to help you along the way. It is important though to follow the instructions for the thermostat you purchased.

Thermostat manufacturers also have help pages with detailed instructions for the thermostat you own. Simply use a search engine to find the instructions. Good luck and I hope everything works out for you.

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Thermostat Wiring Instructions not Matching New