WIRING DIAGRAM NOTES:

(Important, please read all notes before connecting wires)

•If the information provided in the following wiring diagrams does not clearly represent or match your system, please refer to the “TECHNICAL ASSISTANCE” section of this manual, and contact us before removing any of your existing thermostat wiring.

•All of the dashed wires shown in the wiring diagrams are either optional, or their usage depends upon your specific system type or brand. For example: Diagram #1 shows the fan wire as optional. If your system does not have a fan, than this terminal will not be used.

•Terminal letters shown in black represent typical wiring applications. Depending upon the brand of your specific system or thermostat, your terminal letters may not match exactly. Terminal letters shown in gray represent other possible wiring designations that you might see on your existing thermostat terminals.

•The optional “C” terminal is used for powering the thermostat by the 24-volt system, using the System Common wire. This can be used alone, or in addition to installing batteries as a backup. NOTE: connecting the System Common wire to the thermostat is not necessary for heating and cooling to function properly.

•If your old thermostat has both a “Y” and “C” wire both present, then “C” is most likely a System Common wire.

•For Heat Pump systems, you will use either the “O” terminal or the “B” terminal on this thermostat, but not both. If your old thermostat has both an “O” and a “B” wire present, then “B” is likely a System Common wire and may be connected to the “C” terminal. Connecting a System Common wire to this thermostat’s “B” terminal may damage the thermostat, and also your heating and cooling system.

•Some Heat Pump systems have a wire for AUX electric heat (usually W2), and also a separate wire for Emergency electric heat (usually E). This thermostat uses the W2 terminal for both AUX and Emergency Heat. Tape off your “E” wire, and confirm that all components function without it.

•If replacing an old thermostat that has a mechanical clock, there may be two wires labeled as “C” for the clock power. Tape off these wires and do not connect them to the “C” terminal of this thermostat.

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Lux Products P621U operating instructions Wiring Diagram Notes
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P621U specifications

The Lux Products P621U is a highly popular digital programmable thermostat that has garnered attention for its user-friendly interface and advanced features, making it a prime choice for homeowners looking to optimize their heating and cooling systems. With a sleek design and an array of functionalities, the P621U not only enhances energy efficiency but also ensures comfort in the home.

One of the main features of the P621U is its 7-day programmable schedule. This allows users to customize their heating and cooling settings for each day of the week, making it easy to align the thermostat's operation with their lifestyle. The ability to set different temperatures for weekday and weekend usage helps to minimize energy consumption when the house is unoccupied, ultimately leading to cost savings on utility bills.

The P621U employs 2H/2C heat pump technology, which facilitates the management of both heating and cooling systems efficiently. This dual-stage capability ensures that the thermostat can adapt to varying temperature demands, delivering optimal comfort year-round. Additionally, the thermostat is compatible with a wide range of HVAC systems, including conventional heating and cooling, heat pumps, and even gas or electric systems.

Another standout characteristic of the Lux Products P621U is its intuitive touchscreen display. The large, backlit screen is easy to read and navigate, allowing users to quickly adjust settings or check the current temperature. The user-friendly interface promotes a hassle-free experience, and the straightforward programming process means users can set it up with minimal effort.

The thermostat also features an auto changeover function that automatically switches between heating and cooling modes based on the temperature settings. This adaptive technology ensures that users experience consistent comfort without the need for manual adjustments. Moreover, the P621U includes a battery backup system, which preserves settings during power outages, ensuring uninterrupted operation.

The Lux Products P621U also comes equipped with an energy-saving mode, which encourages users to adopt energy-efficient practices. By allowing users to set eco-friendly temperatures, the thermostat not only helps maintain a comfortable environment but also promotes sustainability.

In summary, the Lux Products P621U is a sophisticated yet simple solution for modern heating and cooling management. With its programmable capabilities, dual-stage technology, intuitive interface, and energy-saving features, it provides a balance of comfort, convenience, and efficiency that can significantly enhance any home environment.
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