This manual describes how to install and use the Honeywell RTH7400D thermostat.
This guide explains how to install and set up the Honeywell RTH7400D programmable thermostat. It includes a checklist of required parts, tools, and batteries, as well as step‑by‑step instructions for removing the old thermostat and mounting the new wallplate.
The manual also covers important wiring precautions, special instructions for C and C1 wires, and the one‑year limited warranty terms. Follow the instructions to ensure safe and correct operation of your heating and cooling system.
| Control voltage | 24 Vac (heating/cooling) or 750 mV (heating) |
|---|---|
| Power source | Two AA alkaline batteries |
Check that the required items, tools, and batteries are included before starting the installation.
Do not connect the wires to the new thermostat based on wire color; use the supplied wire labels instead.
Do not place the old thermostat in the trash; follow local waste‑management instructions for recycling a sealed‑tube mercury thermostat.
Honeywell provides a limited one‑year warranty from the date of purchase.