Tag: RTH111

Honeywell RTH111/RTH221 Programmable and Non-programmable Thermostats Installation Guide Introduction The RTH111/RTH221 thermostats can be used to control: a gas, oil or electric furnace — 2 or 3 wires a central air conditioner — 2 or 3 wires a hot water system (steam or gravity) with or without pump — 2 wires a millivolt system —…