Living Room

Thermostats and the heaters they control: Resideo T-series, FocusPRO and PRO controls, tekmar zone controls, Suntemp electric baseboard, Reznor gas and hydronic unit heaters, Beacon Morris kickspace heaters and Midea heat pumps.

The specification to settle first is voltage, because it is the one mistake that destroys equipment. Low-voltage thermostats run on 24 V from the equipment transformer and control furnaces, boilers, air handlers and heat pumps. Line-voltage thermostats switch 120 or 240 V directly and are the only ones that work with electric baseboard and most kickspace heaters. The two are not interchangeable in either direction: a 24 V thermostat wired to a baseboard circuit will fail immediately, and a line-voltage thermostat will not run a furnace.

After voltage, match the stages. A control listed as 2 Heat / 1 Cool drives two heating stages and one cooling stage. Putting a single-stage thermostat on a two-stage furnace gives up the second stage entirely, and a heat pump needs a control that carries the reversing valve output on the O/B terminal — a conventional thermostat has no way to switch the system between heating and cooling.

Line-voltage models are rated in amps or watts. Confirm the heater’s load fits the thermostat’s rating before ordering, and where several baseboard sections run on one circuit, add the loads together.

Brands include Resideo, tekmar Control Systems, Suntemp, Reznor, Beacon Morris and Midea.