Honeywell Home T4398A1021/U Electric Heat Thermostat HiPerf, Premier White®-Baseboard

The T4398A1021 is a non-programmable thermostat from Honeywell Home.

A non-programmable thermostat holds one setpoint until someone changes it. That is the whole design, and it is the right design more often than the market admits: in a shop, a rental, a spare room or anywhere occupancy has no schedule, a programmable stat gets overridden permanently within a week and then behaves like this one with extra steps.

This is a line-voltage thermostat for electric resistance heat. It carries the heater current itself rather than switching a 24 V control circuit, and it is not interchangeable with a low-voltage stat.

Where it hangs decides what it reads. A thermostat measures the air touching it and nothing else, so an interior wall about five feet up, out of direct sun, away from supply registers and doorway drafts, and clear of the back of a wall carrying hot water or flue pipe. Most complaints that a stat is “off by three degrees” are placement, not calibration — the stat is reading the truth about a spot nobody lives in.

Confirm the system type before ordering — low voltage, line voltage and millivolt thermostats look similar and are not interchangeable.

• Brand: Honeywell Home
• Manufacturer Part #: T4398A1021/U
• Type: Non-programmable thermostat
• System: Line voltage
• Shipping weight: 0.5 lb
• Category: Thermostats