Honeywell T4398B1029/U Elec.Heat Thermost.HiPerf,Pr.Wht-Basebrd

It's double pole: switching action is DPST, single stage heat. That means both legs of the 240V circuit break when the thermostat is satisfied, and the Positive Off setting drops the heater completely. If your local code or the heater manufacturer requires two-pole disconnection, this one meets that; a single pole stat does not.

The T4398B1029/U mounts directly on a vertical 2 x 4 in. outlet box or on a 4 x 4 in. outlet box, and it's a vertical-mount unit only. The body measures 4-1/2 in. high x 2-7/8 in. wide x 2-5/8 in. deep (115 x 73 x 67 mm), so allow for the depth off the wall. It ships with a rugged plastic mounting base.

Yes. Honeywell states it replaces virtually all standard wall-mounted line voltage thermostats. Wiring is by 6 in. (150 mm) copper leadwires with color-coded leads, so it splices into an existing box rather than landing on screw terminals. The leads are suitable for connecting to aluminum wiring if an approved CO/ALR connector is used.

You can limit it. The T4398B1029/U comes with range stops to cap the adjustable span inside the 50 F to 80 F range, plus locking cover screws so the cover cannot be pulled off without a tool. The cover also carries a thermometer showing actual room temperature, which cuts down on the complaint calls in multi-family and hospitality work.

Setting range is 50 F to 80 F, with 1 C accuracy and a differential of 2 F (1 C). Ambient operating range is the same 50 F to 80 F (10 C to 25 C). The sensing element is a vapor filled dual diaphragm, which is what gives it the tight swing compared with a basic bimetal stat. If you need a setpoint below 50 F for freeze protection in an unoccupied space, this is not the right unit.

It carries both approvals: Underwriters Laboratories listing under File No. E4436, Guide No. XAPX, and CSA listing under File No. LR1322. That covers the usual spec requirements for US and Canadian electric heat installs.

The finish is Honeywell Premier White, the same finish used across the Tradeline line, so it blends with existing Honeywell wall controls in a standardized building. Exact match matters most on visible corridor and unit walls, so pull one and compare if your existing devices are older stock.

An outdoor sensor is available as an option for this thermostat. Honeywell also lists accessory 272804A/U for it. Order the accessory separately; it is not packed with the thermostat.