103 thermostats and thermostat accessories from Resideo, tekmar Control Systems, Southwire and DiversiTech. Resideo is the company that builds and sells the Honeywell Home line, so the thermostat marked TH6220WF on the invoice is the one sold at retail as the Honeywell Home T6 Pro — same part, two names. Families stocked here: PRO 1000, PRO 2000, PRO 3000 and CommercialPRO 7000; the T-series from T1 Pro through T10 Pro; FocusPRO 5000 and 6000; VisionPRO 8000; WiFi 9000; and Prestige IAQ.
Voltage decides the thermostat before anything else does. A low-voltage thermostat runs on 24V through the equipment transformer and is what gas furnaces, heat pumps, boilers and air handlers use. A line-voltage thermostat switches 120V or 240V directly and is for electric baseboard, electric radiant panels and fan-forced wall heaters. They are not interchangeable. Wiring a 24V thermostat to a 240V baseboard circuit is a fire risk, not a malfunction, and the mistake is easy to make because the two look alike on the wall.
Fifteen line voltage thermostats are stocked for electric heat, single-pole and double-pole, manual and 7-day programmable. Single-pole leaves one leg energized when the dial is off; double-pole breaks both. If the heater has to be fully dead at the thermostat, it has to be double-pole.
Millivolt is the third case and it catches people out. A standing-pilot wall heater or gas fireplace generates its own 750 mV from the thermopile and has no transformer at all; it needs a millivolt-rated thermostat, and a digital 24V unit will simply not close the circuit. Heat-only millivolt models are stocked for exactly this.
The C-wire is the most common reason a Wi-Fi thermostat replacement stalls. Older homes were wired with four conductors and no common, and a smart thermostat needs continuous 24V to run its display and radio. Either pull new cable or add an adapter — the Resideo WireSaver THP9045A1023 puts the common back at the equipment end without opening walls.
Resideo splits connected control two ways and they solve different problems. Wi-Fi models talk to the house router and the phone app: T6 Pro Smart, the Wi-Fi VisionPRO 8000, and the WiFi 9000 colour touchscreen. RedLINK is Resideo’s own 900 MHz link between the thermostat and its own accessories — wireless indoor and outdoor sensors, equipment interface modules, remote modules and the TrueZONE adapter — and it works where there is no reliable Wi-Fi at the equipment. Eight RedLINK modules and sensors are stocked. The T10 Pro and Prestige IAQ kits use both.
Five Southwire thermostat wire runs are stocked in 18/2, 18/4, 18/5 and 18/6, in 250 ft and 500 ft. Count the conductors against the system before ordering: a straight heat-cool job lives on four, a heat pump with auxiliary heat and a common wants six, and pulling the smaller roll is how a job ends up needing a C-wire adapter later.
The range breaks down as: non-programmable thermostats (27), thermostat accessories (19), programmable thermostats (17), line voltage thermostats (15), smart and Wi-Fi thermostats (9), thermostat wire (8), RedLINK modules and sensors (8). Accessories cover cover plates for the PRO, FocusPRO, T-series and Prestige, thermostat guards and keys, remote indoor and outdoor sensors, and a 120V transformer.
Related: the full Resideo (Honeywell Home) catalog, connected home equipment, thermostatic radiator valves for room-by-room hydronic control, and heating controls.
