Resideo T498A1778/U Electric Heat Thermostat with Gold Baseboard

Item #: HONE-T498A1778/U
Mfr. part #: T498A1778/U

Key specifications

System typeLine voltage
Voltage120/208/240/277 Vac
Max load22 A resistive
SwitchingSPST
ProgrammableNo

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$56.11

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Shipping details

Shipping weight: 0.47 lb
Box size: 4.75 × 3.25 × 3.2 in

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Brand	Resideo
Manufacturer part #	T498A1778/U
Supply Voltage	120 Vac; 208 Vac; 240 Vac; 277 Vac
Frequency	60 Hz
Electrical Connections	6 in. (150 mm) black and red leadwires
Electrical Ratings	Non-inductive resistive 22A at 120/208/240 Vac. 19A at 277 Vac.
Ambient Temperature	40 F to 80 F
Mounting	Vertical
Application	Electric baseboards, convectors and fan forced heaters (resistive rated loads).
Includes	Range stops, locking cover and extra knob decal for recalibration
Dimensions	4 9/16 in. high x 2 7/8 in. wide x 1 15/16 in. deep
UL	Listed; File No. E4436, Guide No. XAPX
CSA	Listed: File No. LR1322
Stages	1 Heat
Customer Special	Robert Gordon
Color	Brush gold finish
Sensor Element	Bimetal
Accuracy (F)	1 F
Differential Temperature (F)	3 F
Switching Action	SPST
Setting Temperature Range (F)	40 F to 80 F
External Sensors Available	Outdoor Sensor optional

T498A1778 has been discontinued by the manufacturer (2026-08). No direct replacement has been published by the manufacturer. Contact us for help choosing an alternative.

The T498A1778 is a line-voltage thermostat from Resideo (Honeywell Home) for electric resistance heat — baseboard, convectors, radiant ceiling or panel heaters.

Line voltage is the distinction that matters here. A low-voltage thermostat switches a 24 V control circuit and lets a furnace or boiler do the work; a line-voltage thermostat carries the full heater current itself. They are not interchangeable, and a low-voltage stat wired to a baseboard circuit fails immediately.

Match the voltage and the pole configuration to the heater circuit, and check the amperage of the heater against the rating of the thermostat. A thermostat sized below the load is the most common cause of a line-voltage stat failing in its first season.