Honeywell C36TR1UA1000 Mechanical Thermostat
The Honeywell C36TR1UA1000 is a classic round thermostat designed for residential and light commercial HVAC systems. It provides reliable temperature regulation using a proven bimetal sensing element, requiring no external power for its basic operation.
Core Technical Features
Temperature range: 10°C to 30°C (50°F to 86°F) with an accuracy of ±1°C. The switch action is single-pole double-throw (SPDT) with a voltage rating of 24 VAC and maximum current of 1 ampere. The differential (hysteresis) is factory set to 0.8°C, preventing short cycling of compressors. The housing diameter is 75 mm, depth 35 mm, and it is constructed from flame-retardant ABS plastic.
Installation and Wiring
Mounting is accomplished using two M3 screws on a standard 75x75 mm junction box or directly to drywall with supplied anchors. Wiring terminals accept solid or stranded copper conductors from 0.5 to 1.5 mm². The C36TR1UA1000 supports two-wire heat-only or three-wire heat/cool changeover systems when used with a separate fan relay. A built-in leveling bubble ensures proper orientation for bimetal operation.
Operating Principle
A bimetal coil expands and contracts with temperature changes, rotating a mercury-free switch contact. This mechanical design eliminates battery replacement and ensures decades of service life. The setpoint adjustment knob has tactile detents at 1°C intervals, and an integrated thermometer shows ambient temperature. The unit is compatible with gas furnaces, oil burners, electric resistance heat, and single-stage cooling systems with external contactors.
Applications and Limitations
Ideal for retrofitting older HVAC controllers where digital complexity is unnecessary. Not suitable for heat pump systems requiring reversing valve control or for multi-stage equipment. The thermostat is rated NEMA 1 for indoor use, avoiding condensation or direct water exposure. For maximum accuracy, installation on an interior wall away from drafts, sunlight, and heat sources is recommended.
Regulatory Compliance
The C36TR1UA1000 meets UL 873 and CSA C22.2 No. 24 standards. The product is mercury-free under RoHS, and packaging is recyclable. No calibration is required after installation; however, annual cleaning of the bimetal coil with compressed air prevents dust accumulation that could affect sensitivity.
Summary
For straightforward temperature control without batteries or digital programming, the Honeywell C36TR1UA1000 offers simplicity, durability, and precise mechanical response. It remains a preferred choice among HVAC technicians for legacy system replacements.
