Honeywell L6191B2070U aquastat

Aquastat (thermostat) Honeywell L6191B2070U is a specialized dual immersion thermostat designed for heating and hot water systems. The device combines two independent functional modules in one housing: a temperature controller and a safety limit with manual reset. Technical specifications Parameter Value Part numbers L6191B2070U, 534.109.021 Manufacturer Honeywell Mounting type Immersion (with common stem) Sensor type Liquid, two independent Working medium Water Protection class IP40 Module 1 type (Controller) Working temperature control Module 2 type (Limit) Limit thermostat with manual reset Key advantages Dual design: Combines the functions of a working thermostat and an emergency limit, saving space and simplifying installation compared to installing two separate devices. Manual reset of limit: In case of emergency overheating, the circuit opens, and to restart, the reset button must be manually pressed. This ensures that the cause of overheating is eliminated before system operation resumes. High-precision liquid measurement: Liquid-filled sensing elements provide fast thermal response and high accuracy compared to bimetallic alternatives. High switching capacity: Electrical switches are rated for direct connection of circulation pumps, contactors, and gas valves without intermediate relays. Operating principle and application The aquastat is installed directly into the heat exchanger well of a boiler or water heater. Temperature controller: Maintains the set working water temperature by controlling the pump or fuel supply valve. Limit (Manual Reset): Acts as a safety device. If the coolant temperature exceeds the set