Honeywell, L8148E1265/U, Aquastat Relay

Honeywell L8148E1265 Aquastat Relay – High Limit Controller for Hydronic Heating Systems

The Honeywell L8148E1265 is a high-limit aquastat relay designed for use in hydronic heating systems requiring control of both circulator and burner operations. This controller is engineered to provide high-limit temperature protection and line-voltage switching in oil-fired and gas-fired boiler applications with a 24V thermostat interface.

This model includes a factory-installed immersion well adapter tube and is suitable for vertical mounting. It provides a non-adjustable 15°F fixed differential and is commonly used in systems requiring high-limit cut-off at temperatures between 180°F and 240°F.

Application Details

• Control Function: High-limit temperature control with burner circuit interruption
• Primary Voltage: 120 VAC line voltage
• Thermostat Input: 24V
• Circuit Type: SPST relay with transformer for low-voltage control circuit
• Differential: Fixed at 15°F

Technical Specifications

• Temperature Range: 180°F to 240°F
• Mounting Orientation: Vertical (horizontal case mounting option available)
• Insulation Depth: 1-1/2" to 3"
• Humidity Tolerance: 0–95% RH (non-condensing)
• Compatible with: Hydronic heating boilers using immersion-type temperature sensors

Installation Guidelines

Installation must be completed by qualified personnel familiar with line-voltage wiring and boiler control systems. The unit is designed for direct immersion well installation and should be wired according to local code and system requirements. Always verify burner circuit wiring, transformer loads, and thermostat compatibility before energizing.

Contractor Notes

The L8148E1265 is part of Honeywell's TRADELINE® series and includes essential installation accessories such as a well adapter tube and thermal conductive compound. It is a direct replacement for a wide range of standard aquastats used in residential and light commercial hydronic boiler systems.

Additional Features

• High-limit opens burner circuit only; circulator continues to operate
• Low-voltage terminals for integration with remote controllers
• Enclosed SPST relay for burner control with integral 24V transformer