High Limit Triple Horizontal Mount Aquastat Relay, 10 Degree F High, 10-25 Degree F Low

Honeywell L8124L1011/U – Triple Aquastat Relay, Horizontal Mount, 24V

The Honeywell L8124L1011/U is a combination high limit, low limit, and circulator control designed for hydronic heating systems that incorporate domestic hot water service. It is suitable for use with oil-fired or gas-fired boilers operating with immersion well sensors. The control provides temperature regulation, circulator control, and burner cut-off based on system demand and operating limits.

This model is configured for horizontal immersion mounting and includes a diaphragm-type powerhead for reliable temperature response. It operates on a 24 VAC control circuit and supports multiple zoning configurations when used with additional relays or zone valves.

Core Functions

• High Limit Function: Interrupts burner operation when water temperature exceeds setpoint, protecting the boiler from overheating.
• Low Limit and Circulator Control: Maintains boiler temperature for domestic hot water priority and controls the circulator accordingly.
• Horizontal Mounting: Designed for horizontal immersion wells; requires 3-inch insertion depth for proper sensor contact.
• Multi-Zone Capability: Compatible with multi-zone heating systems using additional relays or zone valves.
• Control Voltage: Operates on standard 24 VAC for integration with low-voltage HVAC control circuits.

Technical Specifications

• Temperature Setpoint Range: 130°F to 240°F
• Differential Adjustment: 10°F to 25°F
• Humidity Tolerance: 0 to 95% RH (non-condensing)
• Voltage: 24 VAC
• Mounting Orientation: Horizontal only
• Well Requirement: Fits 3" immersion wells (sold separately)

Installation Considerations

Installation should be performed by qualified HVAC personnel familiar with hydronic boiler control wiring. Proper wiring and limit setting are critical to ensure both safe operation and domestic hot water availability. Always verify compatibility with system wiring diagrams and consult manufacturer documentation for configuration guidance.

Application Notes

• Used in hydronic heating systems with tankless coil domestic hot water
• Provides burner cutoff at high limit and circulator operation based on temperature control logic
• Compatible with Honeywell Tradeline® accessories and alternate zone control modules