
Modulating Pressure Control
L91 Series
Modulating Controllers
Precision modulating and differential pressure controllers for stable industrial combustion and HVAC regulation.
Series Overview
The Honeywell L91 Series is a family of modulating and differential pressure controllers designed for applications requiring precise pressure regulation rather than simple on/off control.
This series is commonly used in combustion systems, HVAC control loops, and industrial gas applications where stable pressure modulation improves system efficiency and safety.
Functional Role in Control Systems
L91 Series pressure controllers are widely applied in:
- Modulating burner control systems
- Gas and fluid pressure regulation
- Differential pressure safety monitoring
- HVAC and industrial combustion control loops


Control Specs
- Modulating Control
- Differential Sensing
- Combustion Precision
Key Differences
Key Differences & Selection
L91 Series models differ primarily in:
- Control Logic: Options for Modulating pressure control vs. On/Off switching.
- Sensing Type: Differential pressure sensing vs. single pressure point monitoring.
- Integration: Designed for integration with burner management and combustion control systems.
- Precision: Varying levels of precision and adjustment ranges for specific industrial needs.
Applications
- Modulating burner control
- Gas & fluid pressure regulation
- Differential pressure monitoring
- HVAC control loops
- Industrial combustion safety
Model Comparison
Active Models
L91 Series Model Comparison
| Model | Control Type | Pressure Function | Typical Use |
|---|---|---|---|
| L91A1151/U | Modulating Control | Pressure | Combustion systems |
| L91A1177/U | Advanced Modulating | Pressure | HVAC & combustion |
| L91B1035/U | Precision Switch | Pressure | Gas & fluid monitoring |
| L91B1050/U | Differential Control | Differential Pressure | Safety applications |
| L91B1068/U | Pressure Monitor | Pressure | HVAC & burner control |
| L91B1241/U | Industrial Switch | Pressure | Wide applications |
Selection Guide
- L91A models: Preferred for modulating pressure control applications.
- L91B models: Used for precision monitoring or differential pressure safety.
- Integrated variants: Selected for complex gas or liquid pressure systems.
Need Precise Control?
Contact our engineering team for L91 Series modulating controller specifications.