Description
Heat Pump Flow Setter, Balancing Valve 1″ Male – 5–42 L/min
The 1″ Male Heat Pump Flow Setter is a practical flow regulation and measurement component designed for use in compatible air source heat pump (ASHP), underfloor heating and hydronic heating systems.
Maintaining the correct water flow rate is essential for efficient heat transfer and reliable system performance. This adjustable flow setter provides a measurement range of 5–42 litres per minute, allowing heating engineers to monitor circulating water flow and adjust the system according to its design requirements.
The integrated flow indicator provides a convenient visual reading, making the valve particularly useful during system balancing, commissioning, servicing and troubleshooting.
Key Features & Benefits
- 5–42 L/min Flow Range – Allows water flow measurement and adjustment.
- 1″ Male BSP Connection – Suitable for compatible threaded heating pipework.
- Built-In Flow Indicator – Provides a visual indication of the circulating water flow.
- Heat Pump Compatible – Suitable for appropriately designed air source heat pump installations.
- Underfloor Heating Applications – Can be used in compatible wet underfloor heating systems.
- System Balancing – Helps installers achieve the required water flow rate.
- Commissioning & Maintenance – Useful for checking and adjusting flow during installation and servicing.
Technical Specifications
| Specification | Details |
|---|---|
| Product Code | ZL-FS28-42L |
| Product Type | Flow Setter / Flow Regulating Valve |
| Connection | 1″ Male BSP |
| Nominal Bore | DN20 |
| Flow Range | 5–42 L/min |
| Pressure Rating | PN10 |
| Maximum Continuous Temperature | 120°C |
| Kvs | 2 |
| Installation Orientation | Horizontal or Vertical |
| Applications | ASHP, Heat Pumps, Wet Underfloor Heating |
Suitable Applications
- Air source heat pump (ASHP) installations
- Ground source heat pump systems
- Wet underfloor heating circuits
- Low-temperature heating systems
- Domestic and light commercial heating
- System commissioning and flow balancing
- Heating system maintenance and replacement work
Why Use a Flow Setter?
Correct water flow is particularly important in heat pump systems, where circulation rates must meet the manufacturer’s specifications to ensure effective heat transfer.
The ZL-FS28-42L allows installers to check and regulate flow through the heating circuit, helping achieve accurate hydraulic balancing and consistent system operation.
Its built-in indicator also makes it easier to verify flow rates during servicing without relying solely on external measuring equipment.
Installation Note: Always confirm the required flow range, connection compatibility and installation requirements before fitting. Flow settings should follow the heat pump manufacturer’s specifications.





