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The next generation of pumpless pressurisation has arrived. Building on the proven success of Mikrofill 3, the new Mikrofill 3 PRO is raising the benchmark for pumpless pressurisation systems. Engineered for superior serviceability, smarter diagnostics and PRO performance, it delivers reliable pressure management while simplifying compliance, monitoring and maintenance for modern heating and cooling systems.
Raise the Bar with the NEW Mikrofill 3 PRO
The Mikrofill 3 PRO is a WRAS-approved, fully automatic, sealed-system filling device designed to maintain pressure in commercial heating and cooling systems. It combines intelligent control with high-performance specifications to ensure efficient pressure maintenance and full regulatory compliance in a compact, wall-mounted design.
Mikrofill 3 PRO Key Specifications
- WRAS Category 4 backflow protection: WRAS Approval number 2307805
- 3.95-inch full-colour LCD interface: Clear, intuitive setup, diagnostics and system monitoring.
- Electronic pressure management: Automated pressure control for heating and chilled systems.
- Flow monitoring and volume logging: Accurate flow rate and fill volume measurement.
- Smart fault logic and leak detection: Patent-pending diagnostics for faster fault identification.
- Large event logging capacity: Records up to 100 parameter changes and fault events.
- MODBUS RTU and BMS outputs: Four customisable outputs for full system visibility.
- TM65 embodied carbon calculation: Data calculated in accordance with CIBSE TM65:2021.
- Compact wall-mounted design: Measuring 290 mm (H) x 250 mm (W) x 155 mm (D).
Introducing the Mikrofill 3 PRO pumpless pressurisation system
The Next Evolution in Pumpless Pressurisation
Building upon the proven success of the original Mikrofill 3, the PRO model introduces significant upgrades to performance, diagnostics, and connectivity. These advancements provide engineers and contractors with more data, easier servicing, and higher pressure capabilities.
Mikrofill 3 PRO vs Mikrofill 3:
- NEW Smart Fault Logic: Patent-pending, advanced diagnostics identify faults earlier, helping improve reliability and reduce system downtime.
- Increased pressure capability: The PRO increases inlet pressure from 5 to 9 bar and cold fill pressure from 4.7 to 8.7 bar, widening compatibility with higher-pressure systems.
- Improved fill volume monitoring: Flow sensors provide measured fill volume and waste data, replacing the estimated indicator used in the original unit for clearer system insight.
- Improved BMS connectivity: The PRO introduces MODBUS RTU communication, enabling seamless system monitoring and fault alerts through building management systems (BMS).
- Upgraded unit protection: Upgraded from IP20 to IP55 through a new sealed enclosure design for improved reliability in plant room environments.
| Feature | Mikrofill 3 | Mikrofill 3 PRO |
| Max Inlet Pressure | 5.0 bar | 9.0 bar and stable water pressure across floors |
| Max Cold Fill Pressure | 4.7 bar | 8.7 bar |
| IP Protection Rating | IP20 | IP55 |
| Smart Fault Logic | No smart fault logic | Smart fault logic |
| Fill Volume | Estimated | Measured |
| BMS Communications | 3 volt-free contacts (VFCs) | 4 customisable VFCs + MODBUS RTU |
| Display | Standard digital display | Larger, 3.95-inch full-colour LCD |
Understanding Pumpless Pressurisation Systems
The Mikrofill 3 PRO represents the next step in pumpless pressurisation technology. By using the available mains or boosted cold water supply pressure to fill and maintain a system, it eliminates the need for internal pumps.
What Is Pumpless Pressurisation?
Pumpless pressurisation is a method of maintaining pressure in a sealed heating or cooling system without the use of a pump. Instead, it uses incoming water pressure to automatically top up the system whenever the pressure falls below the required level.
How Does Pumpless Pressurisation Work?
The unit continuously monitors system pressure via electronic sensors. When a pressure drop is detected, a solenoid valve opens, allowing mains-pressured water to enter the system until the pre-set cold-fill pressure is reached, at which point the valve closes.
Benefits of Using Pumpless Pressurisation
- No moving parts: Reduces mechanical wear and noise compared to pumped units.
- Energy efficient: It consumes minimal power as there is no pump to run.
- Compact footprint: Smaller and lighter units make installation in tight plant rooms easier.
- Reduced maintenance: Fewer components reduce long-term service requirements.
Compared to pumped units, pumpless pressurisation systems like the Mikrofill 3 PRO offer a more reliable, energy-efficient, and compact solution for modern building services, significantly reducing complexity.
Simplify Compliance with Integrated Category 4 Protection
Water regulations require strict safeguards when connecting sealed heating systems to potable water supplies. The Mikrofill 3 PRO is the only pressurisation unit of its kind to incorporate WRAS-approved Fluid Category 4 backflow protection directly within the filling device, providing a compliant permanent filling solution without relying on separate RPZ valve arrangements.
Integrated Backflow Prevention Versus RPZ Valves
RPZ valves protect potable water supplies through a double check valve assembly with a monitored pressure zone that discharges contaminated water when backflow risk occurs. While effective, they require water authority approval, installation complexity and annual certification testing.
The integrated design of Mikrofill 3 PRO reduces reliance on separate RPZ valve installations, simplifying system layout and removing ongoing RPZ testing requirements. For consultants and contractors, this can reduce installation complexity and long-term compliance administration.
| Traditional RPZ Valve Approach | Mikrofill 3 PRO Approach |
| Separate RPZ valve required | Protection built into filling device |
| Annual RPZ testing and certification | No RPZ testing required |
| More components to install | Simplified installation |
| Higher compliance admin | Streamlined compliance |
| Increased potential failure points | Fewer potential failure points |
But don’t Category 4 systems always need an RPZ valve?
A common misconception, but no. Under the Water Supply (Water Fittings) Regulations, Fluid Category 4 systems require an approved method of backflow prevention to protect the potable water supply from contamination. RPZ valves are one recognised solution, but they are not the only option.
As Water Regs UK explains, backflow prevention can be provided by either:
A mechanical backflow prevention device, such as a Type BA or RPZ valve OR A non-mechanical arrangement, such as a Type AB air gap.
How does the Mikrofill 3 PRO Deliver Integrated Category 4 Protection?
The Mikrofill 3 PRO provides category 4 backflow protection through a controlled filling process and atmospheric separation.
The unit monitors both mains and system pressure. When system pressure drops, valves open to refill the system. Once pressure is restored, the chamber drains via a tundish and admits air, creating an atmospheric break that prevents backflow.
This combination of air-gap separation and controlled filling has been tested and approved by WRAS for Fluid Category 4 protection, confirming compliance with backflow prevention requirements.
Mikrofill 3 PRO LED Display Screen
Pressurisation Challenges in Modern Building Systems
Modern plant rooms and hydronic systems present unique challenges that traditional pressurisation units often fail to address. From strict compliance demands to the need for better data and durability, these issues can lead to increased downtime and maintenance costs if not managed correctly.
Where Traditional Pressurisation Systems Fall Short
- Compliance Risks: Failure to meet WRAS Category 4 requirements can risk contamination and regulatory issues. Systems without integrated protection require additional backflow devices.
- Servicing Access in Plant Rooms: Limited access and poorly designed units can require system shutdowns during servicing, disrupting facility operations.
- Late Leak or Fault Detection: Older systems often fail to detect leaks early. Without accurate monitoring or volume logging, systems may top up for months before a problem is discovered.
- Pressure Limitations: Older pressurisation units often have lower pressure limits, which can restrict specification flexibility for modern heating and chilled water systems.
- Limited System Visibility: Many units only provide basic fault alarms. This leaves facility teams with limited insight into system performance, making remote monitoring more difficult.
- Limited Carbon Transparency: Without verified embodied carbon data, it is difficult to assess environmental impact without time-consuming manual calculations.
- Plant Room Conditions: Dust, humidity and fluctuating temperatures can affect plant room equipment. Units with poor protection ratings may be more vulnerable to premature failure.
These real-world challenges directly shaped the engineering behind the Mikrofill 3 PRO.
Engineered for Modern Pressurisation Challenges
The Mikrofill 3 PRO has been developed to address the operational and compliance challenges engineers face when designing and maintaining modern heating and cooling systems.
Benefits of Going PRO
PRO Compliance: Integrated Category 4 Protection
Backflow compliance is a key specification requirement. Mikrofill 3 PRO integrates WRAS-approved Category 4 backflow protection directly within the filling device, providing a compliant permanent filling solution without relying on separate RPZ valves.
PRO Serviceability: Designed for Easy Maintenance
Pressurisation units can be difficult to access once installed. The Mikrofill 3 PRO is engineered for full in-situ servicing and live testing, enabling engineers to diagnose and service the unit without shutting down the system.
PRO Diagnostics: Identify Faults Earlier
Traditional systems often detect issues late. Mikrofill 3 PRO combines electronic pressure monitoring, flow measurement and Smart Fault Logic to identify abnormal make-up water usage and system faults earlier.
PRO Performance: Expanded Pressure Capability
Higher pressure capability improves system compatibility. The Mikrofill 3 PRO increases the maximum inlet pressure to 9 bar and the maximum delivery pressure to 8.7 bar, expanding its application across modern commercial systems.
PRO Connectivity: Integrated BMS Monitoring
Modern plant rooms rely on centralised monitoring. The unit includes MODBUS RTU communication and configurable BMS outputs, enabling pressurisation alarms and system data to integrate with building management systems.
PRO Reliability: Built for Real Plant Room Conditions
Plant room environments expose equipment to dust and moisture. The upgraded IP55 enclosure improves protection against ingress, supporting more reliable operation in demanding mechanical environments.
PRO Transparency: TM65 Embodied Carbon Data
Sustainability reporting is increasingly important for building services design. Mikrofill 3 PRO provides embodied carbon data calculated using the CIBSE TM65 methodology, supporting lifecycle carbon assessments.
PRO Durability: Built for Long-Term System Operation
Improved enclosure protection, modular design and service-friendly architecture support reliable long-term operation while simplifying routine maintenance and component replacement.
By combining compliance, diagnostics, serviceability and performance improvements, Mikrofill 3 PRO provides a future-ready solution for reliable pumpless pressurisation.
Specifying a New Heating and Cooling System? It’s Time to Bring in the PROs
The Mikrofill 3 PRO represents the next evolution of the market-leading pressurisation platform. With integrated Category 4 protection, smarter diagnostics and improved serviceability, it helps engineers simplify compliance, reduce downtime and improve long-term system reliability.
Learn more about the Mikrofill 3 PRO and enquire today.
Frequently Asked Questions
Pumpless pressurisation uses incoming mains pressure to maintain system pressure. Pumped pressurisation units rely on mechanical pumps, which increase energy use, noise, maintenance requirements, and overall system complexity.
Mikrofill 3 PRO uses controlled filling and atmospheric separation. When filling stops, the transfer chamber drains through a tundish and admits air, creating an atmospheric break that prevents backflow.
Yes. Mikrofill 3 PRO integrates WRAS-approved Category 4 backflow protection within the filling device, removing the need for separate RPZ valves and simplifying installation and compliance.
Through Modbus RTU and configurable outputs, Mikrofill 3 PRO can transmit system pressure status, alarms, refill activity and diagnostic alerts to building management systems.
