Guide to Refurbishing Heating Systems

Refurbishing a heating system in a building is a complex task that requires careful planning, design, and execution to ensure efficient and reliable operation. Whether you are replacing old boilers, switching from district heating to standalone systems, or upgrading system controls, the following guide outlines key considerations for a successful refurbishment.

 

Perform a Full Hydraulic Survey

 

A hydraulic survey is the cornerstone of any heating system refurbishment. It ensures that the existing pipework, pumps, and components are capable of delivering heat effectively in the new system.

 

Why is this important?

• Identify System Imbalances: Existing pipework may not be hydraulically balanced, leading to uneven heat distribution or excessive strain on certain components.
• Verify Flow Rates and Pressure Losses: Ensure that the new system components (e.g., boilers, pumps, valves) are compatible with the hydraulic characteristics of the system.
• Prevent Future Issues: An unbalanced system can cause inefficiencies, increased energy costs, and inadequate heating in some zones.

 

Key Actions:

• Assess pipework condition, diameter, and layout.
• Measure pressure drops and flow rates across all zones and circuits.
• Identify potential restrictions, such as blockages or poorly sized components.

 

Provide a Detailed Specification

 

A clear and comprehensive specification ensures that the mechanical installation and BEMS (Building Energy Management System) controls are designed to meet the needs of the building.

 

Why is this important?

• Avoid Miscommunication: A detailed specification reduces misunderstandings between design, installation, and commissioning teams.
• Ensure Compatibility: Defines the requirements for equipment sizing, flow temperatures, and control strategies, ensuring seamless integration.
• Optimize Performance: Detailed control logic, valve sizing, and pump modulation strategies are critical for energy efficiency and occupant comfort.

 

Key Actions:

• Specify equipment capacities, such as boiler output, pump flow rates, and valve types.
• Define control strategies for each heating circuit, including pump sequencing, temperature control, and fault handling.
• Include detailed descriptions of operational requirements for the BEMS.

 

Evaluate the Condition of Existing Equipment

 

Retaining old equipment, such as pumps, valves, or pipework, may seem cost-effective but can cause significant issues.

 

Why retaining old equipment can cause problems:

• Reduced Efficiency: Older pumps and valves may not perform to modern standards, leading to inefficiencies and increased energy consumption.
• Wear and Tear: Worn components may fail prematurely, causing downtime and costly repairs.
• Compatibility Issues: New systems may not operate optimally with outdated components, creating flow restrictions or control mismatches.

 

Key Actions:

• Assess the condition of pumps, pipework, and valves. Replace any components that show signs of wear or reduced performance.
• Ensure compatibility between retained components and new equipment, particularly in terms of flow rates, pressure, and control signals.

 

Address Pipework and Hydraulic Design

 

Pipework is often overlooked during refurbishments but plays a critical role in system performance.

 

Common Issues:

• Blockages and Scaling: Old pipework may be clogged with sludge or scale, restricting flow.
• Inadequate Insulation: Poor insulation increases heat loss and reduces system efficiency.
• Imbalanced Distribution: Existing pipework may not support even heat distribution, especially if the system layout has been modified.

 

Key Actions:

• Flush and clean pipework to remove debris and sludge.
• Reinsulate pipework to minimize heat loss.
• Perform a hydraulic balance to ensure proper flow distribution.

 

Optimize Pumps and Valves

 

Pumps and valves are critical for distributing heat effectively throughout the system.

 

Key Considerations:

• Pump Sizing: Pumps must be sized to match the hydraulic requirements of the system. Oversized or undersized pumps can cause inefficiencies or fail to deliver adequate flow.
• Valve Functionality: Faulty or poorly sized valves can cause zones to overheat or underheat, leading to occupant discomfort.

 

Key Actions:

• Replace outdated pumps with modern, energy-efficient models.
• Specify valve types that suit the system’s control strategy.
• Implement pump run-on periods to prevent overheating and ensure residual heat distribution.

 

Upgrade and Optimize the BEMS

 

Modern BEMS controls are essential for efficient operation of heating systems, particularly in larger buildings with multiple zones.

 

Why is this important?

• Energy Efficiency: BEMS allows for dynamic control of heating, adapting to changes in demand and reducing energy consumption.
• Fault Detection: Automated alarms and fault logging can identify issues before they escalate.
• Improved Comfort: Occupant comfort is maintained by optimizing setpoints, pump speeds, and valve positions.

 

Key Actions:

• Integrate the BEMS with all heating circuits, pumps, and valves.
• Define clear control logic for temperature setpoints, pump modulation, and fault alarms.
• Include demand-based strategies, such as optimum start/stop and weather compensation.

 

Commission the System Thoroughly

 

A proper commissioning process ensures that all components operate as intended and the system performs efficiently.

 

Key Steps:

• Test and verify all hydraulic, mechanical, and control systems.
• Adjust setpoints, valve positions, and pump speeds based on actual building demand.
• Document the commissioning process and provide a comprehensive Operation and Maintenance (O&M) Manual.

 

Plan for Long-Term Maintenance

 

A well-maintained system will deliver reliable performance and energy efficiency over its lifespan.

 

Key Actions:

• Schedule regular maintenance, including filter cleaning, valve calibration, and pump inspections.
• Monitor system performance via the BEMS to identify and address issues proactively.
• Update the O&M Manual with any changes to system configuration or control strategies.

 

Conclusion

 

Heating system refurbishments require careful planning and execution to ensure success. Start with a full hydraulic survey to understand the current system and inform the design of the new installation. Provide a detailed specification that addresses both mechanical and control requirements, and replace outdated equipment to avoid inefficiencies and failures.
 

Finally, focus on commissioning and ongoing maintenance to optimize system performance and extend its lifespan. By following these steps, you can deliver a heating system that meets the needs of the building while minimizing energy consumption and operational costs.