What is the difference between a heat pump's refrigerant circuit and non-refrigerant circuit?

The refrigerant circuit is a sealed loop containing refrigerant that absorbs and releases heat via the evaporator and condenser. The non-refrigerant circuit includes the water or air systems that distribute the heat to the building. In an air-to-water heat pump, the non-refrigerant circuit consists of pipework, radiators or underfloor heating, a buffer vessel, and controls. The refrigerant circuit is handled by a qualified F-Gas engineer, while the non-refrigerant circuit is the focus of this award.

Do I need to be F-Gas certified to install heat pumps?

No, for this qualification you do not need F-Gas certification because it covers only the non-refrigerant circuits. However, if you want to work on the refrigerant side (e.g., connecting or repairing the sealed system), you would need an F-Gas Category 1 certificate. Many installers work alongside a refrigeration engineer for that part.

Why do heat pumps need buffer vessels?

Buffer vessels increase the water volume in the system, which helps prevent the heat pump from short cycling (turning on and off too frequently). They also provide thermal mass to store heat during defrost cycles and help maintain stable flow temperatures. Sizing the buffer vessel correctly is crucial for system efficiency and longevity.

Can I install a heat pump with my existing radiators?

It depends on the heat loss of your property and the size of your radiators. Heat pumps operate at lower flow temperatures (typically 35-45°C), so radiators designed for higher temperatures (e.g., 70°C) may not provide enough heat output. A heat loss calculation will determine if your radiators are adequate or if you need to upsize them or switch to underfloor heating.

What maintenance does a heat pump system require?

Regular maintenance includes checking and cleaning air filters (for air source heat pumps), inspecting the outdoor unit for debris, checking system pressure and expansion vessel charge, testing controls and weather compensation, and taking water samples to ensure inhibitor levels are correct. Annual servicing by a qualified engineer is recommended to maintain efficiency and warranty.

How do I size pipework for a heat pump system?

Pipework sizing is based on the flow rate required to deliver the heat output, which depends on the heat pump's capacity and the design temperature drop (usually 5-10°C). Use the formula: flow rate (L/s) = heat output (kW) / (4.18 × ΔT). Then select pipe diameter to keep velocity below 1.5 m/s to avoid noise and erosion. Refer to manufacturer guidelines and standard pipe sizing charts.

Know the requirements to install, commission and handover heat pump systems _non-refrigerant circuits_

EAL

vocational

This subtopic covers the essential knowledge required for the non-refrigerant aspects of heat pump system installation, including health and safety legislation, system design principles, component identification, installation preparation, testing, commissioning, and handover. Learners must understand how to apply relevant regulations and standards to ensure safe and effective integration of heat pump units with hydraulic emitter circuits in both air and ground source configurations.

Learning Outcomes

Assessment Guidance

Key Skills

Key Terms

Assessment Criteria

Assessment criteria

EAL Level 3 Award In the Installation and Maintenance of Heat Pumps Systems (Non-refrigerant Circuits)

Topic Overview

The EAL Level 3 Award in the Installation and Maintenance of Heat Pump Systems (Non-refrigerant Circuits) is a specialist qualification for experienced heating and plumbing professionals. It focuses on the non-refrigerant side of heat pump systems, covering the design, installation, commissioning, and maintenance of the water and air circuits that distribute heat. This includes pipework, radiators, underfloor heating, buffer vessels, and controls, but excludes the refrigerant circuit itself. The qualification is essential for those looking to expand their skills into low-carbon heating technologies, as heat pumps are a key part of the UK's strategy to reduce carbon emissions from buildings.

This award is particularly relevant for gas engineers, plumbers, and heating installers who want to work with air source and ground source heat pumps. It covers the principles of heat pump operation, system design considerations (such as flow temperatures and emitter sizing), and the practical skills needed to install and maintain the non-refrigerant components. Students will learn how to size pipework, select appropriate heat emitters, and commission controls to ensure efficient operation. The qualification also emphasizes safety, including electrical isolation and proper handling of system water to prevent corrosion and microbial growth.

In the wider context of construction and building services, this qualification supports the transition to net-zero carbon heating. Heat pumps are increasingly mandated in new builds and retrofits, making this skill set highly sought after. By mastering the non-refrigerant circuits, students can confidently offer heat pump installation services, ensuring systems operate at optimal efficiency and meet building regulations. This award is a stepping stone to further qualifications in heat pump technology and renewable energy systems.

Key Concepts

Core ideas you must understand for this topic

→Heat pump system components: Understand the function of the evaporator, condenser, compressor, and expansion valve in the refrigerant circuit, and how they interact with the non-refrigerant circuits (e.g., the water circuit that carries heat to the building).
→Flow temperature and emitter sizing: Heat pumps operate most efficiently at lower flow temperatures (35-45°C) compared to boilers. This means radiators must be oversized or underfloor heating used to deliver the same heat output. Students must calculate heat loss and select emitters accordingly.
→Buffer vessels and thermal stores: These are used to prevent short cycling of the heat pump and to manage defrost cycles. Understanding their sizing and connection is critical for system stability.
→System water treatment: Proper cleaning, flushing, and inhibition of the water circuit are essential to prevent sludge, corrosion, and bacterial growth (e.g., Legionella). This includes using appropriate chemicals and filters.
→Controls and weather compensation: Heat pump controls must modulate output based on outdoor temperature and indoor demand. Students need to know how to set up weather compensation curves and zone controls for maximum efficiency.

Learning Objectives

What you need to know and understand

Know the health and safety risks and safe systems of work associated with heat pump system installation work (non-refrigerant circuits), Know the requirements of relevant regulations/standards relating to practical installation, testing and commissioning activities for heat pump installation work, Know the purpose and operational characteristics of heat pump unit and heat pump system components, Know the different types of heat pump units and system arrangements for hydraulic emitter circuits, Know the fundamental principles of heat pump selection and system design that are common to both air and ground source heat pumps, Know the fundamental design principles for ground source ‘closed loop’ heat pump collector circuit design, component sizing and installation, Know the layouts of ‘open loop’ water filled heat pump collector circuits, Know the fundamental design considerations and principles that are specific to air source heat pumps, Know the preparatory work required for heat pump installation work, Know the requirements to install and test heat pump systems (non-refrigerant circuits), Understand the requirements to commission heat pump system installations (non-refrigerant circuits), Understand the requirements to handover heat pump system installations

Assessment Criteria

Key criteria assessors look for in your portfolio

Award credit for demonstrating a thorough risk assessment process specific to heat pump installation, referencing COSHH, manual handling, and electrical safety for ancillary circuits.
Expect clear identification and explanation of key heat pump components (e.g., circulation pumps, expansion vessels, buffer tanks, low-loss headers) and their roles in system operation.
Credit for accurate comparison of ground source collector types (closed-loop horizontal, vertical borehole, open-loop) and their design implications.
Award marks for detailed commissioning procedure steps, including system flushing, filling, pressure testing, and setting flow rates according to manufacturer instructions.
Look for comprehensive handover documentation that includes user operating instructions, maintenance schedules, and performance benchmark data.

Assessment Guidance

Guidance for achieving higher grades

💡Always relate your answers to the specific 'non-refrigerant' scope: focus on water pipework, controls, electrics (up to the isolator), and mechanical installation.
💡Structure your evidence to show a logical flow from preparation to handover, using manufacturer's manuals and industry standards as constant references.
💡For design scenarios, explicitly state assumptions about heat loss calculations and emitter sizing to justify heat pump selection.
💡In practical assessments, clearly verbalise your safety checks (e.g., dead testing, pressure relief valve orientation) before proceeding.
💡When answering questions on system design, always show your working for heat loss calculations and emitter sizing. Marks are awarded for method, not just the final answer. Use the correct formula (e.g., Q = U × A × ΔT) and state units clearly.
💡For commissioning questions, remember to mention the importance of recording flow and return temperatures, pressure drops, and flow rates. Examiners look for evidence that you understand the need to verify system performance against design specifications.
💡In maintenance scenarios, focus on the non-refrigerant components: checking expansion vessels, pressure gauges, and automatic air vents. Also, describe the procedure for taking water samples and interpreting results (e.g., pH, inhibitor levels). This shows practical knowledge.

Common Mistakes

Common errors to avoid in your coursework

Confusing the roles of refrigerant and non-refrigerant circuits, leading to incorrect safety procedures or overlooking water-side requirements.
Neglecting to consider anti-freeze concentration and freeze protection measures in ground source collector circuits, resulting in design flaws.
Applying air source heat pump (ASHP) siting principles without accounting for local noise regulations, planning permissions, or defrost water drainage.
Assuming all heat emitters are compatible without verifying required flow temperatures or performing hydraulic separation calculations.
Overlooking the importance of electrical isolation before working on wiring centres or controls during installation or maintenance.
Misconception: Heat pumps work like boilers and can be installed with existing radiators without modification. Correction: Heat pumps require lower flow temperatures, so existing radiators are often too small. A heat loss calculation must be done to determine if radiators need upsizing or if underfloor heating is needed.
Misconception: The refrigerant circuit is the most important part, so non-refrigerant circuits are simple. Correction: The non-refrigerant circuit is equally critical. Poor design (e.g., undersized pipework, incorrect buffer vessel sizing) can cause inefficiency, short cycling, or system failure. Proper commissioning and water treatment are also vital.
Misconception: Heat pumps don't need maintenance. Correction: Like any heating system, heat pumps require regular maintenance, including checking filters, cleaning heat exchangers, inspecting pipework for leaks, and testing controls. Neglect can lead to reduced efficiency and breakdowns.

Frequently Asked Questions

Common questions students ask about this topic

Before You Start

Prior knowledge that will help with this topic

•A good understanding of basic heating system components (boilers, radiators, pipework, pumps) and plumbing principles.
•Knowledge of heat loss calculations and building regulations (Part L of the Building Regulations) is beneficial.
•Familiarity with electrical principles (e.g., wiring controls, isolation) is helpful, as heat pump systems involve electrical connections.

Key Terminology

Essential terms to know

Know the health and safety risks and safe systems of work associated with heat pump system installation work (non-refrigerant circuits), Know the requirements of relevant regulations/standards relating to practical installation, testing and commissioning activities for heat pump installation work, Know the purpose and operational characteristics of heat pump unit and heat pump system components, Know the different types of heat pump units and system arrangements for hydraulic emitter circuits, Know the fundamental principles of heat pump selection and system design that are common to both air and ground source heat pumps, Know the fundamental design principles for ground source ‘closed loop’ heat pump collector circuit design, component sizing and installation, Know the layouts of ‘open loop’ water filled heat pump collector circuits, Know the fundamental design considerations and principles that are specific to air source heat pumps, Know the preparatory work required for heat pump installation work, Know the requirements to install and test heat pump systems (non-refrigerant circuits), Understand the requirements to commission heat pump system installations (non-refrigerant circuits), Understand the requirements to handover heat pump system installations

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Know the requirements to install, commission and handover heat pump systems _non-refrigerant circuits_

Assessment criteria

Topic Overview

Key Concepts

Learning Objectives

Assessment Criteria

Assessment Guidance

Common Mistakes

Frequently Asked Questions

Before You Start

Key Terminology

Ready to learn?

Related Topics in EAL vocational Construction & Building Services

Core Plumbing Systems

Design and Installation Practices and Procedures

Electrical Scientific Principles

Electrical Work and the Control of Plumbing and Domestic Central Heating Systems

Topic Synopsis

Key Concepts & Core Principles

Exam Tips & Revision Strategies

Common Misconceptions & Mistakes to Avoid

Examiner Marking Points

Know the requirements to install, commission and handover heat pump systems _non-refrigerant circuits_

Assessment criteria

Topic Overview

Key Concepts

Learning Objectives

Assessment Criteria

Assessment Guidance

Common Mistakes

Frequently Asked Questions

What is the difference between a heat pump's refrigerant circuit and non-refrigerant circuit?

Do I need to be F-Gas certified to install heat pumps?

Why do heat pumps need buffer vessels?

Can I install a heat pump with my existing radiators?

What maintenance does a heat pump system require?

How do I size pipework for a heat pump system?

Before You Start

Key Terminology

Ready to learn?

Related Topics in EAL vocational Construction & Building Services

Core Plumbing Systems

Design and Installation Practices and Procedures

Electrical Scientific Principles

Electrical Work and the Control of Plumbing and Domestic Central Heating Systems