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Heating & Hot Water Maintenance

Air Source Heat Pump (ASHP) Maintenance Checklist

Keep your air source heat pump delivering efficient low-carbon heat — coil and fan checks, refrigerant and F-Gas compliance, defrost operation, and flow-temperature verification.

What is an air source heat pump maintenance checklist?

A air source heat pump (ashp) maintenance checklist is a structured list of the 11 preventive maintenance tasks — covering visual, functional, cleaning, safety and record-keeping checks — that keep an air source heat pump (ashp) running safely and reliably. It groups routine checks by frequency, from daily inspections to annual servicing, so FM teams and building engineers can plan and evidence preventive maintenance.

Core air source heat pump checks

  • Inspect the plate heat exchanger / condenser and system water quality
  • Check the fan and motor for operation, balance, and bearing noise
  • Inspect and clean the evaporator coil and outdoor unit of debris, leaves, and dust
  • Carry out F-Gas leak checks as required by the refrigerant charge
  • Record COP/performance, refrigerant data, and F-Gas checks in the log

What is an air source heat pump (ashp)?

An air source heat pump (ASHP) extracts low-grade heat from outside air and upgrades it to useful heating and hot water using a refrigerant circuit and compressor. Increasingly central to building decarbonisation and Part L compliance, ASHPs run year-round and depend on clean coils, a healthy refrigerant charge, correct flow temperatures, and reliable defrost operation for their efficiency (measured as coefficient of performance, COP). Because they contain fluorinated refrigerant, they fall under the F-Gas Regulations, requiring leak checks and record-keeping. Maintenance protects both efficiency and compliance.

Typical Air Source Heat Pump maintenance checklist

A practical starting point for planned preventive maintenance. Always refer to the manufacturer's O&M manual and site-specific requirements.

Visual Checks

  • Inspect the plate heat exchanger / condenser and system water quality
  • Check condensate drainage from the outdoor unit is clear and frost-protected

Functional Checks

  • Check the fan and motor for operation, balance, and bearing noise
  • Verify refrigerant circuit performance — pressures, superheat, and subcooling
  • Confirm the defrost cycle initiates and clears ice correctly
  • Check flow and return water temperatures against the design (lower is more efficient)
  • Verify controls, weather compensation, and setpoints are optimised
  • Confirm the electrical supply, isolation, and any soft-start operate correctly

Cleaning & Housekeeping

  • Inspect and clean the evaporator coil and outdoor unit of debris, leaves, and dust

Safety Checks

  • Carry out F-Gas leak checks as required by the refrigerant charge

Record Keeping

  • Record COP/performance, refrigerant data, and F-Gas checks in the log

Typical maintenance frequency

Suggested intervals for air source heat pump (ashp) maintenance. Actual frequencies should follow manufacturer guidance and site-specific risk assessments.

Quarterly

  • Clean outdoor coil and check fan
  • Verify flow temperatures
  • Check defrost and condensate

Annually

  • Full service and F-Gas leak check
  • Refrigerant performance check
  • Water quality and heat exchanger inspection
  • Controls optimisation

Common faults and issues

Issues to be aware of when maintaining air source heat pump (ashp) equipment.

Fouled or iced evaporator coil reducing efficiency and capacity
Refrigerant leak lowering COP and breaching F-Gas record-keeping duties
Defrost cycle faults leaving ice build-up that blocks airflow
Flow temperatures set too high, collapsing efficiency
Blocked or frozen condensate drain on the outdoor unit
Poor system water quality fouling the plate heat exchanger

Safety and compliance notes

Key safety considerations for air source heat pump (ashp) maintenance. This is general guidance only — always follow OEM instructions, statutory requirements, and your organisation's safe systems of work.

Only F-Gas certified engineers should work on the refrigerant circuit
F-Gas leak checks and records are a legal requirement based on refrigerant charge
Isolate electrically before access — heat pumps carry significant electrical loads
Keep the outdoor unit clear of obstructions for proper airflow
Manage condensate to prevent ice hazards in cold weather
How PM Assist helps

Managing Air Source Heat Pump documentation with PM Assist

PM Assist helps FM and building operations teams search their O&M manuals and building drawings in seconds. Upload your air source heat pump (ashp) documentation and ask questions like “What flow temperature is the ASHP set to?” or “What refrigerant and charge does it hold?” — and get source-cited answers instantly.

See PM Assist answer questions about a real air source heat pump manual — try the live demo, no signup needed.

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PM Assist gives FM teams instant access to O&M manuals, drawings, and maintenance knowledge — all searchable with AI.

  • Upload and organise building documentation
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  • Source-cited answers for maintenance queries
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