Maintaining Air Source Heat Pumps for Low-Temperature Hot Water (LTHW) Heating Systems

Air Source Heat Pumps (ASHPs) are becoming more popular across the globe and appearing in more projects across all regions, most probably as a result of the push to move away from traditional gas-fired boilers / heating systems. The systems work by exchanging energy from outdoor air, via the refrigeration cycle, to HHW / LTHW serving a building’s heating system such as to FCU’s, AHU’s or LTHW radiators and / or the building domestic hot water system. To operate effectively and efficiently, regular maintenance is essential. We have reviewed the key maintenance requirements of the system components below.

Regular Inspection and Cleaning

Outdoor Unit: The outdoor unit ASHP is exposed to environmental conditions and can accumulate dirt, leaves, and other debris that affect performance.

• Cleaning Coils: Clean the condenser and evaporator coils periodically to remove dirt and debris. Use a soft brush or a vacuum to gently clean the coils. Avoid using water directly on the coils to prevent damage.
• Clearing Debris: Regularly clear any debris such as leaves or branches from around the outdoor unit. Ensure there is at least 1-2 feet of clearance around the unit for proper airflow.

Leaks and Corrosion: Inspect the heat exchanger for any leaks or signs of corrosion. Address any issues promptly to avoid reduced efficiency or damage.

Inspecting and Maintaining Heat Pump Components

Refrigerant Levels: The refrigerant in an ASHP is crucial for transferring heat. Low refrigerant levels can indicate leaks or other issues.

• Inspection: Have a professional technician check the refrigerant levels regularly. If levels are low, a technician can identify and repair leaks and recharge the system as needed.

Electrical Components: Inspect the electrical components for any signs of wear or issues.

• Wiring Check: Ensure all wiring and connections are secure and free of corrosion. Look for any signs of fraying or damage.
• Connections: Verify that all electrical connections are tight and secure.

Seasonal Preparations

Winter Preparation: In colder climates, ensure the ASHP is prepared for winter conditions.

• Insulation: Insulate any exposed pipes and ensure the outdoor unit is protected against freezing temperatures.
• Defrosting: Check the defrosting cycle of the outdoor unit to ensure it operates correctly in freezing conditions.

Summer Preparation: During warmer months, make sure the system is ready for increased cooling demands. If the ASHP has a cooling function, ensure it is functioning correctly and efficiently.

All of Dewick & Associates O&M manuals provide step-by-step Preventative Maintenance Log sheets for all plant and equipment within the project installation which are used on site throughout the life of the building.

Author: Louise Gardner, General Manager of Dewick & Associates