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Key points for maintenance of the HVAC system
2026/1/16
Maintenance of the water system: Prevent blockages, corrosion, and leakage. (Pipes, pumps, heat exchangers, cooling towers) are the "blood vessels" of the HVAC system. They are prone to blockages or equipment damage due to scale, impurities, and corrosion. The key points for maintenance are as follows:
Daily maintenance (daily): Check the running sound of the pump (no abnormal noise or vibration), and check if the pressure gauge / thermometer readings are normal; Check if there is any leakage in the pipes, valves, and interfaces (focus on weld seams and valve packing areas), and replace the seals in time if dripping or leaking is found.
Monthly maintenance: Remove the sludge and impurities in the cooling tower / expansion water tank (to prevent them from entering the pipes and blocking the heat exchanger); Check if the system补水 device (such as automatic补水 valve) is normal and ensure stable system pressure (to avoid pump idling due to water shortage).
Quarterly Maintenance: Test water quality (pH value, hardness, turbidity). The pH value of the air conditioning water should be controlled within 7.5-8.5, and the pH value of the heating water should be 8.5-10.0. If the hardness of the water exceeds the standard (more than 300mg/L), a scale inhibitor needs to be added; if the corrosion is severe (iron content more than 0.5mg/L), a corrosion inhibitor needs to be added.
Annual Maintenance: Thoroughly clean the heat exchangers (such as cleaning the tubes of shell-and-tube heat exchangers or the plates of plate heat exchangers), removing scale and impurities (scale can reduce heat transfer efficiency by more than 30%); Remove rust and apply paint to the pipes and valves (especially for outdoor pipes to prevent leakage due to rust); Replace the aging pump seals and bearings (if the running noise increases, it might be due to bearing wear).
Wind system maintenance: Prevent blockage, prevent pollution, maintain air volume. The wind system (ducts, filters, fans, air outlets) directly affects air quality and the efficiency of air supply. It is prone to filter blockage and duct pollution due to dust accumulation. The maintenance points are as follows:
Daily maintenance (weekly): Check if the fresh air inlet filter is clogged (visualize the accumulation of dust). Residential fresh air filters should be replaced every 1-2 months, while commercial fresh air filters (such as in shopping malls) should be replaced every 2-4 weeks; Clean the indoor air vents (such as air conditioning outlets, fresh air supply vents), to prevent dust accumulation and the growth of bacteria.
Monthly maintenance: Check the operation status of the fan (no abnormal vibration or noise), measure if the current of the fan is within the rated range; Check if the connection parts of the duct are leaking (you can use a smoke test: release smoke inside the duct, if there is smoke overflowing outside, it indicates a leakage point), seal the leakage points with sealant or aluminum foil tape (a leakage rate of more than 10% will result in a loss of more than 20% of air volume).
Quarterly maintenance: Clean the fan impeller (accumulated dust can cause imbalance of the impeller and increase energy consumption); Perform local cleaning of the ducts of commercial systems (the focus is on the return air ducts to prevent the accumulation of dust and mold, which could lead to indoor air pollution).
Annual Maintenance: Thoroughly clean the ducts (especially in crowded places such as hospitals and shopping malls, it is recommended to have professional institutions perform mechanical cleaning and disinfection); Check the lubrication condition of the fan bearings, add or replace the lubricating oil (if the bearing temperature is > 60℃, it may be due to insufficient lubrication).
Terminal equipment maintenance: Directly affects user experience. Terminal equipment (fan coil units, radiators, floor heating manifold) is the final step in "conveying heat and cold to the interior". Improper maintenance can lead to "large temperature differences felt by the body and high energy consumption":
Fan coil unit (air conditioning terminal):
Monthly: Clean the return air filter (dust blockage can lead to reduced air volume and poor cooling/heating performance);
Quarter: Clean the fins of the coil (use compressed air to blow off dust, or spray with a neutral cleaning agent to avoid corrosion of the fins);
Annual Inspection: Check if the condensate pan is filled with water (accumulated water can breed mold, so clean the dirt inside the pan and check if the drainage outlet is blocked).
Radiators / Floor heating:
Monthly (Heating Season): Check if the interface of the radiator is leaking and whether the valves of the floor heating manifold are functioning properly.
Annual (after the heating season): The floor heating system needs to undergo "full water maintenance" (to prevent pipe oxidation and corrosion), and the radiator surfaces need to be cleaned of dust; every 2-3 years: The floor heating system needs to have its pipes cleaned (to remove scale and impurities, especially for systems using tap water, where scale can reduce heat transfer efficiency by 20%-30%).
Host equipment maintenance: The "heart" of the system. The operation of the host (central air conditioning unit, wall-mounted boiler, heat pump unit) is the core energy-consuming equipment of the HVAC system. Maintenance of these devices needs to be carried out by professionals:
Central air conditioning unit (such as screw unit, centrifugal unit):
Quarterly: Check the refrigerant level and pressure (if insufficient, check for leaks and replenish; do not blindly add refrigerant).
Annual: Clean the condenser and evaporator (scale buildup can reduce heat transfer efficiency; use chemical descaling agents for cleaning); Check if the electrical system (terminal blocks, contactors) is loose or aged, and measure insulation resistance (to prevent short circuits).
Wall-mounted heater (gas heating):
Quarter (Heating Season): Remove carbon deposits from the burners (carbon deposits can lead to incomplete combustion, increased energy consumption, and higher exhaust gas temperature);
Annual Inspection: Check if the heat exchanger is caked (can be cleaned with citric acid); Check if the gas valve and safety valve are functioning properly (to prevent gas leakage or abnormal pressure).
Heat pump units (air source / ground source heat pumps):
Quarter: Clean the air-side heat exchanger (air-source heat pump) (to prevent dust and fluff from blocking the fins);
Annual Inspection: Check the operating status of the compressor (current, temperature). For ground source heat pumps, check if the underground pipes are leaking (pressure testing can be used).
