Heating, Ventilating and Air Conditioning (HVAC) : Operations and maintenance

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Efficient procedures of operation and maintenance are necessary to ensure the efficient working of HVAC equipment and the provision of a healthy environment for the occupants. Causes of improper operation and unsatisfactory maintenance are generally due to lack of funds and inadequate training of the technical staff. Proper operation and maintenance will ensure reduced utility cost and assist in prolonging the life span of the equipment. Therefore, formulation of strategies regarding operation and maintenance to achieve these objectives is essential.

Operational Strategies

These strategies are prepared considering the size and number of buildings, the equipment installed, and the amount of funds that can be dedicated for the maintenance of HVAC equipment. A contract may be awarded to companies for these tasks, or ,alternatively, the same may be undertaken by technicians hired for these purposes.

Contract Services: When companies intend to concentrate on their main business, then utilization of contract services for the maintenance of HVAC equipment may be more beneficial. A contract based on time consumed and parts fitted is usually implemented. The contractor should prepare a comprehensive maintenance schedule including inspection before the heating and cooling season, change of filters, and other technical aspects. He should also provide technical reports on the state of equipment, and arrange the training of technicians.

In-House Maintenance: This may be economical and beneficial for the companies with large buildings where a’ few technicians may be employed for the maintenance of HVAC equipment. These technicians are responsible for scheduled maintenance, trouble shooting, and normal repairs, while major repairs are undertaken by firms. Staff detailed for the in-house maintenance will be more responsible, accountable, and familiar with the building plan.

Maintenance Strategies

Executing a scheduled maintenance plan to keep the equipment in an operational condition can cause a reduction in energy costs by 5% to 15% and also increase the life span of the equipment. Though the maintenance plan will require some initial investment, the financial advantages obtained over a period of time will compensate for the funds allocated for this purpose. The fundamental maintenance tasks could be easily done by the technicians trained on handling the HVAC equipment. The characteristic of a good maintenance plan is that it will diagnose and rectify a problem in its initial stages, by a little expenditure, and will thus prevent the occurrence of major troubles that require enormous expenditures. Down time due to breakdowns will also be reduced.

Maintenance Plan

An efficient maintenance plan should include:

  • A program for periodic maintenance that should be performed in accordance with the manufacturer’s instructions, including details of all inspections that will be carried out.
  • A determination of the budget required for maintenance.
  • Establishing the availability of recommended parts.
  • Establishing proper documents for the maintenance system, including work orders, cost of each part, etc.
  • A training program for the technicians concerning maintenance.
  • The availability of operator manuals for all the HVAC equipment

HVAC Maintenance Guidelines

It is recommended that maintenance of HVAC equipment be carried out as follows:

Filters: The function of filters is to maintain the quality of indoor air and ensure protection of the components from dirt that affects their performance efficiency. The filters enclosed in cardboard with holes should be avoided since these decrease their operative area, and increase the drop in pressure. Performance of the pleated fiber filters is better since filtration efficiency is enhanced by fabric, the effective area is increased by pleats, the pressure drop is reduced, and the life of filters is increased. Filters should be changed based on pressure drop across the filter, visual inspection, or calendar scheduling.

Evaporator and Condenser Coils: Dirt on evaporator coils reduces air flow in the system. The heat transfer efficiency of coils is reduced by dirt, thereby decreasing the cooling capacity. The evaporator coil will remain clean by good filtration, and should therefore be inspected at minimum on a yearly basis to confirm the usefulness of the filters. The exposure of condenser coil to unfiltered outside air makes it more vulnerable to degradation by dirt, and should therefore be cleaned periodically.

Compressor: In an overcharged system, surplus refrigerant stores in the condenser, and makes the compressor work harder. In an undercharged system, refrigerant is reduced in the evaporator and cooling capacity is decreased. This is indicated by frosting on the entrance of evaporator and a warm suction line. Undercharging occurs due to some leakage in the system. A compressor that is not producing the desired cooling effect may require replacement when the discharge pressure is reduced, or the suction pressure is increased, beyond the limits recommended by the manufacturer.

Fan, Bearings and Belts: Impellor blades can be filled with dirt that can be minimized by good filtration. Indications of bearing malfunction are unnecessary sound, excessive vibration, or heated bearings. Fans should be oiled in accordance with the recommendations of the manufacturer. Suitable tension should be maintained in the belts, and application of grease should be proper.