Keeping HVAC airways clean
18 October 2017
Richard Betts, managing director of RABScreen, an external filter specialist, discusses the importance of airflow in heating and cooling systems
Airflow is the single most critical element in the correct operation of all air heating and cooling systems. Yet many systems do not have the correct airflow.
As a result compressors overheat, fans blow hot air and heat exchangers at their heart cannot provide the capacity and comfort that their manufacturers built and designed into them.
Accurate cooling or heating analysis cannot be performed, system performance cannot be measured, and the servicing or commissioning process will be compromised if airflow is anything but correct – just ask any HVAC manufacturer.
We heat and cool air, humidify it, dehumidify it, clean it, move it, supply it, return it and try to monitor it. All of these processes are jeopardised if the designed airflow to the system is restricted.
The recent economic climate, has caused nationwide cutbacks on staffing and budgets. Fewer staff on site means a reduced capacity for maintenance and servicing. However, the objective of any maintenance team has not changed. It is very simple:
• Achieve adequate building cooling or heating.
• Minimise labour time and maximise efficiencies.
• Reduce down time breakdowns.
• Maintain customer satisfaction.
Highly qualified engineers are wasting hours on the environmentally unfriendly, chemical cleaning of coil fins instead of fine tuning and balancing the sensitive air handling systems they are trained to maintain.
Measuring, monitoring and maintaining correct airflow should be the first step when servicing equipment. It is the key component for proper equipment operation. Energy consumption is dramatically increased when compressors and fans have to work harder to maintain design output and this means big money is needlessly vanishing into thin air.
Also if an expensive compressor needs to be changed and the technician has not fully determined why it failed, the new compressor is sure to fail for the same reasons. Indeed compressors installed by service technicians fail at six to seven times the rate of original equipment.
In most regions of the UK, pollen is a major contributor to the fouling of cooling equipment. This, combined with general debris caused by foliage, refuse and other airborne particulates, can have a significant impact upon the day-to-day running of equipment.
It has always been difficult to add filtration to cooling equipment (water and dry air cooled), small condensers and cooling towers. Yet products such as the RABScreen external filtration now offer a solution to air intake debris, contaminated coils and clogged cooling tower sumps. These screens are easily fitted externally and prevent contaminates in the air entering the system. This saves money by extending the life of disposable filters, saves as much as 30% of input energy on chiller coils and saves labour by reducing cleaning and chemical use.
As a result, the typical return on investment of fitting RABScreen air intake screens is less than six months. These air intake screen are a black engineered mesh, which is heavy duty and high abrasion resistant; incoming debris held in place on the mesh is easily removed by vacuum, brush or washing during regular maintenance.
During the summer, coil cleaning, changing of internal air filters and general HVAC maintenance must be carried out more frequently, consuming much of the engineering team’s routine programmed maintenance schedule.
Similarly, the correct monitoring of airflow through cooling towers will help to minimise the risk of decaying debris such as insects, seeds and pollen forming a nutrient source for legionella bacteria.
It pays dividends to keep HVAC clean. By doing so, energy consumption is reduced considerably; it reduces the regular maintenance needed on cooling systems; and increases the efficiency of the equipment ensuring its long life.