Prevention is better than cure, or in industrial maintenance terms, condition monitoring is more effective than failure maintenance. RAB Specialist Engineers has over 30 years' experience in the air-handling industry, and Richard Betts offers some practical advice on how to maintain costly HVAC equipment while reducing expensive maintenance schedules, simply by fitting air intake filter screens
Businesses are wasting thousands of pounds each year due to inefficient air-handling systems that require replacement or frequent maintenance. This can have significant cost implications for any business's profitability.

For every 1,000 ton of refrigeration capacity, consuming 750kW of compressor energy, an additional £31.50 an hour or £63,000 a year is incurred from inefficient systems based upon 2,000 hours service.

Well-maintained equipment costs less to operate, ensures optimal life expectancy and maximises energy efficiencies. Furthermore, ensuring that your HVAC equipment delivers consistent high-level performance alleviates the need for unnecessary servicing and warranty claims.

Energy increase
Restricted airflow through HVAC equipment will occur when components such as condenser and evaporator coils, become clogged up with debris. To compensate for this reduction of airflow, compressor motors are required to work harder and can use more energy. In fact, a study carried out by Pacific Gas & Electric, one of the largest US-based gas and electric utility companies, suggests that compressor energy consumption can increase by up to 30% if condenser coils become soiled.

In his book, Troubleshooting and Servicing Modern Air Conditioning and Refrigeration Systems, Professor John Tomczyk, from Michigan's Ferris State University, states: 'When the coil becomes fouled with dirt and grime, it cannot provide complete or adequate heat transfer, a process that was predicated on a clean coil. The equipment's compressor senses this, and tries to overcome it by going to a higher system pressure. This consumes greater levels of electricity.'

Higher operating pressures and temperatures will occur if air-handling equipment is required to use more energy and operate for longer cycle times in order to maintain normal operating levels. In this situation internal lubricants may also break down, shortening the life expectancy of the compressor motor and other HVAC components.

Air intake filter screens
In severe cases of airflow restriction a number of problems may arise including internal icing, external compressor failure and total loss of a system's cooling capacity.

Compressor replacement is the most expensive repair on any HVAC system and therefore preventative measures should be taken to avoid this. Fitting external air intake filter screens to existing and new HVAC systems will help prevent expensive repairs. Air intake filter screens work by protecting existing pre-filtration devices, and also those areas where traditional filters are not practical, such as chillers or cooling tower fill ponds, from various types of airborne debris.

By creating a static charge that attracts and traps airborne particulates, the air intake screens prevent sensitive components such as evaporators and cooling and condenser coils from contamination, without restricting airflow through the equipment.

Supplied by RAB Specialist Engineering, PreVent air intake screens have been used extensively throughout the US for more than nine years by customers including Starbucks, Harvard Law School and Motorola. Manufactured by US firm Permatron, the filters are designed to catch airborne debris before it can enter a HVAC system.

The screens are available in two formats - a three-dimensional tight weave polypropylene media, designed to catch smaller particles such as insects, pollen and construction dust or a PVC-coated polyester high abrasion media for larger debris such as leaves, paper and plastic shopping bags. Customised to fit any shape or size of HVAC system the PreVent screens come with a five-year warranty and are available with several different fixing methods including Velcro, magnetic framework and self-tapping screws.

Cost savings
With reduced maintenance schedules and repair costs, RAB Specialist Engineers estimates that the filter screens will pay for themselves in less than two years.

Inefficient HVAC systems will increase the cost of heating or cooling a building.

Fitting air intake filter screens is an effective way to help prolong the life of new and existing HVAC equipment and deliver significant long-term cost savings. With over 50 years' experience in providing custom air filter products, Permatron is now supplying the UK market through RAB Specialist Engineers.

// The author is managing director of RAB Specialist Engineers //