The key to lower building costs and fresher air is a clean air conditioning system, says Barry Lea, who offers FMs essential advice on A/C maintenance.
2 October 2015 | By Barry Lea
Does your building surround people with fresh, beautifully clean, air-conditioned luxury? Or does it subject them to odd smells, allergies and air-conditioning misery?
Good air conditioning hygiene increases a building's energy efficiency, lowers its carbon footprint, improves indoor air quality and saves the FM's time, energy and money.
If the coils of your air conditioning system are dirty, the results will include unpleasant odours, allergic reactions and the spread of diseases. In short, poor Indoor Air Quality (IAQ).
All of these avoidable symptoms stem from the microbes that gather and breed in dirt collecting on the air conditioning coils and in their associated condensate trays.
Take away the dirt and these objectionable organisms will have nowhere to live. By keeping your air conditioning coils clean you will increase the energy efficiency, effectiveness and service life of the air conditioning system, which means major cost savings.
The dirt coating any air conditioning coil's surfaces acts as an insulating blanket, seriously affecting its ability to function effectively.
To achieve the same cooling effect, your system has to work harder, using more energy and putting extra pressure on its components - particularly the compressor, an expensive item to replace.
If the compressor were to fail, it could lead to water leakage and damage to the fabric of your building. Dirty air conditioning coils can cause:
- Increased energy consumption;
- Increased operating pressures and temperatures;
- Reduced heat transfer within the system;
- Decreased capacity to cool;
- Increased wear on the system, which can lead to component damage, system malfunctions and reduced life expectancy;
- Reduced building energy efficiency; and
- Poor indoor air quality and potential for contamination (evaporators only).
This summary of the functioning of the coils should help to explain how dirt affects both system efficiency and the quality of the air breathed by workers.
A typical air conditioning system has an indoor cooling coil (evaporator) and an outdoor condensing coil (condenser).
The building's air is constantly circulated through the evaporator coil. Dirt in the air will attract and stick to the evaporator's cooling surfaces as it passes over them. To minimise this, and to help prevent the recirculation of airborne dirt, a filter is often fitted.
Unfortunately, filters are rarely 100 per cent efficient - particularly when it comes to stopping very small items such as dust and microbes. Dirt on the evaporator coil, and in the moist environment of its associated condensate tray, is the main habitat in the system for microbes.
The job of an air conditioning condenser is to dissipate heat absorbed from the refrigerant. The condenser coil may be air-cooled or water-cooled and will accumulate dirt just as an evaporator coil does. If the condenser is indoors - in a large warehouse, for example - it can harbour microbes that affect IAQ.
Changes to the Indoor Air Quality (IAQ) are the first things to be noticed by building occupants. The main culprits involved are fungi, bacteria and viruses. As we all know, bacterial activity often causes nasty smells. Fungi produce spores and defensive toxins, which can trigger allergic reactions.
The bacteria and viruses include a number of organisms that cause disease in humans through airborne infection.
All of these contaminants are constantly being pumped into the air by dirty systems. To avoid the costly and unhygienic problems described above, coil cleaning needs to become part of a planned regime of regular maintenance. Advanced Engineering recommends a three-stage treatment process:
1. Clean and disinfect the coil and condensate tray. Use a good quality combined cleaner and disinfectant - one that meets the appropriate British and European Standards for both bactericide and fungicide. Heavy-duty disinfectants or one of the new breed of foaming cleaners will work best for a particularly dirty or rarely serviced system.
2. Apply a protective coating to the coil and condensate tray. This is an excellent tip to keep microbes at bay. The coating is not rinsed off; it remains in place (depending on the environment) for a minimum of six to 12 months, acting like a non-stick layer, preventing dirt and microbes from sticking to the treated surfaces.
3. Place a disinfectant strip in the condensate tray. These are readily available and will slowly leach out a disinfectant, killing any microbes washed into the tray and preventing any further micro-organic growth. This helps to control bacteria and odours, and the strips and condensate mixture will also clean and disinfect the drain lines as they wash away. As a finishing touch, a fragrance-enhancing gel can be added to the unit to give a 'just-cleaned' freshness.
Barry Lea is chairman of Advanced Engineering