Treat Your AC Well – It's Worth It

It is a common misconception from most every end user, that air-conditioning equipment is a fit and forget utility. Not so, writes Phil Gillatt, Technical Director, Silentair.

It is an imperative, that at the design and pre-sales position, certain aspects of the air quality need consideration and these can be grouped into the following headings:

• Bacterial

• Humidity

• Air Quality

BACTERIAL
Dependant on the application of the indoor unit and how it is to be deployed, general staff or particular employees need to be aware that the air supply can affect them, with regards to bacterial infections. Such affects can be classified as external or internal. An employee with a heavy cold or other air-borne illness can unwittingly distribute this around an office by the simple process of breathing. If the air-borne particles are long living outside the host, these particles can be widely distributed. The first defence in the air-conditioner is the air filter, which ordinarily is only designed for large debris particles, such as fluff, skin scale or other relatively large particles.

Secondary defence is by running the cooling coil as a 'wet-coil' so that smaller debris is caught by the wetness of the coil. If these measures are considered inadequate, then other processes can be utilised. The air filter can be upgraded to a pollen catching potential or in extremis absolute filters of the HEPA type. For more direct action the air can be passed over 'Ultra Violet Light' tubes, which when designed correctly will kill the vast majority of bacteria. These are a specialised device and can be readily used in the smallest to the largest air moving equipment.

HUMIDITY.
Generally speaking, the air quality in the UK is normally between 45 – 55% RH, in which we all feel fairly comfortable. Too low an RH and we feel too cold and have the 'dry-throat' or 'dry-eye' effect, too high and we tend to feel stuffy or lethargic, as the ease that we can sweat to cool our skin is diminished. In certain cases, too low an RH can result in built up of static electricity in electronic equipment and this can have a devastating effect on delicate electronics, if not properly dealt with.

Small office air-conditioners can have a dehumidify function – generally speaking the control symbol is a water droplet, although most manufacturers disable this function in the UK. So in offices or applications with multiple small conditioners, these require a separate humidifier to add water vapour to the room if the RH drops too low. On the bigger air-conditioner ventilation systems it is usual in incorporate humidifiers or de-humidifiers inside the plant equipment and to control the air quality at the point of delivery.

AIR QUALITY (Maintenance Regime).
This is an imperative to take care of installed equipment, even though most aspects, of which is overlapped with the two previous headings. However, it is a general consideration that good maintenance and cleaning is employed. Your installer or the manufacturer can provide this service, by phone or e-mail arrangement. Blocked air-filters can cause poor performance and increased running costs. Failure to treat water collection trays may sometime result in 'wet dog' odours emanating from the air-conditioner, due to harmless bacteria producing methane gases (marsh gas). It is, in any event, better to have a pro-active approach rather than a reactive approach as it will be, generally speaking, cost effective over the life of the equipment.

www.silentair.co.uk

(JP)