Over time and through use, an air handling unit (AHU) gathers dust and debris that can block filters, airflow, fans, and other parts of the AHU. It is vital that an AHU is cleaned and maintained on a regular basis, usually a couple of times a year.
If an air handling unit isn’t cleaned and maintained regularly, the indoor air quality is likely to decrease. Cleaning the AHU’s components, including parts such as the coils, panel filters, and condensate pans, will ensure the unit works at its full capacity. It will also extend the unit’s service life, improve efficiency, and ensure that the air quality is maintained at optimum levels.
AHUs can differ in size, but according to the NADCA (National Air Duct Cleaners Association), a full clean will take around three hours to complete. For the best results, it is recommended to use a certified air systems cleaning specialist who will ensure that the ductwork is also properly cleaned and there is no damage.
The cleaning regime involves:
If your HVAC system is located outside, make sure that the area around the HVAC unit is clear from any debris, such as branches, plants, long grass, and general dirt. Your AHU should also have at least two feet of clear space around it.
Using a cleaning plan, the right cleaning method needs to be selected, i.e., wet or dry cleaning, to ensure no damage occurs to the components or surfaces of the AHU. A cleaning plan will include:
Wet cleaning, for example, would be used to clean terminal devices (once removed from the ductwork), and heat recovery units if they are installed in a place where the water from wet cleaning can be drained off. This cleaning method is more suited to removing deposits that are stuck to the surfaces, like grease or oil from installation. However, wet cleaning is not usually used to clean air ducts, as they are not watertight.
Dry cleaning, usually using compressed air and hand vacuum cleaners or mechanical brushing, can be used to clean between heat exchanger fins, filter banks, silencer surfaces and any other areas where any water from wet cleaning would damage the AHU. This method removes most of the accumulated dust and dirt that has loosely settled on the components.
Cleaning robots are also useful to clean rectangular air ducts, particularly those that have a camera attached to monitor cleaning progress.
For cleaning areas that potentially contain microbial colonies or living cells, such as AHUs located in outdoor spaces where moisture is at a greater level, different cleaning methods will need to be undertaken.
When you’re ready to clean your air handling unit, make sure it is switched off before you start.
Ensure new filters have been installed and then you can test your AHU.
Turn the power to the condenser unit back on, switch your thermostat back on inside and adjust it to the cooling or heating mode you want in order to activate your AHU. If the unit doesn’t reactivate and start working almost immediately, contact an engineer to investigate the problem.
It is of vital importance to regularly maintain your AHU and air conditioning units to make sure they are in full working order and doing their job of effectively cleaning the air in buildings or rooms. This will also increase efficiency and save you money in the long term.
When the unit is not in use, cover it with plastic and tie it down with a bungee or a rope.
If you don’t feel confident about cleaning your air conditioning unit yourself, it is a good idea to hire a certified heating and ventilation engineer who will be able to clean the unit for you. At the same time, they will be able to service your AHU, making sure all parts are working correctly and replacing any parts that are damaged or need replacing.