A major part of keeping your indoor air healthy is your HVAC filtration system. Filters work by capturing dust and particulates in the air as it flows through your HVAC system and they’ll only perform as specified if they are regularly cleaned and correctly maintained. If well maintained, HVAC filters will also help protect expensive components like cooling coils, condensers and ducting from corrosion – preventing costly HVAC remediation projects.

Queensland is well-known for its hot and humid climate so it’s especially important in our region to be aware of the relative humidity inside your ductwork. When humidity reaches dewpoint, condensation will occur in your HVAC system. Coupled with accumulated dirt and dust, bacteria and mould start to grow. Some of the common places this occurs is on acoustic duct liners, in your Air Handling Unit (AHU) and in supply ducts.

Air Restore has over 14 years’ experience managing HVAC hygiene and restoration projects including filter maintenance, filter installation and filter bank upgrades. 

We can assist with:

  • Writing filter monitoring and maintenance schedules
  • Testing air filters, and can organise NATA approved testing for HEPA filters
  • Filter bank upgrade projects
  • Filter installation
  • Filter cleaning
  • Filter restoration
  • Filter frame replacements

Filter Installation and Upgrades

After the correct air filtration system and filter media have been specified it’s important to ensure that they have been installed correctly and tested to confirm they are fit for purpose.

This is to identify any areas for potential air to bypass the filter media and cause contamination in your HVAC systems’ housing, coils, fans and ductwork. Getting a snapshot of your system working correctly at an early stage of the project will help pinpoint any potential problems, avoiding future issues and also assist in the development of your filter maintenance schedule.

During filter installation and upgrade projects Air Restore will ensure project compliance by:

  • Visually assessing the quality of the filters prior to installation. Your air filter product supplier and manufacturer must ensure that filters meet the relevant Australian product standards and safety requirements. Filter media should be supplied free from damage such as rips, holes and tears, and be well-sealed within the frame. If necessary, Air Restore can document location of all filters to assist with your regular filter maintenance schedules.
  • Correctly installing the filters according to airflow direction and filter type.
  • Ensuring that filter fasteners are in place, and correctly installed. Filter fasteners are a particularly cost-effective preventative maintenance measure, and especially important when your HVAC system has been designed for filters to be serviced from the downstream side.
  • Checking the bank of filter frames are rigid and well-reinforced. This will help to improve the life of your filters by preventing them from collapsing and collecting moisture, which leads to mould contamination. At the point where there is visible mould, or presence of virus and bacteria on your filters they are spreading mould and bacteria throughout the air in your building and will need to be immediately replaced.
  • Caulking any cracks between filter frames / bank of frames and the duct wall to prevent unfiltered air bypassing your filters.
  • Checking filter holding frame seals, gaskets, fasteners and filters are correctly sized to match the filter holding frame. This will prevent bypass air.
  • Assessing the specified filtration system to predict any areas of potential air bypass or mould contamination. These can be marked on building drawings and used to assist with your on-going filter maintenance schedule.

Filter maintenance – scheduling and monitoring

Once your filters have been installed and tested to ensure that they are operating effectively, they need to be monitored and maintained so that they continue to trap dust and contaminants and don’t affect supply fan capability or lead to blow-outs.

One of the best ways to manage your filters is to use an automated early warning system. A differential pressure measurement device can be installed across your filter bank to monitor air pressure drops. It’s more accurate than relying on a visual inspection. High-efficiency filters will often look dirty, but still operate at efficient levels, as the particulates they prevent from becoming airborne are often too small to see with the naked eye.

The opposite is also true, you can have a filter that looks clean, but isn’t operating at optimum levels because of a small tear or moisture build-up that has weighed-down the filter, pulling it away from the frame edges and allowing air to bypass.

As the filter media loads up with particulates it becomes more efficient at particle removal, the downside of this is that it increases pressure drop and reduces air flow throughout your HVAC system.

All filters will have a point in time at which they become overloaded. They will become deformed, pull away from the frame edges, unload dust into the air and in extreme circumstances ‘blow out’ of the filter rack – leaving large passages for unfiltered air to bypass. Overloaded filters not only cause unhealthy air to circulate through your building, they also lead to clogged coils, dirty ductwork and can affect the flow capabilities of your HVAC fans. 

If you’re particularly concerned about mould and bacteria growth in your HVAC unit, whether you’ve had re-occurring problems, are recovering from water damage or are in need of sterile air conditions for a lab or operating theatre, Air Restore can organise for periodic testing of your filters to monitor mould or bacteria growth.

Keeping track of pressure differentials and monitoring changes over time will help you build a maintenance program that is specific to your building and the needs of your occupants.

What are the typical problems with air filters?

It can depend on the building, but one of he most common issies we see is that filters have moved away from the side of the frame – and that allows air to bypass the filter. The simplest and cheapest way to fix that is to use filter clips.Filter clips are easy to install, and you shouldn’t need specialised tools to secure them.

How often do I need to clean my air filters?

Your filter maintenance schedule will be dependent on factors like … so it will be specific to your site.

We recommend that you carry out the filter cleaning schedule yourself, once you have the correct info collected from… In fact when we look for evidence of a filter maintenance schedule/ 

If you haven’t currently got …
The thing is there are a lot of variables that will impact your HVAC cleaning schedule. The only real way to determine your duct cleaning schedule is by inspecting it regularly. You can carry out the inspection yourself, in fact we recommend that it be included in your system or building maintenance schedule. Please be aware that this inspection and assessment of HVAC Hygiene doesn’t override essential services or maintenance requirements that apply.
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