Change an industrial or HVAC air filter when it reaches the manufacturer’s final pressure drop or fails inspection, not on a fixed date. No single interval works across Ghana, so check more often during the Harmattan, and look at room air conditioner filters about once a month.
Why is there no single replacement interval?
Filter life depends on the dust in your air, the hours your system runs, the filter class and how well earlier stages protect it. A filter on a dusty road in Tema can load far faster than the same filter in a sealed office. That is why “every three months” can be wasteful at one site and damaging at another.
How do you know when a filter needs changing?
- Pressure drop: the most reliable signal. Fit a gauge across the filter and change it at the recommended final value.
- Airflow and cooling: weak airflow, hot rooms or a unit running constantly.
- Visual inspection: damage, wet media, or dust bypassing the frame.
- Energy use: a loaded filter makes the fan work harder.
How often should each type be checked?
Use these inspection starting points, then adjust from your own records. Inspecting is not the same as replacing.
| Filter | Normal months | During Harmattan | Change when |
|---|---|---|---|
| Room AC / split unit filter | Monthly | Every 1–2 weeks | Dirty after cleaning, or damaged |
| Pre-filter in an air handling unit | Monthly | Every 2 weeks | Final pressure drop reached |
| Bag or compact final filter | Quarterly | Monthly | Final pressure drop reached |
| HEPA filter | Per your quality procedure | Per your quality procedure | Pressure drop limit, or a failed integrity test |
| Molecular / carbon filter | Per the manufacturer | Per the manufacturer | Odour returns or media is spent |
| Gas turbine inlet filter | Monitored continuously | Monitored continuously | OEM pressure drop limit reached |
What does it cost to leave filters too long?
A clogged filter reduces airflow and raises energy use. The US Department of Energy says routinely cleaning or replacing air filters can lower an air conditioner’s energy consumption by 5 to 15 percent. An over-loaded filter can also fail or leak, which lets dust reach coils and more expensive filters downstream.
How can you make filters last longer?
- Fit and maintain a good pre-filter to protect the final stage
- Seal gaps around frames so air cannot bypass the filter
- Keep records of pressure drop against date, so you can plan change-outs
- Stock spares before the Harmattan, not during it