Ecology Unit Carbon Filters: When to Restore Them and When to Replace Them

Many restaurants in malls, towers and residential buildings have an ecology unit on the exhaust system. It usually combines pre-filters, an electrostatic precipitator (ESP) for smoke and fine grease, and a carbon stage for odour. The carbon stage is the one people forget, until neighbours or mall management complain about cooking smells.

What the carbon filter does

Activated carbon is full of tiny pores that hold odour molecules on their surface. Air passing through the carbon bed leaves much of its smell behind. The capacity is limited: once the pores are full, odours pass straight through. Read what an ecology unit is for how the stages fit together.

Signs the carbon is saturated

• Cooking smells at the exhaust outlet that were not there before
• Complaints from neighbours, offices or building management
• The unit's service interval has passed
• Grease reaching the carbon stage because the pre-filters or ESP cells are overdue

Restore or replace?

Where the unit design allows, the activated carbon granules can be restored, which can bring back much of their odour-control performance at a lower cost than new filter panels. Replacement makes sense when the carbon is contaminated with grease, the panels are damaged, or the manufacturer specifies new media. An inspection shows which applies to your unit.

Protect the carbon by cleaning the stages before it

Grease is the enemy of carbon. If the pre-filters and ESP cells are not cleaned on time, grease coats the carbon and ruins it. Regular ESP and ecology unit cleaning keeps each stage doing its own job. HoodEx cleans collector cells, housings and pre-filters, and can restore the activated carbon in carbon filters.

Frequently asked questions