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Filter Boxes

16 products

Duct-mounted filter boxes (filter cassette boxes) for round ventilation ducting. The range is the Systemair FGR and FFR series from 100mm to 400mm, fitted inline to hold a replaceable panel filter that protects fans, heat exchangers and supply air from dust and pollen. FFR boxes ship with a BFR-M5 filter included.

Genuine Systemair, UK stock with next-day delivery available and trade pricing. Need the right box or replacement filters for your duct? Email hello@efans.co.uk or call 0161 399 3825.

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Frequently asked questions

What is a duct filter box for?

A filter box sits inline in the ductwork and holds a replaceable filter cassette, cleaning the air passing through. It protects the fan and any downstream heat exchanger or coil from dust build-up and keeps supply air clean, which matters on MVHR, supply and commercial systems.

FGR or FFR, what's the difference?

Both are circular duct-mounted filter cassette boxes. The FFR is supplied complete with a BFR-M5 filter ready to run; the FGR is the filter box housing. Choose the size to match your duct diameter, 100mm to 400mm.

Which filter grade and how often do I replace it?

These boxes take BFR panel filters, commonly M5 (medium) grade for general supply and extract; finer grades are available where cleaner air is needed. Replace filters when they discolour or airflow drops, typically every 6 to 12 months depending on the environment. Keep spare BFR filters on hand.

Replacement Filters Ventilation & MVHR Filters Duct Connectors & Fittings

Showing 1 - 16 of 16 products

Systemair FGR Filter Cassette Box - eFans Direct Ltd

Systemair FGR Filter Cassette Box - eFans Direct Ltd

Product data sheet

In stock

Next day delivery
available

Systemair

Systemair FGR Filter Cassette Box - 100mm

100mm
Panel filter cassette
G3 filter fitted

In stock

Next day delivery available

£89.99

Systemair FGR filter cassette box for ducting, 125mm size, shown in a close-up image highlighting its construction and filter area.

Systemair FGR filter cassette box for ducting, 125mm size, shown in a close-up image highlighting its construction and filter area.

Product data sheet

In stock

Next day delivery
available

Systemair

Systemair FGR Filter Cassette Box - 125mm

125mm
Panel filter cassette
G3 filter fitted

In stock

Next day delivery available

£94.99

Systemair FGR Filter Cassette Box - eFans Direct Ltd

Systemair FGR Filter Cassette Box - eFans Direct Ltd

Product data sheet

In stock

Next day delivery
available

Systemair

Systemair FGR Filter Cassette Box - 150mm

150mm
Panel filter cassette
G3 filter fitted

In stock

Next day delivery available

£98.33

Systemair FGR Filter Cassette Box - eFans Direct Ltd

Systemair FGR Filter Cassette Box - eFans Direct Ltd

Product data sheet

In stock

Next day delivery
available

Systemair

Systemair FGR Filter Cassette Box - 200mm

200mm
Panel filter cassette
G3 filter fitted

In stock

Next day delivery available

£104.99

Systemair FGR Filter Cassette Box - eFans Direct Ltd

Systemair FGR Filter Cassette Box - eFans Direct Ltd

Product data sheet

In stock

Next day delivery
available

Systemair

Systemair FGR Filter Cassette Box - 250mm

250mm
Panel filter cassette
G3 filter fitted

In stock

Next day delivery available

£118.99

Systemair FGR Filter Cassette Box - eFans Direct Ltd

Systemair FGR Filter Cassette Box - eFans Direct Ltd

Product data sheet

In stock

Next day delivery
available

Systemair

Systemair FGR Filter Cassette Box - 315mm

315mm
Panel filter cassette
G3 filter fitted

In stock

Next day delivery available

£142.99

Systemair FFR Filter Cassette Box Duct Mounted Circular - eFans Direct Ltd

Systemair FFR Filter Cassette Box Duct Mounted Circular - eFans Direct Ltd

Product data sheet

In stock

Next day delivery
available

Systemair

Systemair FFR Filter Cassette Box Duct Mounted Circular With BFR-M5 Filter - 125mm

125mm
Bag filter cassette
M5 bag filter included

In stock

Next day delivery available

£162.99

Systemair FFR Filter Cassette Box Duct Mounted Circular - eFans Direct Ltd

Systemair FFR Filter Cassette Box Duct Mounted Circular - eFans Direct Ltd

Product data sheet

In stock

Next day delivery
available

Systemair

Systemair FFR Filter Cassette Box Duct Mounted Circular With BFR-M5 Filter - 150mm

150mm
Bag filter cassette
M5 bag filter included

In stock

Next day delivery available

£163.99

Systemair FFR Filter Cassette Box Duct Mounted Circular - eFans Direct Ltd

Systemair FFR Filter Cassette Box Duct Mounted Circular - eFans Direct Ltd

Product data sheet

In stock

Next day delivery
available

Systemair

Systemair FFR Filter Cassette Box Duct Mounted Circular With BFR-M5 Filter - 100mm

100mm
Bag filter cassette
M5 bag filter included

In stock

Next day delivery available

£181.99

Systemair FGR Filter Cassette Box - eFans Direct Ltd

Systemair FGR Filter Cassette Box - eFans Direct Ltd

Product data sheet

In stock

Next day delivery
available

Systemair

Systemair FGR Filter Cassette Box - 355mm

355mm
Panel filter cassette
G3 filter fitted

In stock

Next day delivery available

£184.99

Systemair FGR Filter Cassette Box - eFans Direct Ltd

Systemair FGR Filter Cassette Box - eFans Direct Ltd

Product data sheet

In stock

Next day delivery
available

Systemair

Systemair FGR Filter Cassette Box - 400mm

400mm
Panel filter cassette
G3 filter fitted

In stock

Next day delivery available

£197.99

Systemair FFR Filter Cassette Box Duct Mounted Circular - eFans Direct Ltd

Systemair FFR Filter Cassette Box Duct Mounted Circular - eFans Direct Ltd

Product data sheet

In stock

Next day delivery
available

Systemair

Systemair FFR Filter Cassette Box Duct Mounted Circular With BFR-M5 Filter - 200mm

200mm
Bag filter cassette
M5 bag filter included

In stock

Next day delivery available

£206.57

Systemair FFR Filter Cassette Box Duct Mounted Circular - eFans Direct Ltd

Systemair FFR Filter Cassette Box Duct Mounted Circular - eFans Direct Ltd

Product data sheet

In stock

Next day delivery
available

Systemair

Systemair FFR Filter Cassette Box Duct Mounted Circular With BFR-M5 Filter - 250mm

250mm
Bag filter cassette
M5 bag filter included

In stock

Next day delivery available

£244.99

Systemair FFR Filter Cassette Box Duct Mounted Circular - eFans Direct Ltd

Systemair FFR Filter Cassette Box Duct Mounted Circular - eFans Direct Ltd

Product data sheet

In stock

Next day delivery
available

Systemair

Systemair FFR Filter Cassette Box Duct Mounted Circular With BFR-M5 Filter - 355mm

355mm
Bag filter cassette
M5 bag filter included

In stock

Next day delivery available

£255.99

Systemair FFR Filter Cassette Box Duct Mounted Circular - eFans Direct Ltd

Systemair FFR Filter Cassette Box Duct Mounted Circular - eFans Direct Ltd

Product data sheet

In stock

Next day delivery
available

Systemair

Systemair FFR Filter Cassette Box Duct Mounted Circular With BFR-M5 Filter - 315mm

315mm
Bag filter cassette
M5 bag filter included

In stock

Next day delivery available

£270.55

Systemair FFR filter cassette box for duct mounting, circular design with BFR-M5 filter, 400mm size for HVAC ventilation systems.

Systemair FFR filter cassette box for duct mounting, circular design with BFR-M5 filter, 400mm size for HVAC ventilation systems.

Product data sheet

In stock

Next day delivery
available

Systemair

Systemair FFR Filter Cassette Box Duct Mounted Circular With BFR-M5 Filter - 400mm

400mm
Bag filter cassette
M5 bag filter included

In stock

Next day delivery available

£300.99