Accessories

Frequently asked questions

What accessories do I need alongside a new fan?

At minimum, the fittings to connect the fan to the duct and something to hold the joints closed: adaptors, connectors and clips sized to the duct. Beyond that it depends on the duty. A fan that will run continuously usually wants a speed controller. A fan near an occupied room usually wants a silencer. A supply system wants a filter box. An external termination wants a back draught damper or a self-closing grille. Working out which of these apply before the fan is installed is considerably cheaper than retrofitting them afterwards.

Do I need a speed controller?

If the fan runs continuously or was sized with any margin, yes. Fans are usually specified slightly oversized to cover system losses, and left uncontrolled they then run louder and use more power than the duty requires. A speed controller lets you trim the fan to the airflow actually needed. Check the motor type first, because AC and EC need different control: AC motors take an electronic or transformer controller, EC motors take a 0 to 10V signal or a potentiometer. Fitting the wrong one can damage the motor.

What does a duct silencer do and where does it go?

A silencer is a lined section of duct that absorbs noise travelling along the run from the fan toward the room. It goes downstream of the fan and upstream of the terminal, with a straight section either side so air enters it evenly. It will not fix noise generated at the grille itself, which is a face velocity problem, and it will not fix a fan that is mechanically noisy. Allow for the pressure drop it adds when sizing the fan rather than discovering it afterwards.

When do I need a filter box?

On supply air, wherever you are drawing outside air into a building and want to keep dust, pollen and insects out of the ductwork and the occupied space. A filter box holds a replaceable panel, typically G4 for coarse dust or F7 for finer particulates. Fit it where the panel can actually be reached, and treat the filter as a consumable. A blocked filter is one of the most common causes of a system that used to work and now does not, because the pressure drop climbs steadily as it loads.

How should duct joints be fixed and sealed?

Rigid push-fit duct still needs mechanical fixing at each joint, and flexible duct needs a jubilee clip pulled tight over the spigot. Clip first, then seal. Unsealed joints leak, and leakage on an extract run means the fan is pulling air from the loft rather than the room it is supposed to be serving, which shows up as a system that passes on paper and fails on a flow measurement. Support long runs properly too, since a sagging duct adds resistance at every dip.

Do accessories need to match the fan brand?

Rarely. Ducting accessories are sized by diameter, so a 150mm adaptor will fit a 150mm spigot regardless of who made either. The exceptions are controls and anything that plugs into a manufacturer's own system: speed controllers must match the motor type and often the specific fan range, and MVHR filters are unit-specific. Where a product page names compatible models, take that as the limit rather than a suggestion.

Do you supply accessories for trade and project work?

Yes. We supply M&E contractors, installers, developers and facilities teams, and hold stock across the standard sizes for next day delivery. Send a schedule or the fan and duct details and we will list the accessories against it and price the lot, including anything consumable you will want spares of. Call 0161 399 3825 or email hello@efans.co.uk.