RBH - Centrifugal Roof Fans



Specially designed for use when high pressure characteristics are required. Centrifugal roof models are delivered on-site ready for installation, fully assembled including service isolator. The range consists of 9 sizes with duties from 0.248m /s to 4.5m /s (892m /h to 16200m /h) with high pressure development available up to 900 Pa making this range particularly suited for ducted applications.

The mounting plate is moulded with an integral fixed bellmouth to ensure optimum efficiency and precise alignment. The weather-cowl is also moulded to produce a smooth internal surface and a tough UV resistant finish. Colour: BS 10A07. Alternative colours available on request. Equally suitable for flat or inclined roofs, backward curve centrifugal roof models are suitable for kerb or purlin box mounting and feature a wide range of accessories for many different industrial applications.

Vent-Axia centrifugal roof fans are designed for either kerb or inclined fixing (max. angle 30°).


The Centrifugal roof range features a proven external rotor motor and backward curved aluminium impeller assembly selected for performance and non-overloading characteristics. The assembly is dynamically balanced to VDI 2060. The motors in this range are protected to IP44 according to BS EN 60529. Ball bearings are greased for life and are designed to run at any angle. Insulation isClass 'B' (from -30°C to +40°C). Manufacture is controlled to BS EN ISO 9001 standards.


Single phase 220-240V Hz. Capacitor start and run. Three phase 380-415V 50Hz. A service isolator switch is provided for local isolation to meet COSHH requirements. The enclosure is protected to IP65 according to BS EN 60529, except on size 250 dia where a service switch is provided.

All motors are fitted with Standard Thermal Overload Protection (S.T.O.P), which for three phase fans should be wired into all controller circuits and into starter contactors. Most models are available with 4, 6 and 8 pole motors.


Fan Size a b c d Weight Kg
250 500 500 280 90 16
315/355 700 680 410 83 16/22
400/450 800 780 480 83 24/27
500/560 950 930 575 103 35/46
630/710 1230 1055 630 103 57/73