Gemini Twin Fans



The Vent-Axia Gemini range of run and standby fans offers high performance double inlet forward curve fan motor impellers, typically suitable for high system resistance installation. In the event of failure the standby fan is operated, and visual fan failure indication (via integrated or optional remote indication light) is illuminated. The surface mounting model has a styled cover. For flush or duct mounting the power pack and back plate assembly is located within a galvanised steel casing and fitted with either a PVC cover for flush mounting or a galvanised steel cover for connection to ducts.

The Gemini range has an integrated overrun timer function fitted as standard, enabling versatile operation to comply with the Building Regulations Part F1 for internal rooms and Local Authority specification. The overrun timer can be manually adjusted between 1 and 20 minutes. (Units are factory set with the timer set to approximately 20 minutes).

All models incorporate a basic power pack which includes the motor housing, power on, fan run and fan fail neon indicator, which allows you to install the back plate at the first fix stage and plug in the power pack when the unit is ready for use. The power pack is pre-wired and incorporates a plug in arrangement for fitting to the back plate.

Model Range

Gemini Surface - GTFS
A surface mounted twin fan model with 100mm spigot.
Stock Ref No: 457479
Gemini Recessed - GTFF
A flush mounted twin fan model for recessed applications.
Stock Ref No: 457480
Gemini Duct - GTFD
A twin fan ducted model for in-line applications.
Stock Ref No: 457481


100mm Wall Fitting Kits (White)
100mm Wall Fitting Kits (White) For installing into most walls using the telescopic liners supplied.
Stock Ref No: 254102
Quick fix 100mm Wall Grille (Ivory)
Quick fix 100mm Wall Grille (Ivory)
Stock Ref No: 563521
Vent-cowl for connection to 100mm rigid pipe
External termination for 100mm diameter rigid ducting through roofs and walls in exposed situations. Overall diameter 200mm. Not suitable for use with flexible ducting. Features & Benefits:
  • Material: grey PVCu.
Downloads Catalogue Pages
Stock Ref No: 561403
100mm Flexible Ducting (6 metre)
Stock Ref No: 566604
Condensation trap for 100mm rigid duct
100mm Condensation trap, for fitting in vertical rigid PVCu pipe ducting. Must be used where pipe ducts pass through unheated roof voids. Fitted with 20mm pipe connection for running off condensate. Not suitable for use with flexible ducting.
Stock Ref No: 563516
Model: 563550
Ambient Response Humidity Sensor
Self programming electronic On/Off wall mounted humidity sensor which reacts to any rapid increase in humidity and temperature. Night time RH increment setback feature.
Stock Ref No: 563550
Thermo Switch
Automatically switches on fans on either a rise or fall in air temperature. Can be used for Trickle/ Boost operation on either intake or extract systems. Setting range: +6°C to +30°C. Two internal range limit/locking rings are included to allow setting within a limited temperature range or locking at a fixed set-point. IP20 rated. Sealed sensing mechanism. Mounting direct on surface only. Dimensions: 80 x 104 x 36mm (H x W x D).
Stock Ref No: 563502B

Product Specification

The Vent-Axia Gemini range is designed for installation in kitchens and utility rooms. Surface, flush or duct mounting models are available. The units meet Document F of the current Building Regulations.

Models Stock Ref. No. Performance m³/h Sound Levels @ 3m Speed RPM Max Watts Max Amps
GTFS - Surface 45 74 79 216 43 1370 57 0.19
GTFF - Flush 45 74 80 205 44 1370 57 0.19
GTFD - Duct 45 74 81 195 46 1370 57 0.19



Surface 347 170 224 69 99 35
Recessed 385 233 366 255 98 230 35
Duct 366 233 230 36 98


Gemini Surface


Gemini Recessed


Gemini Duct



Typical Specifications

Supply and install a Gemini run and standby fan suitable for mounting in wall, ceiling or ducted applications as manufactured by

Vent-Axia Ltd
Fleming Way
West Sussex
RH10 9YX
Telephone: 0844 856 0590

The fan performance should meet building regulations of 60/30 l/s suitable for kitchens or utility rooms.


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