Frequently Asked Questions

  • Can I fit a Flettner® to a fiberglass pickup truck canopy?

    Yes, a Flettner® ventilator can be fitted to most fiberglass canopies. We have multiple customers who have had great success installing the Slimline, F2000 and TCX-2 models for such applications. Whilst a truck canopy is very rigid, it is important to check the rigidity of your chosen location before installing.

  • How easy are Flettner® Ventilators to fit?

    Flettner® ventilators can be fitted in less than 30 minutes. If you choose to fit the vent yourself we provide full step by step instructions  and a video is also available. The shutter, gaskets and fitting screws are all included in the pack. For double skinned roofs we offer adapters to make installation simple.

  • Where can I buy a Flettner® Ventilator?

    We sell our products through an international network of distributors and stockists. Please complete our contact form to request distributors and stockists for your location.

  • Which model of Flettner® Ventilator should I buy?

    To find out which Flettner® is best for your specific vehicle, try entering the manufacturer and model into our ‘Which Flettner®‘ tool found on the home page!

    It all depends on your application. For small (including car-derived) vans or for vehicles, the Flettner® 2000 or Flettner® Slimline should be chosen. For large vehicles the Powerful TCX-2 is recommended.

    The Flettner® 2000, TCX-2 and Slimline LPV operate on the same principle and therefore are all highly suitable for most applications. The Flettner® TCX-2™ extracts approximately twice the amount of air for any given wind speed as the Flettner® 2000 and therefore it is usually the preferred choice where a stronger rate of extraction is required. The Flettner® Slimline LPV has a slightly lower extraction rate than the 2000, and is the natural choice when a discrete looking unit is required.

    For vehicles with roof racks, or narrow roof ribs we recommend the Slimline as it is just 58mm in height and requires a flat surface of just 70mm to be mounted.

    For buildings or other static applications we would recommend the TCX-2™ or TCX-GE because of their powerful extraction capabilities.

  • Where on my van roof is the best place to fit a Flettner® vent?

    There is a growing trend among commercial vehicle manufacturers to use thinner, lighter, high tensile steel for their body sections in order to reduce costs and improve fuel economy. To ensure trouble free operation and to avoid roof resonance it is therefore recommended that:

    • First of all you select the most appropriate ventilator for your vehicle/application.
    • The Flettner® ventilator should be fitted to the strongest section of the roof. Typically, this is in close proximity to a roof support strut and/or just before the metal profile curves down towards the drainage channel or corner
    • The Flettner® ventilator should be fitted towards the rear of the vehicle
    • The Flettner® ventilator should not be fitted centrally on an unsupported steel roof section
  • Will the Flettner® Ventilator still extract when my vehicle is stationary?

    Yes, provided there is a slight breeze in excess of 5-10mph the ventilator will continue to spin and therefore extract.

  • My vehicle has a ribbed roof, can I still fit a Flettner®?

    Yes, in the majority of cases, without any adaptation. The ventilators should be fitted to a flat section of roof. For both the TCX-2 and Flettner® 2000, the base of the ventilator should be sited on a flat ‘valley’ between the ribs. For the Flettner® 2000 and the Flettner® TCX-2™ with the standard base option, the distance between the ribs must be at least 5.75″ (145mm) wide. However, the Flettner® TCX-2™ is also available with a narrow base option allowing it to be fitted to roofs where the spacing between the ribs is as little as 4.25″ (108mm).

    For the Flettner® Slimline LPV the base of the ventilator should be sited on top of a rib on a raised section of the roof. The Slimline should be sited on a flat surface at least 2.75” (70mm) wide.

  • My vehicle has a roof rack, can I still fit a Flettner®?

    Yes! Our latest product the Flettner® Slimline LPV is just 58mm in height and has been specifically designed to fit underneath roof racks. As a result, this new product enables you to still receive all of the great benefits of installing a Flettner® Ventilator, whilst maintaining full use of your roof rack.

  • My vehicle has air conditioning – I don’t need a ventilator or do I?

    Vehicle air conditioning is a great invention. However, it does have some limitations:

    • Flettner® ventilators actively and efficiently extract stale air from within a vehicle replacing it with fresh cleaner air from outside. Air conditioning systems will not expel potentially hazardous fumes from a vehicle as speedily or effectively as a rotary ventilator.
    • Operating vehicle air conditioning significantly increases fuel consumption. Flettner® ventilators are 100% environmentally friendly. They use no energy source other than the wind. As such they are being used increasingly in electric and other low carbon technology vehicle development.
    • At more temperate times of the year, Flettner® ventilators can be a cost effective substitute for air conditioning. Flettner® ventilator shutters can be closed at the height of summer when the full effects of cooler air are needed.
    • Cooled air inside a vehicle mixed with warmer humid external air or vice versa can result in severe condensation and resultant poor visibility, mould growth and musty smells. Vehicles at the start of the working day and buses making frequent stops can be prone to this effect. The fitting of Flettner® ventilators can alleviate this problem.

    In addition, at the risk of stating the obvious, air conditioning will have no impact on the very high temperature build-up that can be prevalent in the cargo area of a van fitted with a solid bulkhead. Only a ventilator will dissipate this heat and remove any harmful fumes. Air conditioning used in vehicles to transport animals can dry the air which can cause additional stress unless carefully monitored.

  • Can poorly ventilated vehicles and buildings affect air quality and contribute to the spread of disease?

    Yes, evidence shows that poorly ventilated vehicles and buildings have higher risks of infectious disease transmission for users. Well-designed natural ventilation systems can often be more effective than air conditioning in promoting effective infection control, by increasing the number of air exchanges –


  • My vehicle has an inner lining, can I still fit a Flettner®?

    Yes, we provide adapters which have been designed to bridge the gap between the outer face of the vehicle and the inner lining. These are available through all of our main distributors. Any roof with a thickness over 9mm will require an adapter.

  • I’ve seen a cheaper copy of a Flettner® vent on the internet – All rotary vents are the same, aren’t they?

    Flettner® has been making rotary ventilators for over 80 years. We’ve learnt one or two things in that time. As with most things it is possible to cut corners to produce a cheaper product. We don’t. Before you commit to buying a non-genuine Flettner® ventilator consider the following:-

    1. Has it been thoroughly tested? We invest heavily in Research and Development to ensure that our products are fit for purpose. We use only the best designers, toolmakers and testing authorities in order to maintain our reputation for producing the highest quality ventilators on the market. The performance data of our ventilators has been independently tested by MIRA – to give our customers full peace of mind. Air extraction rates vary enormously between ventilators – make sure that you know what you are buying. We manufacture our ventilators in the UK so that we can fully monitor the production and quality control process.
    2. What is it made of? We use talc and /or glass fibre filled plastic that is UV stabilised for all key components to ensure strength, impact resistance and longevity. We could use recycled ABS plastic to cut costs but we don’t. Similarly, we only use the highest grade stainless steel for our spindles. As you would expect from the leading innovator in our field, many of our designs are patented and registered throughout the world.
    3. How long will it work for?
      Our ventilators should easily outlast the life of your vehicle. Our customers have reported Flettner® ventilators with a lifetime of over 20 years without failure fully justifying our motto – ‘Flettner® – Fit & Forget’.
    4. What happens if it goes wrong? Our products are unique in that they are covered by the Flettner® Lifetime Warranty – to demonstrate our commitment to offering only the best available product.
  • Can I fit more than one Flettner® Ventilator to my vehicle?

    Yes, and many people do fit two or more ventilators to their vehicles where additional ventilation is required such as in animal transportation vehicles which have been designed for multiple occupancy.

    When installing more than one ventilator we recommend mounting both ventilators on a strong section of the roof, at opposite ends of the vehicle if possible to maximise air extraction to all areas.

  • Can I change one model of Ventilator for another?

    Yes, it is possible in some cases. Below are the combinations possible:

    • The Flettner® Slimline can be swapped to either a TCX-2 or Flettner® 2000 – this will require you to enlarge the hole created for the Slimline to a larger one in order to accommodate the more powerful ventilators.
    • The Flettner® TCX-2 can be swapped to a Flettner® 2000 using the existing hole

    *Swapping a Flettner® 2000 or TCX-2 to a Slimline will not be possible. Also swapping a Flettner® 2000 to a TCX-2 will not work without modifications.

  • Does my vehicle require a roof ventilator by law?

    Laws vary from country to country, but the fitting of ventilation is typically mandatory when ‘Dangerous Goods’ are being transported. Under the United Nations classification scheme a whole variety of goods ranging from organic chemicals to fuels and from compressed gases to fire extinguishers are defined as ‘Dangerous Goods’.  A brief summary of the EU’s requirements for ventilation to be fitted to vehicles can be downloaded by clicking here

    In many countries the owner of a commercial vehicle has a mandatory duty of care to the driver. Thus, even when dangerous goods are not being transported, a risk assessment must be carried out and all reasonable steps must be taken to ensure that the driver is not exposed to unnecessary risks – these would include exposure to heat or fumes. If in doubt, the precautionary principle should be applied and appropriate ventilation fitted.

  • How do I activate my Flettner®’s Lifetime warranty?

    All Genuine Flettner® Ventilators purchased in the United Kingdom from an approved supplier come with a Lifetime Warranty provided you activate your warranty through our website.

    If any fault in the materials or workmanship of your Genuine Flettner® Ventilator means that the product is not of satisfactory quality, we will repair or replace it free of charge.

    The Lifetime Warranty covers the lifetime of the vehicle to which the Genuine Flettner® Ventilator was originally fitted and for as long as that vehicle remains in the ownership of the individual who purchased the ventilator. The warranty cannot be transferred to subsequent owners of the original vehicle.

    For non-vehicular applications, the period of warranty cover shall be deemed to be 10 years from the date of purchase.

    The Lifetime Warranty covers faults in materials or workmanship only. It does not cover any form of breakage or damage caused by, but not restricted to, incorrect installation, modification, inappropriate care or misuse or accident damage or if the ventilator is transferred to another vehicle.

    In addition, for non-UK customers, our lifetime warranty can only be offered if you have purchased your genuine Flettner® ventilator directly via an approved distributor and registered your warranty through our web-site.

    The Lifetime Warranty is offered as an extra benefit and does not affect your statutory rights.

    The warranty will only become valid upon satisfactory completion of the Lifetime Warranty Registration Form.

  • How does the Flettner® Ventilator prevent the ingress of water or dust?

    Flettner® products are carefully designed with an internal shield ring to prevent rain or dust from entering the vehicle or building to which they are fitted. In addition, a neoprene gasket is incorporated into the base of each ventilator to prevent water seepage. Please consult our fitting information or videos for further information.

  • How much noise do Flettner® ventilators make?

    Flettner® ventilators are designed to minimise the generation of mechanical noise. Smooth low friction bearings and a stainless steel spindle ensure quiet rotation and the wind driven operation eliminates the need for electric motors. This makes Flettner® ventilators amongst the quietest ‘active’ ventilators available. At high wind speeds the air extraction is audible, hence it is recommended that ventilators are fitted towards the rear of the vehicle and are not fitted directly above the head of the driver of a vehicle.

    The Flettner® TCX-2™ is very powerful and therefore it is recommended that this model should not be fitted to smaller car-derived vans as the strength of these ventilators may set up drumming vibrations on roof panels in certain circumstances.

  • What colours of Flettner® are available?

    Flettner® ventilators are available as standard in black or white. In certain circumstances special colours can be produced to order, if large quantities are required.

  • Where can I find full Technical Specifications and Fitting Instructions?

    These are available to download under the ‘Products’ section of this website.

  • Can I take my Flettner® through a car wash?

    Yes! With the correct installation Flettner® Ventilators are completely watertight and can be taken through a car wash. However we do not recommend directly spraying the ventilator with a pressure washer.

  • Can I fit my Flettner® Ventilator sideways?

    We advise against mounting a Flettner® Ventilator sideways. Our ventilators are fully waterproof when mounted level, however when mounted sideways we cannot guarantee you won’t experience water ingress. The bearings also may not work as effectively if the ventilator is mounted sideways.

  • Can I close a Flettner® Ventilator when ventilation is not required?

    Yes! All of our ventilators have shutters on the internal side, so you can close of the ventilation should you require.

  • What sealant do you recommend?

    We recommend any quality waterproof sealant