Cox Geelen


Product support

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Customer service

If you have any questions, please contact us. We will be happy to help you. We are available on working days from 8:00 AM to 16:30 PM.

+31 (0)43 40 99 500

Frequently asked questions

  • Is it allowed to install CoxDENS PP Flex horizontally? +

    No, it is not permitted to install the CoxDENS® PP Flex horizontally.

    The maximum angle at which the CoxDENS® PP Flex material may be used is 45°.

  • When can I use CoxDENS PP? +

    The single-walled rigid CoxDENS® PP and the flexible CoxDENS® PP Flex are both used on oil and gas-fired fan-assisted condensing high-efficiency heaters with a flue gas temperature < 120° C. 

    CoxDENS® PP is also used in our concentric product range with PP flue pipe and outer pipe in plastic, alu or stainless steel.

  • Waar kan ik Cox Geelen producten kopen? +

    Als fabrikant kan Cox Geelen u niet in alle gevallen rechtstreeks leveren.

    U kunt ons bereiken via algemeen telefoonnummer 043 40 99 500 afdeling verkoop of

    Onze medewerkers zullen u adviseren waar u het beste terecht kunt met uw aanvraag.

  • Up to what temperature can I use CoxDENS PP? +

    The maximum permitted temperature for PP materials is 120° C.

  • In what lengths are our flexible pipes available? +

    Diameter 60 mm: 12,5 - 25 - 50 - 80 meter
    Diameter 80 mm: 12,5 - 25 - 50 - 80 meter
    Diameter 110 mm: 15 and 25 meter

  • What does the 's' in PPs stand for? +

    The 's' in PPs stands for 'schwerentflammbar', i.e. flame retardant. If the PP is exposed to a source of heat and the heat source is removed, the flame extinguishes within seconds. By adding special additives, we create this flame-retardant property, making the product even safer.

  • I am a consumer, can I order from Cox Geelen? +

    No, as a manufacturer, Cox Geelen cannot deliver directly to you.

    For consumer orders, we kindly direct you to a technical wholesaler.

    Please check our website to see which points of sale you can contact.

    If you need advice, you can reach us at phone number +31 43 40 99 500 or email us at

  • How many metres of CoxDENS PP Flex may be installed on a heating boiler? +

    Please refer to the installation instruction of your heating appliance for this. However, more than 25 m is not allowed.

  • What is the difference between CoxDENS PP and CoxDENS PPs? +

    Both are single-walled systems made of PP.

    CoxDENS® PP is bright white and also UV-resistant. All diameters namely 60, 80, 100, 110, 125, 160 and 200 are in white.

    CoxDENS® PPs is translucent in colour, fire-retardant but not UV-resistant. Diameters 60 and 80 mm are translucent, larger diameters Ø 110, 125, 160, 200 and 250 mm are finished in grey.

    Both systems can be used interchangeably.

  • What is the minimum processing temperature of PP (Polypropylene)? +

    The minimum processing temperature of PP (Polypropylene) is generally above 5°C. We advise against processing PP below 5°C as the plastic becomes brittle and more susceptible to breakage or damage. This property is inherent to the plastic itself and is not related to its fabrication process.

  • Can I, as an installer, make price inquiries directly to Cox Geelen? +

    Yes, you can always make a price inquiry with us.
    Subsequently, orders and deliveries will be handled through a technical wholesaler of your choice.

    Please check our website to see which points of sale you can contact.

  • What do I need to take into account when installing CoxDENS PP Flex ? +

    The plastic flexible flue system is designed for vertical application and may be dragged a maximum of 45° from vertical. In addition, we recommend that the inside dimension of the shaft should be a maximum of 2x the diameter of the pipe to prevent siphoning. A spacer should also be placed every 2 metres to prevent premature wear due to abrasion. When the outside temperature drops below 5° C, the flexible pipe should be warmed up before installation.

    See also the installation film on this website.

    More infomation

  • What is CoxDENS Flex? +

    CoxDENS® PP Flex is a flexible PolyPropylene flue system developed for use with condensing gas- and oil-fired heating appliances. 
    In addition, it is ideally designed for structural shafts with bends and is mainly used for shaft renovations in single-family dwellings.

    Read more ›

  • What is CoxDENS? +

    CoxDENS is Cox Geelen's range of PP plastic products.

    CoxDENS is available in single-wall UV-resistant PP or flame-retardant PP, in flexible PP and in concentric assemblies, where the flue is in PP.

    It is suitable for high-efficiency, fan-assisted, gas- or oil-fired heaters with flue gas temperatures below 120°C (T120).

  • Welk merk dakdoorvoeren levert Cox Geelen voor HR verwarmingstoestellen? +

    Cox Geelen heeft de ECONEXT® dakdoorvoer ontwikkeld met een aantal bijzondere eigenschappen. Alle ECONEXT® dakdoorvoeren zijn leverbaar in de concentrische versies 60/100 en 80/125 mm en parallel in 60/60 en 80/80 mm.

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