Cox Geelen


CoxDENS® with CONNEX3T® is a concentric plastic push-fit flue gas system with the patented CONNEXT® X3 connection. The flue gas pipe is centred in the outer pipe 'pipe-in-tube' by this X3 push-fit coupling.

Safe with concentric

That is Cox Geelen’s vision into which this new innovative system perfectly fits. Carbon monoxide (CO) is an underestimated and unrecognized danger. Carbon monoxide poisoning is often caused by modern heating appliances. To reduce the risk of such poisoning, it is advisable to install a concentric flue gas system.

Advantages concentric

A plastic flue gas pipe expands more than a metal pipe when heated. Our concentric system takes account of this expansion. The expansion of the inner pipe will not lead to the break-up of the concentric flue gas pipe. In the unlikely event of a leak in the flue gas pipe, the flue gases entering the combustion air supply pipe are routed to the combustion heater. An excessively high content of recirculated flue gas will cause the boiler to shut down. 
This prevents a dangerous situation for residents.

► A concentric system thus adds an additional barrier for any carbon monoxide formed,
and prevents hazardous gas entering the living space of the home.

Especially designed for condensing heating appliances 
with a maximum flue gas temperature of 120°C (T120)




  • Available in Ø 60/100 mm in the colour white (RAL 9016). 
  • PP flue gas pipe. 
  • The outer pipe is made of plastic. 
  • The inner pipe is centered in the outer tube 'tube-in-tube' by the patented CONNEXT® X3 Push-Fit coupling. 
  • Suited for indoor installation.
  • Easy to shorten. You can shorten the outer and inner pipe in one time.
  • Less bracketing than with a two-pipe system.
  • Is not more expensive than a parallel flue system.
  • The flue gas pipe is surrounded by air, an additional safety barrier. 

Additional safety with a fire-resistant wall plate

These are round fire-resistant wall plates with integrated fireproof plate and fire protection seal. With these revolutionary wall plates you can neatly cover an opening in the wall and also provide a fire and carbon monoxide safe situation in the home. Why round? Mounting can not go crooked and the slope of 3° is included in the design.


This is a concentric plastic/plastic push-fit flue gas system.

Can I help you?

Contact our customer service, we will be happy to help you.