Increasing Adapter 100mm Rigid To 125mm Flex


£18.00 £21.60 (inc VAT)

In stock

Product Description

Increasing Flue Adapter 125 Rigid to 150 Flex

Model: 20-100-MR

Increasing Adapter 100mm Rigid To 125mm Flex connects the flexible chimney liner (one diameter size bigger – ie. 5 inch (125mm) to single wall pipe at the base of the stack.


Connects 125mm (5 inch) flue liner to 100mm (4 inch) black pipe / vitreous enamel / 1mm stainless / single wall flue at the bottom of the chimney stack.

HETAS recommend that if you are burning wood then you should increase the size of the flue liner by 25mm from the appliances spigot size. This is due to the amount of condensates that can be produced from burning unseasoned wood.


Made from 316 grade stainless steel, it has integral drain hole to let the condensates flow back into the flue.

Installation Check List

Connect the bottom of the flue liner to the adapter’s twin wall section, using self tapping screws and seal with either fire cement or high temperature silicone sealant.

You can now conect the adapter using fire cement or high temperature silicone sealant to either your appliance (if the appliance is a solid fuel appliance then you must have a least 600mm of flue pipe before this connection) or black Pipe / vitreous enamel / single wall stove pipe.

If the gap is large between the adapter and the pipe you can seal using a combination of fire cement / silicone and fire rope.



Additional Information

Weight 5001 g

Flues & Fittings


5 Inch (125mm) Flue Liner


Flexible Flue Liner


4 Inch (100mm) Vitreous Enamel


Vitreous Enamel Single Wall Flue







Local Pick Up           Free

England & Wales    £2.99

Scotland From        £3.99

Unfortunately we do not deliver to Ireland, Scottish Islands and Isle Of Wight.

If you need more infomation regarding delivery, please call 01843 842727 Mon to Fri 8am to 5pm.