Flue systems for gas fires
Suitable for:
- Domestic gas fires
- Up to 7kW heat input
Dunbrik Mini Clearflow Gas Flue Block System
This is a neat efficient method of providing a flue in a new domestic dwelling. Gas fires suitable for “pre-cast flues” may be fitted. The outlet depends upon the house design. It is usually through twinwall flue pipe in the roof space to a ridge vent or to a gas terminal at eaves or through the roof slope.
The gas flue blocks are built and bonded into the inner leaf blockwork of an external wall, into a party wall or partition wall.
The gas flue blocks are designed for ease of installation. The tongue and socket detail provide a tight concrete-to-concrete internal joint and an external compressive seal using special heat resistant sealant. The bonding nib has a 10mm cut-out for mortar jointing with the adjacent blockwork – this assists coursing.
System details and design guidance
The Dunbrik A1 Concrete Flue Liner Systems are used in the construction of domestic chimneys suitable for all types of domestic fires. A domestic chimney is a structure made with a minimum of 100mm thick masonry lined with purpose made flue liners. Householders can burn any domestic fuel including coal and properly seasoned wood or install any domestic gas fire including flame effect fires.
Flue Liners
Dunbrik concrete liners are made with tongue and socket joints for accurate location and tight jointing. They are manufactured from kiln burnt aggregate and Portland cement and are designed to withstand repeated temperature fluctuations.
Flue liners should be joined with Dunseal fire proof mortar paste. Allow approximately 3 joints per cartridge for 200mm liners, 2 joints for 250mm & 300mm liners and 1 joint for 450mm liners. Any void between flue liners and masonry surround should be filled with Dunfil insulating infill.
Liner Standards
British Standard BS EN 1857 established performance standards for concrete flue liners for domestic chimneys.
Dunbrik liners have been tested by BSRIA and achieved the highest categories in each class as follows:
Dunbrik Type A1 – T600 N1 G D 3
Performance Data
- T600 – Temperature nominal operating temperature 600°C
- N1 – Gas tightness negative pressure test at 40 Pascal
- G – Sootfire resistance heat shock tested to 1,000°C for 30 minutes
- D – Condensate resistance for dry flue conditions
- 3 – Corrosion resistance for all domestic fuels (scrub test for durability)
UK Building Regulations ADJ
Dunbrik A1 Concrete Flue Liners meet the minimum standards set in approved document J (ADJ) and exceed the requirements for temperature and gas tightness.
Red set wide recess starter block (3 per flue)
- Product code: 1RM
- Weight (kg): 7.5
- Width (mm): ext > 460, int. > 400
- Depth (mm): ext > 140, int. > 115
- Coursing Height (mm): 225
Red set wide gather block
- Product code: 1GM
- Weight (kg): 16.5
- Width (mm): 460
- Depth (mm): 140
- Coursing Height (mm): 225
M set deep & wide recess starter block (3 per flue)
- Product code: MS
- Weight (kg): 22.9
- Width (mm): ext > 554, int. > 450
- Depth (mm): ext > 272, int. > 220
- Coursing Height (mm): 225
M set deep & wide gatherblock
- Product code: MG
- Weight (kg): 53.9
- Width (mm): 554
- Depth (mm): 272
- Coursing Height (mm): 225
Dense backup block 100mm
- Product code: MD100
- Weight (kg): 25.6
- Width (mm): 525
- Depth (mm): 100
- Coursing Height (mm): 225
Straight bonded gas flue block 225mm
- Product code: 2M
- Weight (kg): 12.0
- Width (mm): ext > 320, int. > 185
- Depth (mm): ext > 140, int. > 90
- Coursing Height (mm): 225
Straight bonded gas flue block 150mm
- Product code: 2M/150
- Weight (kg): 7.8
- Width (mm): 320
- Depth (mm): 140
- Coursing Height (mm): 150
Straight bonded gas flue block 75mm
- Product code: 2M/75
- Weight (kg): 4.0
- Width (mm): 320
- Depth (mm): 140
- Coursing Height (mm): 75
95mm Lateral offset block gas flue
- Product code: 3ME
- Weight (kg): 12.8
- Width (mm): ext > 340, int. > 185
- Depth (mm): ext > 140, int. > 90
- Coursing Height (mm): 225
35mm Backset gas flue block
- Product code: 3MS
- Weight (kg): 12.5
- Width (mm): 245
- Depth (mm): 175
- Coursing Height (mm): 225
25mm Backset gas flue block
- Product code: 3MU
- Weight (kg): 12.0
- Width (mm): 245
- Depth (mm):165
- Coursing Height (mm): 225
125mm Backset gas flue block
- Product code: 2BM
- Weight (kg): 22.9
- Width (mm): 245
- Depth (mm): 265
- Coursing Height (mm): 260
Double tongue flue block 190mm
- Product code: 2MDT190
- Weight (kg): 7.3
- Width (mm): 245
- Depth (mm): 140
- Coursing Height (mm): 190
Gas flue block without bonding nib 225mm
- Product code: 2MN225
- Weight (kg): 7.1
- Width (mm): 245
- Depth (mm):140
- Coursing Height (mm): 225
Gas flue block without bonding nib 150mm
- Product code: 2MN150
- Weight (kg): 4.9
- Width (mm): 245
- Depth (mm): 140
- Coursing Height (mm): 150
Gas flue block without bonding nib 75mm
- Product code: 2MN75
- Weight (kg): 2.7
- Width (mm): 245
- Depth (mm): 140
- Coursing Height (mm): 75
Top exit gas flue transfer block
- Product code: 4M
- Weight (kg): 10.4
- Width (mm):265
- Depth (mm): 200
- Coursing Height (mm): 160
Top exit block with connector pipe
- Product code: 4MP
- Weight (kg): 11.0
- Width (mm): 265
- Depth (mm): 200
- Coursing Height (mm): 230
Side exit gas flue transfer block
- Product code: 5M
- Weight (kg): 24.6
- Width (mm): 285
- Depth (mm): 280
- Coursing Height (mm): 290
Side exit block with connector pipe
- Product code: 5MP
- Weight (kg): 26.8
- Width (mm): 285
- Depth (mm): 295
- Coursing Height (mm): 330
Flue block connector/adaptor
- Product code: STWBC
- Weight (kg): 0.3
- Connected length (mm): 132
457mm (18″) adjustable length
- Product code: STW18A
- Weight (kg): 0.9
- Connected length (mm): 75 to 356
Wall band 56mm spacer
- Product code: STWB50
- Weight (kg): 0.1
- Connected length (mm): –
Flue pipe 1524mm (60″)
- Product code: STW60
- Weight (kg): 3.0
- Connected length (mm): 1486
Flue pipe 914mm (36″)
- Product code: STW36
- Weight (kg): 1.8
- Connected length (mm): 876
Flue pipe 457mm (18″)
- Product code: STW18
- Weight (kg): 0.9
- Connected length (mm): 419
Flue pipe 305mm (12″)
- Product code: STW12
- Weight (kg): 0.7
- Connected length (mm): 267
Flue pipe 152mm (6″)
- Product code: STW6
- Weight (kg): 0.4
- Connected length (mm): 114
0° to 90° adjustable bend
- Product code: STW090
- Weight (kg): 0.8
- Connected length (mm): 75
Adjustable wall bracket
- Product code: STWB245
- Weight (kg): 0.3
- Additional information: adjustable to 245mm wall clearance
Adjustable flashing 5° to 30° pitch
- Product code: STWAF0530
- Weight (kg): 0.6
- Additional information: requires storm collar
Adjustable flashing 32° to 45° pitch
- Product code: STWAF3245
- Weight (kg): 0.6
- Additional information: requires storm collar
Storm collar and sealant
- Product code: STWSC
- Weight (kg): 0.1
- Additional information: for use with adjustable flashing
Gas vent terminal
- Product code: STWGVT
- Weight (kg): 0.4
- Additional information: overall height 163 mm
Ridge tile adaptor (gasket not supplied)
- Product code: STWRTA
- Weight (kg): 0.4
- Additional information: rectangular ridge tile connector
Gas flue box – Free standing
- Product code: STWFB
- Weight (kg): 4.6
Support plate and flange
- Product code: STWSP
- Weight (kg): 0.6
Firestop spacer plate
- Product code: STWFSP
- Weight (kg): 0.4
Smoke pellets – 6 per tube
- Product code: Smoke
- Weight (kg): –
- Width x Depth (mm): –
- Height (mm): –
- Info: COSHH
Flue notice plate
- Product code: Plate
- Weight (kg): –
- Width x Depth (mm): –
- Height (mm): –
- Info: A1 Chimney Flue Notice Plate Guide
Topguard steel cowl (red or buff)
- Product code: TG260
- Weight (kg): 1.6
- Width x Depth (mm): –
- Height (mm): 260
- Info: Topguard Chimney Birdguard Guide
Cannon head chimney pot (red or buff)
- Product code: Cann450
- Weight (kg): 14
- Width (mm): – Base: 300mm, Top: 280mm
- Height (mm): 450
- Info: Chimney Pots and Terminals Guide
Cannon head chimney pot (red or buff) 300mm
- Product code: Cann300
- Weight (kg): 9.2
- Width (mm): – Base: 300mm, Top: 280mm
- Height (mm): 300
- Info: Chimney Pots and Terminals Guide
Stellgas terminal – pot insert
- Product code: Stell380
- Weight (kg): 11
- Additional information: In Red or Buff. Only suitable for class two gas fires up to 7Kw heat input
- Info: Stellgas Terminal Insert
Gastyle II segmental – third round
- Product code: GTS
- Weight (kg): 8.3
- Ridge vent colour options: Antique Brown (AB), Old English Red (OE), Olive Green (OG), Slate Grey (SG), Terracotta Red (TR), Black (BK)
- Info: Gastyle II Ridge Vent Terminal Guide
Gastyle II half round
- Product code: GTH
- Weight (kg): 8.3
- Ridge vent colour options: Antique Brown (AB), Old English Red (OE), Olive Green (OG), Slate Grey (SG), Terracotta Red (TR), Black (BK)
- Info: Gastyle II Ridge Vent Terminal Guide
Gastyle II angled – 30 degree pitch
- Product code: GTA
- Weight (kg): 8.3
- Ridge vent colour options: Antique Brown (AB), Old English Red (OE), Olive Green (OG), Slate Grey (SG), Terracotta Red (TR), Black (BK)
- Info: Gastyle II Ridge Vent Terminal Guide
