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Twin wall flue Regulations

Twin wall flue can travel internally within a building or externally on an outside wall. Twin wall flue pipe is not difficult to fit (it all clips together using locking bands); you just have to know your Building Regulations (or let us do the design for you). The wider diameter pipe exiting the room in the next image is black twin wall flue From that point you will then usually have to change to a minimum 6 (150mm) flexible chimney liner or rigid insulated flue system. If you order a flexible liner kit or full twinwall flue system from us it will come with the suitable adaptor to connect to the 5 or 6 enamel pipe. That applies to most solid fuel appliances Twin wall flue pipe is a metal tube (flue) insulated with approx. an inch of insulation (two layers of stainless steel with insulation between). Stainless and black powder coated systems are fully interchangeable. The insulation is necessary to keep the gases hot When installing a new twinwall flue system, if the flue exits the roof within 600mm (horizontally) from the ridge (high point) of the roof then the flue must extend a minimum of 600mm above the ridge. If the flue exits the roof further down then it must extend high enough to achieve 2.3m of horizontal clearance

Installing a twin wall flue chimney - a stove installer

  1. imum of 150mm (6) before touching the first surface using the appropriate Shieldmaster Adapter
  2. As a guide a chimney that is 4.5m high (from top of stove to top of pot) should be high enough to ensure the stove has sufficient draft. With a modern twin wall system you should get away with 3.5m or even 3m if you have to (e.g. out of a shed or caravan or boat). 4
  3. A key document is the Construction Products Regulations Mandate 105 Chimney, flues and specific products It covers the requirements for all chimneys and flues to be used in any type of building

Dimensions and clearances using the Clearline AKW Twin Wall Flue System The flue must be at least 50mm from combustible surfaces, so any holes in combustible floors etc must be cut 120mm larger in diameter than the external diameter of the flue. Thus you should cut a 320mm diameter hole for 150mm double skin flue As much Single Wall pipe can be used from the stove as required (but should be kept to a minimum) but you must convert from this to Twin Wall insulated flue a minimum of 6 (150mm) prior to reaching the underside of your ceiling / roof or inside of your wall

Regulations Flue-pipes

Twin wall flue Vitreous enamel or single wall connecting flue pipe Cover Band Existing Masonry Chimney Top outlet on stove Adaptor Inspection Bends 90˚ Tee 135˚ Tee Inspection Length Tee Cap Offset no greater than 45˚ Flexible Liner Installations show are by way of illustration only Twin skin liners, manufactured from overlapping strips of high grade stainless steel to give a smooth sealed flue-way. These liners should be used with wood and multi-fuel appliances. Single skin liners must never be used with wood or multi-fuel applications. Clay, Pumice and Concrete Liners

Wood Burning Stove Installation Southampton, Hampshire

Twin wall flue : easy purchase online

Twin - Wall s ystem - Contact our sales Team: Telephone: 0844 800 6586 Fax: 01622 711 418 Introduction 1 + bout s Flue Supplies is a family-run company with over 30 years direct experience of selling chimney products to the Regulations, (again!) insist that the twin wall flue projects a minimum of 450mm below the ceiling. The transition from single skin flue pipe to twin wall flue can be aesthetically jarring and if the chosen stove suits it is worth considering bringing the twin wall down to the top of the stove and avoiding any single skin flue pipe Marine twin wall flues are constructed of a material which resists corrosion. This means it wont become dangerous over time by rusting through, as many of the old flues did. Insulated flues also improve fire safety and prevent injuries from burns. The flue gases in these types of flue stay hotter for longer

Building Regulations For Stove And Flue Installation

The twin wall chimney system must project below the ceiling in accordance to the diameter of the flue pipe. Use of an adjustable length within the flue pipe connection or twin wall chimney system immediately above the appliance, enables removal of the appliance later without dismantling the full system External Twin Wall Flue Installation Internal Twin Wall Flue Installation 20 System 2 Typical Installation Pellet Stove Installations from Mi-Flues 21 System 2 Safety/Installation/ Regulations Chimney termination heights 22 21 System Twin Wall Insulated Chimney System suitable for Condensing Oil and Condensing Gas Application Boiler flue regulations are just one type of building regulation. There are many others which determine how buildings can be constructed or modified safely and legally. As the waste gases expelled by boilers can be very harmful, boiler flue position regulations regarding boiler flues are necessarily strict Where twin wall flue passes through a cupboard, storage space or roof space a guard should be placed around it. This guard should be further away from its designated distance to combustibles. Typically this clearance distance is 50mm or 60mm, but it does vary

The twin wall flue must pass through the ceilings and roof. If the flue passes through bedrooms it should be boxed in with an inspection hatch situated in a specific place. In the loft, it will likely need some type of mesh protection. Specialised fire-stop plates, finishing plates and supports will also be used along the way The twin wall flue is essentially a flue pipe, inside another flue pipe with a layer of insulation between the two pieces. This layer ensures that the exterior of the twin wall flue does not get hot enough to cause damage to surround structures, (although it does get warm to the touch

Building Regulations For Stove And Flue Installations

As with all our twin wall flue installations, we will be guided by building regulations to determine the flue height and termination point. Consequently, from the last support, a combination of structural locking bands between the flue sections may be used. A rigid arm support kit may also be required Twin Wall Flue Pipe. A twin wall flue pipe is a system, which can safely take combustion gases produced by a Wood Burning stove and release into the atmosphere. Twin wall flue pipe systems are designed to keep the flue gases warm

Author Rob Powell Posted on 18th February 2015 9th July 2021 Categories Building Regulations, Flues, Wood Burning Stoves Tags Flue, Regulations, Twin Wall Flue Pipe, Wood Burning Stoves Leave a comment on Safe Distances to Combustible Materials Flue Diameter Twin Wall Flue Systems. In nearly every case where there is no existing chimney, a twin wall flue system is specified. As the name suggests, these consist of an internal diameter pipe (usually 150mm) through which flue gases pass and an external wall with insulation between the two layers. The insulation in a twin wall flue serves two purposes

Installation Advice

Regulations and rules for the chimney - Stovefitter's

4 500mm Length Our twin wall insulated flue is a simple push fit joint system. To create and maintain a continuous length, the twin wall pieces push together and with the aid of a locking band (provided with each length) secure the connection between each piece. The push fit system remains the easiest method of installation to date What diameter twin wall flue? HETAS regulations state that there is a minimum flue size of 150mm / 6 inch for any stove (on which wood could be burnt) unless it is Defra Exempt. Therefore, you may need to increase your flue size from your stove outlet using an increaser e.g 5 - 6 inches. Please talk to us for further information if required The twin wall flue can be fixed to the side of your building, or can be built through your ceiling up to the roof, where it can safely deposit fumes according to building regulations. Here at Trade Price Flues, we offer versatile options for those in need of twin wall flue pipe including our range of ready to go twin wall flue kits Our twin wall flue system is constructed of 50mm mineral wool insulation sandwiched between 316 Grade stainless steel 0.40mm thick inner wall & 304 Grade stainless steel 0.40mm thick outer wall. Designed for use with wood, oil, gas and low sulphur coal fuels. Installation: Simple push fit joint system, with locking band (included) Warranty: Full 25 Year Warranty include DURA TWIN WALL Dura Twin Wall is a twin-wall insulated system regulations. 1. Install the wall sleeve in a pre-prepared wall opening. Cut the wall sleeve to the desired length. 2. Place the tee piece through the wall sleeve. FLUE TWIN WALL against the faulty manufacture of th

Twin Wall Flue Economical twin wall, insulated system according to building regulations approved document J (Part F for Scotland). Can also be iron stove outlet directly to twin-wall, featuring an outer sleeve. ø A O.D. Code 127mm 103 114 2119505 152mm 103 139 211950 biomass wood boiler Agent flue regulations. Twin wall flue systems for biomass boilers | Treco. Guide to Flues and Chimneys for Biomass Appliances. Learn More. Biomass Boilers and Furnaces - Wood Stoves. Jun 12, 2021 · 800-968-8604 Toll Free 406-300-1776 Local 888-317-0987 Fax Email: [email protected] Hours 8 am - 5 pm (Mountain time. There are further building regulations when installing a twin wall flue system. Read our guide on how to have a wood burning stove without a chimney for more information. Shop All Chimney Liners Log Burner Hearth Regulations. Hearths are a very important part of your stove installation and are covered by building regulations Bit of a shame to cover up a heat radiation source within the bedroom though, albeit minimal from a twin wall flue, it'll still help keep the room warmer when the stove is burning. Use metal.

Twin wall flue system explanation, examples and diagram

Twin wall flue is suitable for internal and external installation so you can either have it run up through your house, up the outside of a side wall, or even freestanding to a height of 3m above a roof. The regulations can be strict but there's loads you can do with it,. Start by placing the first single wall flue in the stove. The junction of the two types of flue should be approx 300mm below the roof. Measure and cut the second section of single wall flue to achieve this using a slitting disc and an angle grinder. remove the flue from the stove and pack fire cement in the hole to create a seal and push the. Firstly, identify if you are taking your twin wall chimney out through the wall and running an EXTERNAL flue system up the side of your property. Or are you planning an INTERNAL flue system passing through your ceiling and roof.. Identify the kits for a HOUSE or BUNGALOW depending on your property.. Then select the kit according to the spigot location on your stove ie TOP EXIT or REAR EXIT The second option is to install a stainless steel twin wall flue system. This is a system typically used when installing a solid fuel appliance. are still prepared to provide insurance cover for the property with the installation being completed to all permitted regulations. 3. Flue Sizing. Open fires vs solid fuel appliances The connection to the twin wall system should be in the i) same room as the appliance. The system should be fully supported along its full length.j) k) Provision should be made to inspect and clean the flue. 4.5 Each joint is secured by locating the female socket end over the male spigot and twisting until it does not move. A lockin

All twin wall flue systems for biomass boilers (including log boilers, wood chip boilers, wood pellet boilers) must be installed to comply with Document J of the Building Regulations in England and Wales and part F of the Building Regulations in Scotland, as well as to the flue manufacturer's installation instructions If you are buying a Hobbit stove and would like some help and advice with planning your twin wall flue installation then contact us.We can help if you are planning on installing a small stove into a garden room, wooden cabin, shepherds hut, canal boat or even a woodland retreat.Installation applications where space is tight you should also take a look at BS 8511 : 2010 Twin flue systems are more cost and time effective for these boiler positions than concentric systems, while also complying with flue termination regulations. They offer a unique resolution for installers with tricky heating challenges New Building Regulations for Scotland. From October 1st, 2013, it will be a part of the Scottish Building Regulations to install at least one carbon monoxide alarm in every space where a gas appliance has been fitted, except for appliances specifically for cooking. An alarm must also be fitted in areas deemed high risk where a flue passes.

Generally, the twin wall flue will pass through the external wall at a 45° angle to assist with the smooth flow of gases and to allow the ease of sweeping the flue system at a later date. The external wall of the building will need to be sleeved to allow the twin-wall pipe to pass through and decorative cover plates can be installed to offer. twin wall flue system. I have installed a twin wall flue system to serve a wood burning stove, I have had a hetas engineer to sign off the work. They have said that regulations state that thelength of the 45 degree offset section of the flue must not exceed 20% of the total flue length. Due to the position of the fire I have made it 30% Our twin wall insulated flue is a simple push fit joint system. To create and maintain a continuous length, the twin wall pieces push together and with the aid of a locking band (provided with each length) secure the connection between each piece. The push fit system remains the easiest method of installation to date. Building Regulations ICID Plus Twin Wall Flue, is ideal not only for traditional stoves but also for pellet stoves, biomass appliances, mini/micro CHP and even condensing Boilers capable of withstanding positive pressure. The system is designed so that the outer case is load bearing and the inner liner is free to expand independently, therefore thermal expansion is. Twin Wall Flue Systems Whether you need a simple run of flexible flue liner to a more complex double insulated twin wall flue systems we can provide you with the flue and parts you'll require to ensure you have a chimney system that complies to current building regulations

The chimney length should be at least 2m long from flue outlet on appliance to top of chimney. Ideally it will be all straight, but if not, never with an angle more than 30º from the vertical. All chimney sections need to be effectively connected to be safe. The chimney should be adequately supported as it passes through the cabin roof to. Twin Wall flue is manufactured using 0.5mm 316 grade stainless steel for the inner skin and 0.5mm 904 grade stainless steel for the outer skin. The cavity is insulated with 25mm ceramic mineral wool. Twin Wall flue features easy to install twist lock system and parts are secured together by using a Locking Band (supplied) Midtherm HT-S is Class 1 Twin Wall insulated flue systems for medium and high temperature applications for gas, oil and solid and multifuel applications, manufactured using the latest manufacturing and welding technology ensuring high quality and value for money. HT-S is available in 125mm, 150mm, 175mm and 200mm, for larger diameters please.

How to install a wood stove chimney through a wall or roof

TWIN WALL. Jeremias is a German manufacturer of DW-ECO 316 twin-wall insulated chimney systems, engineered in both Spain and in Germany. The high-temperature resistant twin-wall system they produce is made from 304 outer (0.4-0.6mm) and 316 inner (0.4-0.6mm) stainless steel. The twin-wall system is densely packed with rigid mineral wool. Matt Black HT-S Description: Midtherm HT-S is a Class 1 Twin Wall insulated flue system for medium/high temperature, gas, oil, solidfuel and multifuel applications. Powder coated Matt Black, in a full architectural polyester powder - TGIC with a 30% gloss level. Matt black HT-S is available in 125mm, 150mm, 175mm, 200mm, 250mm, 300mm and 350mm. HT-S has a 0.5mm 316L 2B grade stainless steel. ICID Plus Twin Wall Flue, is ideal not only for traditional stoves but also for pellet stoves, biomass appliances, mini/micro CHP and even condensing boilers capable of withstanding positive pressure.. The system is designed so that the outer case is load bearing and the inner liner is free to expand independently, therefore thermal expansion is accommodated within each and every joint of the. Twin wall flue is a flue pipe inside another flue pipe with a layer of insulation between them. This prevents all the heat being transferred to the outside of the pipe, so a twin wall pipe will still get hot, but not enough to damage a building or be a fire risk

The twin wall doesn't really ever get hot. All I've done so far is cut the plasterboard back 50mm from the twin wall, and cut a hole through the kingspan just slightly bigger than the twin wall, the gap I sealed with pu foam. Any advice welcome, thanks Twin wall flue pipe is prefabricated and cannot be cut to length to fit. It needs to be carefully designed prior to fitting. Out full qualified HETAS engineer can tailor customer requirements to meet building regulations. The twin wall flue will be constructed to produce a safe chimney system for your stove Suggest as a translation of twin-wall flue Copy; DeepL Translator Linguee. EN. Open menu. Translator. Translate texts with the world's best machine translation technology, developed by the creators of Linguee. Linguee. Look up words and phrases in comprehensive, reliable bilingual dictionaries and search through billions of online translations Chimney Stove Flues, Vitreous Flues, Domestic Cooker Flues, Flues Supplier in Ireland. We are a #1 distributor of flues in Ireland. A wide range of flues and their components, including domestic flues, chimney flues, stove flues and a variety of vitreous flue components

Video: Twin Wall Flue Systems - Billing Chimney

Flue Overview We offer Single and Twin Walled Flues in both stainless steel and black. As a standard you will need a single wall flue but if you wish for you oven to be indoors or under a roof you need a twin wall flue. A Twin Wall Flue prevents the flues heat from escaping and transferring to the wall/roof the flue is exiting as well as stopping the rain getting through the roof it Is passing. Stoves Are Us provide a Free Flue System Design Service. You can either complete our online twin-wall calculator , send us a simple diagram with dimensions to fluedesign@storesdirect.co.uk A member of our HETAS trained technical team will return a quotation to you within 24 hours with the complete breakdown of the components for the flue system VTec Flue Systems 6 inch Twin Wall Insulated Stainless Steel External Flue Kit. EN1856-1 T600 N1 D V2 L50050 G50. Ordering a twin wall system can be tricky, we know this however each kit should include several essential items so that it will perform as the manufacturers intended View Shield Master & Convesa twin wall flue pipe products for trade supply today at The Flue Warehouse. Create a trade account and buy online Twin Wall 5 Gas All Weather Cowl Gas All Weather Cowl used to fit to the top of the flue system and is secured by way of a locking band. This product is for gas use and has a 10mm x 10mm mesh insert. 316 Stainless Steel. Locking Band Not Provided

How To Install A Boat Stove - Marine Heating Solution

A twin wall flue system gets rid of exhaust from a variety of appliances such as boilers, ovens and air conditioning systems. In London a twin wall flue system is a less expensive option than creating and building a chimney. What is a twin wall flue system? A simple explanation of what a twin wall flue system is it is essentially a metal pipe Twin wall flue boxing in, UK stove building regs - Stoves Online. A bedroom is a prime example where toys or the contents of floordrobe may easily come to rest against the flue/chimney. Twin wall flue can get hot enough on Building Regulations For Stove And Flue Installations - Saltfire Stove 5 to 6 Appliance Connector Vitreous to Stainless. 090323261. A top quality stainless steel, high temperature insulated twin wall flue pipe, guaranteed for 10 years against defects due to faulty manufacture. This stainless steel system consists of a 25mm high density... £34.79 INC

Single Wall Flue 316 Grade. Suitable for use with wood, gas, oil and multi fuel appliances. It can also be used as a rigid flue liner instead of flexible flue. See product. All our products are Ce Compliant and conform to section J of building regulations. Make an Enquiry Shieldmaster Twin Wall Flue Individual Components Shieldmaster is a precision engineered, twin wall insulated flue system offering a complete range of components for every type of installation. Crafted with ease of use in mind, Shieldmaster utilises a secure push fit connection which when connected using the provided locking band (where. CE Certified Volcano Plus Twin Wall Chimney 150mm (6) Internal size 200mm external. 2: We are a main distributor of Twin Wall Systems. Inner pipe material:Stainless Steel 1.4404 (316L) - 0,5mm thick Buy flue liner direct from UK Manufacturer at trade prices. Lifetime warranty on all liners, HETAS approved, buy online now A straight up double wall flue pipe assembly. This one is the sealed type. The minimum installation clearances for certified double-wall flue pipes are much less than those for single-wall pipes. Also, the maximum length of a double-wall flue pipe assembly may be greater than is permitted for a single-wall pipe. There are two general types of.

The superior safety of the twin wall flue is illustrated as follows. Research by AGA many years ago disclosed that gas wall heaters produced extremely hazardous temperatures around the flue when installed in stud walls. However, twin wall flues were found to be perfectly safe in such installations. It i Twin wall flue pipe. A twin walled flue pipe should be designed to suit the appliance and kept a suitable distance away from combustible materials (see diagram below). There should also be a guard provided where the flue pipe passes through a cupboard, storage space or roof space IL is a twin wall insulated pre-fabricated domestic gas vent manufactured in the UK by SFL. It is designed for naturally aspirated domestic gas fired appliances with a draught hood/ diverter and where the chimney is required to operate under negative pressure, dry conditions and the flue gas temperatures must not exceed 250°C Boiler flue regulations ensure that the gases being expelled don't re-enter the home, which would instantly make the flue redundant. What the boiler flue regulations say. Several things are considered within the regulations from the position of the flue to the direction it can face

The regulations state that the flue must be between 30-60cm away from any parts of the home that open up, with the exact distance depending on the size of your boiler. Temperature The gas being expelled by the flue is hot as it's generated when the boiler is burning fuel so it's important to keep it away from anything made out of plastic. Identifying a twin wall flue. Discussion in 'Builders' Talk' started by ChimneyDoc, Jun 11, 2019. ChimneyDoc New Member. I'm trying to identify the twin wall in the attached images. I need to add an extra section externally to improve the draw and make it Doc J compliant. Replacing the whole lot is not really an option as it's on an open fire. Twin wall systems for external or internal applications in (internal) diameters ranging from 4inch to 8inch in black or stainless steel finis The New Regulations for Burning Logs In Wood-Burning Stoves. Twin Wall Flue. Draught Stabiliser (Twin Wall) Draught Stabiliser (Twin Wall) Tecnoflex 316L Flexible Liner is a twin skin flexible flue liner manufactured with a 316L grade stainless steel inner skin and a 316L grade stainless steel outer skin. Both inner and outer..

Planning Permission. Fitting, altering or replacing an external flue, chimney, or soil and vent pipe is normally considered to be permitted development, not requiring planning consent, if the conditions outlined below are met: Flues on the rear or side elevation of the building are allowed to a maximum of one metre above the highest part of the. Twin Wall Flue Systems. At Hartwell we take pride in ensuring that the right product is chosen for each installation. This can be a modular twinwall flue system for applications such as: Hartwell can offer a complete design draw and install of your flue system requirements. The products that we can offer are not just manufactured in accordance. Rigid Chimney Systems. Our 10000 square foot warehouse is packed full of chimney flue systems. We keep large stocks of vitreous enamel stove pipe, single wall grade 316 pipe, and twin wall insulated chimney on the shelf, ready for immediate shipping or collection. We offer Convesa KW Pro and SFL Sflue Twin Wall Flues from stock

ICID Plus Twin Wall Flue, is ideal not only for traditional stoves but also for pellet stoves, biomass appliances, mini/micro CHP and even condensing boilers capable of withstanding positive pressure. The system is designed so that the outer case is load bearing and the inner liner is free to expand independently, therefore thermal expansion is. Twin Wall Midflex Flexible Flue Liner Midtherm Midflex is a class 1 flexible flue liner, that is produced in both 316L grade stainless steel 0.10mm thick and 904L grade Stainless Steel 0.10 mm thick. Midflex has been tested for a maximum operating temperature of 6000C and soot fire resistance. Manufactured and stocked in the United Kingdo Connecting Pipes. Various types of connecting stove flue pipes may be used to connect straight from an appliance (e.g. Wood burning or multi fuel stove / log burner) to the chimney system - this may be a chimney liner, stack or twin wall flue system. There are three types of connecting chimney flue pipe: Vitreous enamel flue pipe (black); 1mm. UK regulations require that at least 425mm of the insulated twin wall chimney projects below the ceiling before the connection to the flue pipe. As we have already mentioned, the chimney system is a much larger diameter pipe so the stepped effect so far from the ceiling is not a pretty sight Twin wall flue • Rigid insulation • Double wall systems • High Quality • CE certified • 25 Years warranty. Register. Login. User . Forgot your password? +49 9832 - 68 68 50. Phone: +49 9832 - 68 68 50. Contact. Home; Stainless Steel Chimneys. Product overview. An overview of all flue and chimney systems.

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Twin Wall Flue Scottish Stove Centr

  1. ées Poujoulat has devoted its knowledge to the improved design of chimney and flue systems for houses, apartments and industrial buildings. Ther
  2. My boiler is in my kitchen and because of our conservatory the flue runs horizontally halfway along the kitchen and out through the side wall. The flue has been boxed in by plasterboard and runs approx 2.7metre from the boiler to the wall. The box is 270mm deep and 270mm high (+2.7m long)
  3. The ideal solution for connecting the stove directly to a twin wall chimney, leaving no part of the single wall flue pipe visible when used in conjunction with our EU to UK converter pipe. Straight Pipe 150mm / 6 diameter TW Pro Twin Wall Insulated Chimney System
  4. To £80.05. Regular Price. £133.42. Add to Cart. Add to Wish List Add to Compare. Poujoulat Pipe Connection Length - 550mm. From £208.48. Regular Price. £347.47
  5. In most modern boiler applications, the flue passes horizontally through the wall the boiler is mounted on. Boilers located outside have a different flue arrangement that keeps them in line with regulations. Some boilers, especially oil burners, usually have their flue going vertically through the roof
  6. Connecting your stove to Twin Wall Flue Note: These diagrams are intended to show the relative placement of components. Installation of components must be in accordance with relevant building regulations
  7. Twin Wall Flue. GR8 Fires stock a wide range of Twin Wall Flue accessories, including Spacers, Bands, Brackets, T-Sections and Plates, in a wide range sizes (5 inch, 6 inch and 7 inch diameters). More. Shop By. Filter. Price. from £0 to £601. £0. £601. Apply price range. Eco Design
Installing twin wall flue chimney for a wood burner | How

Flue Systems, Cowls, Chimney Flue Liners, Twin Wall Flue, InstallAflame. The Construction and application of chimneys and flues is covered by building regulations and in conjunction with the relevant standards in place, the term flue or chimney are often used interchangeably but are the same ILS Residential Oil Twin Wall Flue System. The ILS Flue System has been purposely designed for internal and external use with oil fired heating equipment, burning low sulphur content 28 sec. viscosity oil, viz., kerosene. ILS is based on the design of , and manufactured to the same high quality. characteristics of the well established and. KC Twin Wall Flue - 175mm Internal Diameter - Solid Firestop Plate (T200). Twin wall flue system for use on solid fuel and gas/oil appliances. eg: wood burninig stoves, multi fuel stoves gas coal effect fires, oil and gas boiler and any solid fuel appliances View Shield Master & Convesa twin wall flue pipe products for trade supply today at The Flue Warehouse. Create a trade account and buy online Twin. wall insulated flue system fire resistance class EI 120. The DUCTFIRE M series, already successful on the market as a certified fume and heat removal system with fire resistance class EI 120, passed the tests with flying colours and also obtained the CE marking as a chimney system for emission of combustion products (standard EN 1856-1.