Fuel-burning appliances that you have that burn wood / fuel to heat your home should be vented to the outside of your home. This can be done through a chimney liner, which is the material inside the chimney flue that holds the combustion products of your burner until they exit the top of the chimney.
Flexible liners are made from continuous lengths of corrugated pipe that are installed inside the flue. Cladding a fireplace or installing a wood or fire stove does not imply any stipulation that the work cannot be done as a DIY job, but all work nevertheless has to comply with building regulations. If this work is not carried out by a competent person (for example, a HETAS installer), it should be inspected by someone from the Building Control Department of your city council. This is classified as “Construction Site” and you must notify your local city hall construction control before construction begins. In either case, there may be local planning restrictions that make the chimney work and new chimneys that you must follow. Scaffolding may need to be installed around the fireplace to the ground for health and safety reasons. Reference should be made to “Document J for Combustion Appliances and Fuel Storage Systems Approved by Building Regulations 2000 Edition 2002” or to the building control department of your local city council.
An existing chimney or a new chimney or duct installation should undergo a visual inspection to verify that it is in good condition, free of obstructions, and that it is the proper size and type for the appliance you plan to install. If you are handy with tools and have a good understanding of how chimneys and chimneys work, you may be able to do most of the cladding work yourself.
The first thing to do is check your local building and fire safety codes. In some areas, you will be asked to have a licensed fireplace specialist perform repairs or perform new siding installations for you. If you find that you are allowed to do your own work on the fireplace, be aware that replacing or installing a fireplace liner requires precision work under potentially hazardous conditions. So unless you’re sure you know what you’re doing, it would be best to let an expert handle the fireplace repair and siding installation for you. If you are confused about the best type of cladding to install on your fireplace, your local fireplace cleaning professional can provide advice during your annual fireplace cleaning.
Installing a flexible chimney liner on an existing fireplace is a two-person job.
You will need the following tools and equipment to install a flexible chimney liner on an existing chimney: a length of rope (10m), other ropes (for safety), cement, sand, integral waterproofer, unibond, trowel, hammer and cold chisel, metal scissors, buckets, old paintbrush, Phillips screwdriver, wrench and pliers, roof ladder, ladder or scaffold structure.
Before attempting to put a fireplace liner on an existing fireplace, you should always sweep the fireplace. Do not attempt to install a siding without first sweeping the chimney. Remember that debris can very well fall down the chimney at any time during the installation of flexible siding. A wood stove should be installed at the same time or shortly after a fireplace liner has been installed.
Talk to your supplier about the type of wood / fuel burner you need and the flue liner you need to serve it. The efficiency of the fire will depend on placing the correct wood burner in the correct opening and using the correct flue. If they don’t match, you could be wasting a lot of energy.
Sure, installing a flue liner on an existing fireplace can be a do-it-yourself job, but certain very important rules must be adhered to. The size of the flue used depends on the size of the flue from the wood burner. The smoke duct used must not, in any case, be smaller than the smoke outlet of the fire or stove. For a wood burner or other solid fuel fire or stove producing up to 30KW, a 150mm flue must be used. For an appliance (only burning smokeless fuel) that produces up to 20 kW, a 125 mm flue can be used. The amount of soot deposit created by a wood burner is quite considerable and in all cases a 150 mm flue is suggested. If you open an old fireplace and would like to place a wood burner in the opening, you must first arrange for the fireplace to be smoked to see if it is safe to use without a liner. If your flue requires a liner, check with your supplier for the best liner to use in your circumstances. A flexible liner is the easiest to put on.
***Make sure you stay safe while working on the roof. Proprietary roof ladders and scaffolds should be used and under no circumstances should you attempt this job on your own. It’s a two-person job.***
Now tie a large knot in the end of a rope (preferably 10mm nylon rope) and run it down the chimney to the hearth at the bottom of the chimney. Tie the other end of the string to the fireplace. If you feel the rope loosen before it hits the hearth, it has probably caught on a ledge or a change of direction in the pile. Pick up and release the rope a few times to allow it to drop. When the string is at the bottom, tie a piece of string to the top at the top of the pot or mark it in some other way. The distance between this mark and the knot that the end of the rope is the length of the fireplace liner you need to purchase. You must also measure the width and length of your pile in order to order a closure plate. The closure plate should overlap the inside edge of the masonry by about 25mm, leaving 75mm of masonry exposed around its perimeter.
Once you’ve obtained your liner, you now need to remove the pot from the fireplace and the surrounding arches. If this is done carefully, it will save the pot. Place the pot in a safe place and flatten the last 9 inches of the liner and fold the flat section on itself. Push the string through the fold and tie it under the fold. Now use some strong tape and tape the pleats together. Put lots of tape in the actual crease of the crease to smooth out any sharp edges. You’ll soon be pulling this liner down the chimney and the more times you get stuck (and we promise it will!), The more you wish you had ‘wasted’ a little more tape to round the end. Now tie a large knot at the other end of the rope and drop it once more down the chimney. When it reaches the bottom, ask your coworker to pass it while you feed it into the hole from the top. When it gets stuck, pull it up a little and pull it down again. Very few chimneys are straight up and down so there may be some curves to work with.
Check that the liner is in the correct position. There is a purple arrow sprayed on the flexible liner that should point towards the fireplace.
Chimney liner isn’t the cheapest of materials, but don’t be tempted to cut costs by being too precise with the length of liner required. It is much better to have a few to cut than to have a short 25mm. If you use stone wool insulation, wrap it around the flexible liner. You can wrap the entire siding at once or lay it section by section as you lower it down the chimney. Insulation of your flue is important. There is a long way from the wood burner to the pot in the fireplace and as the hot smoke rises it will cool on the metal of the liner. If the liner is not insulated, the hot air could condense and cause a lot of water to run through the liner and into the range. This makes the stove or fire totally ineffective. The smoke outlet is then placed on top of the wood burner. To prevent heat from escaping through the gaps, the flue outlet bracket is located in a small gap at the top of the wood burner and a piece of fire cord is placed between the two. As the flue is tightened on top of the wood burner, the fire rope is squished into place.
Connect the stove to the flexible chimney liner adapter with a length of rigid conduit and give it a minimum of 24 hours to shut down before lighting the stove. A notice plate must be completed and permanently affixed to the building when the flue pipes have been installed.
