TAKING ON THE MANTLE
The creation of a functional and attractive setting for your new wood burner is a subject that is bound up with the whole installation process. This is something best left to a HETAS installation firm, but it is still an area about which you will have strong opinions, and about which you should be informed. After all, the framing of the stove is an essential element of a successful room design.
Most stoves are a retro-fit into an existing fireplace. If you have chosen a free-standing stove, it will pose no special hazards so long as you have allowed space all around it for airflow. Do ensure that your installers use a chimney plate above the stove that is made of stainless steel or fireproof board. And consult them about any danger of overheating to any wooden beam over the fireplace.
Underneath the stove the hearth must be of non-combustible material, and you may want this to be an attractive stone item, complying with the latest rules in terms of size and thickness. Your existing hearth may no longer meet the required specifications. The larger problems probably lie within the chimney, which will in most cases need to be relented with a twin-walled stainless steel flue, possibly with insulation around it. An air vent is also required nowdays.
In the case of Inset Stoves that are built in to the fireplace, there is a greater need for proper insulation of the space to avoid overheating. The installers will assess whether there need to be additional (or replacement) firebricks or other non-combustible lining materials in the recess. These stoves are also normally provided with optional outlets for heat pipes to be connected, so as to transfer warm air into the room or other rooms. You may be able to plan these pipe routes in your refurbishment scheme.
If you have a wooden fireplace surrounding it is likely to overheat and get scorched, but it may be possible to insert slate or other stone slips behind the frame to protect it. When you apply any stone or tiling facings, use plain mortar without silicon. If your opening has to be enlarged and rebuilt, ensure that fireproof plaster is used when making good.
So much for existing fireplaces: but what if you are making the inset stove fit into a new wall opening? For brick, block or stone walls, the same issues apply as for existing fireplaces. Mark out the necessary opening and flue run with masking tape, and proceed. But if you are opening up a stud-partitioned wall then you need to test where the studies are and plan to work between them or create new studies. Non-combustible spacers must be installed at least an inch away from the opening all around: with an insulating gap behind the face of the surrounding.
Make the surround and its finish of non-combustible material and attach with long screws through the air gap and into the studies. Leave gaps top and bottom to allow airflow. The base of the opening and the spacers holding the stove in place strictly must all be of durable heat-resistant materials. Modern installations often use no decorative surround, which is simple but requires protective surface material on the surrounding wall and the hidden interior facings.
Where a new fireplace is created, there are many choices of ready-made fire surrounding; ideal finishes range from cast iron to stone of all kinds (travertine, limestone, marble, granite, slate) or reconstituted stone materials. Ensure that you seal any stone or tiles to protect them against dirt and tar, then clean and re-seal them every year or so. One other possibility that is most likely to present itself in the case of new builds or major rebuilds is the ability of some wood burners to be hooked up to a back boiler to heat water.
A more advanced option is to interface it with solar panels and another backup heat source to feed a thermal store which accumulates heat from a range of sources. A skilled technician can create a system that will automatically prioritize the renewable energy units as the preferred heat sources when available.
Wood burners are increasingly being specified in new house buildings. In such cases the chimney can be built with a pre-cast pumice flue, which is a more or less permanent installation with its own insulation and requiring no future replacement so long as the chimney sweep is called in regularly.