Wood-Burning Stoves and Flues: 01792-472692

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Stove Questions and Answers

Document J  (Building Regulations 2010)

Frequently Asked Questions

Q: What is the best fuel to use in my stove?

Wood burns best on a bed of its own ash, and a multifuel stove has a riddling grate to allow ash to fall through, coal prefers to draw from beneath itself.

Depending on the stove model, you can let the ash build up in a multifuel stove, and avoid riddling the grate; this then allows for better wood burning performance.

If you are only ever going to burn wood, get a wood burning stove which is cheaper and better suited to the task. If you are going to burn both, a multifuel stove will cope admirably if you help it along - hence its name!

Efficiency

Q: A friend changed his open fire for a multifuel stove. His room is now so much warmer than it was previously. He also told me that his stove uses a lot less fuel than his old open fire. I am now thinking about getting a stove myself, but am curious as to how this small stove created so much heat.

The first thing to point out is that an open fire has a lesser output efficiency, The reason for this is that the chimney for an open fire draws a great deal of air from the room to feed the open fire, This hot air is mainly drawn up the chimney, which results in a lower heat output into the room itself.

A stove however is directly connected into the chimney by means of a flue pipe. This pipe can vary from a 100mm to 200mm depending on the size of the stove and the room in which it is sited. This pipe is sealed into the chimney by means of a register plate. The sealed connection allows air to feed the fire which passes through small vents or adjustable wheel valves at the bottom of the stove. A stove also has a baffle plate, which with the small inlet air valves helps to create a great draw into the chimney.

The stove heats up internally and then acts as a radiator does, which results in heating the room quickly and also efficiently, instead of heat loss up the open chimney as in an open fire. The fire is also controllable as you are controlling the air intake to feed the fire. Once a comfortable room temperature is achieved, the air intake is closed down and the stove radiates the heat for hours without the need for refuelling, hence the saving of fuel and high efficiency of over 75% and up to 85% is reached in quality cast iron stoves.

Register plates

Q: Must a register plate be fitted into my chimney opening before my stove is fitted or can I leave the stove pipe inside the chimney liner unsealed?

It is essential that you fit a register plate for the following important reasons.

A stove only operates efficiently when the air being drawn into the chimney comes through the stove air inlets. Where a flue pipe is not correctly sealed into a chimney air will be drawn up into the chimney from the room, as warmer air always convects towards the cooler air outside if the pressure differential is correct. This plays havoc with a stove’s air system and causes really poor draw from the stove, this results in gases from badly burnt fuel leaking into the room. This can be lethal as carbon monoxide (which is odourless) is one of the gases which results from poorly burnt fuel this can obviously have devastating consequences.

A professional stove fitter such as a registered Heta engineer must install your stove and receive a certificate to show that your stove has been properly installed.

Q: I recently had a stove installed, with 1.5 metres of black stovepipe (which can be seen). The pipe has one narrow end, and a flanged end. It has been fitted with the flanged end pointing upwards and the narrow end pointing down. Has this been fitted incorrectly?

NO your stovepipe has been fitted correctly.The narrow end should be fitted inside the stove spigot or connection terminal and sealed to avoid any gas spillage or extra air intake into the flue. One advantage of the flanged end pointing upwards is that any condensation or rain that runs down the inside of the stovepipe will be evaporated by the heat of the stove, and will not seep out of the joint if fitted the other way round. It is also reduces friction to the emitting gases and also reduces air being drawn into the flue system. It is important to have these exposed stove pipe joints sealed with a thin layer of black high temperature sealer to ensure total air tightness.

Small fireplace openings

Q: I can not achieve the recommended clearances around the sides of my stove. Can I still fit it?

Most manufactures will recommend a minimum of 150mm clearance between the stove and the non combustible sides of any fireplace opening. The reason for this is to help the heat radiate into the room and not the chimney sides, and to help the heat get away from the stove body. Should the stove be squeezed into a small opening you will heat the internal chimney walls, this will lead to inefficient heat output into your room and reduce the stove life expectancy. Ideally the opening should be made bigger to suit your stove.