How to install a Burnall Underfloor Draught Fire

We make Fireplaces from 1920s Art Deco fireplaces and classic Edwardian fireplace and mantel designs.
This guide summarises how a Burnall Underfloor Draught Fire is installed. This is not a comprehensive guide but will give you an understanding of the work involved.

The following topics are covered:

  • Preparing the site prior to installation.
  • Obtaining a draught for the fire.
  • Fixing the Burnall.
  • Fixing a back boiler to a Burnall Fire.

Full installation instructions are supplied with the fire itself.


An incorrectly installed fire may be extremely dangerous. If in doubt, always consult an experienced fitter.


For your Burnall Fire to function efficiently and safely you need to check the following prior to installation:

The fire and fireback must be built solidly with all joints sealed.

The throat of the chimney flue must be smooth and gradually tapered, with no overhanging shelves.

If the house has a suspended floor there must be even ventilation under the floorboards.

If the house has a solid floor two 4 inch air pipes must be carried to outside walls. Alternatively a forced draught fan can be installed.

All woodwork must be trimmed back to comply with building regulations, and must be no less than 9 inches from the fire.

Although the room can be partially draught proofed, it must not be sealed. Otherwise a vacuum is formed and smoke is drawn down the chimney into the room. Draughts can be reduced by fitting the Burnall Throat Unit.

The recommended height for the fire opening is 20 inches and must not exceed 22 inches. If it is more than 22 inches the fitting of a Burnall canopy is recommended.

The fire will not work if too much air is allowed into the room, for example from a constantly open or badly fitting door, another flue in the room or an open staircase. A forced draught fan can solve this problem.

Brickwork should be dried slowly, starting with a small fire during the first seven days.

Obtaining a Draught for the Fire

Instead of drawing air from the room, the Burnall Fire relies on air from under the floor to burn its fuel. When installing the fire you need to provide a source of air via underfloor pipes.

How this is achieved depends upon whether you have a suspended floor, a solid floor or a cellar underneath.

Suspended Floors

There should be a good flow of air under the floor to prevent dry or wet rot. If there is a good flow, the 2-ft. length of air pipe supplied with the fire can be fitted so that it projects through the brick constructional hearth under under the hearth proper.

All the ventilators around the house under the floorboards must be open. Check this by looking through them. There must be holes in any dividing walls or the walls that support the joists under the floor. If there is not a good circulation of air you will need to have more ventilators fitted in the under floor air space.

Solid Floors

If the house is under construction, two 4 inch bore pipes must be laid to adjacent walls, one of which should be to the prevailing wind side.

In an existing house, if the chimney is on an outside wall a straight length of 3 inch bore pipe is run from the back air adapter to the outside ventilator.

An Outside Ashbox model will facilitate ash removal for chimneys on outside walls.

If the chimney is on an internal wall, bends are used to take the pipe to the side of the chimney.

A 4 inch pipe is then run along the skirting board from the chimneybreast to an outside wall ventilator.

The pipe is boxed in along the skirting or a rectangular duct is made in front of the skirting board.

A forced draught fan may also be required.

Under Floor Cellars

If the chimney breast running up from the cellar is not deep enough to support the firebox then two girders or an angle iron will need to be fixed in the wall, with a plate across to support the box. Alternatively a pillar to support the firebox can be built from the floor of the cellar.

The same factors for ventilation apply as for suspended floors. Also the glass in one of the cellar windows can be replaced with gauze, or holes can be bored in the top of the cellar door.

If the cellar does not have enough draught a fan will need to be installed or two 4 inch bore air pipes carried to an outside wall where the prevailing wind blows.

Fixing the Burnall Fire

The fire should be set forward 2 ½ inches into the hearth. This enhances the look of the Fireplace and increases the arc of radiant heat from the fire. If a Fireplace already exists, rather than damaging the tiles by cutting out the hearth to bring the fire forward, the fire can be fixed in this forward position using specially supplied “extended sidecheeks”. These are not suitable for convector sidecheek or some back boiler installations.

For new Fireplaces, a concrete lintel should be used over the fire opening.

In accordance with the British Standard for flush Fireplace surrounds, the opening for the Fireplace should be 33 inches high and 23 inches wide for both 16 inch and 18 inch fires.

Installation Procedure

Break out any existing fireback.

Put the new / existing Fireplace and hearth in place.

Remove the hearth and cut a rectangular notch in it if the standard Baxi cut out has not already been made.

Dig out a 14 inch hole for the Burnall Fire.

1½ inch the bottom of the hole, cut a 4 inch channel for the air pipe through the constructional hearth .

The constructional hearth is the patch of fireproof material (either a concrete, stone or tiled surface) in every wooden floored house that should appear flush with the floorboards in front of where the fire is to be fitted. If this has been removed for some reason and you are fitting a Fireplace to burn solid fuel (coal or logs) it must be adequately replaced before starting to fit the Fireplace.

The constructional hearth is there to stop the joists of the floor extending beneath the Fireplace. If they did, then they would dry like tinder and any small ember finding its way down to them from the Fireplace would cause a much larger fire than you ever intended. A constructional hearth will usually consist of fireproof material at least 6 inches deep, around 48 inches wide and extending out approximately 18 inches .

It may be necessary to cut out a small trench in front of the constructional hearth to allow the air pipe to be fitted.

Bed the Burnall Fire on 1½ inches of sand and cement.

Replace the hearth.

Check that the basket is correctly aligned with the hearth and the opening.

Fix the air pipe to the nozzle on the basket.

Put the damper tube and rod in position. Fill round the box with a weak mixture of concrete.

The bottom brick and side cheeks should then be bedded in.

The chimney throat must now be built up, to a smooth tapered finish.

Slag wool pads are then inserted into the gap between the front of the basket and the hearth, to allow for expansion of the fire.

The damper valve is placed into position from inside the fire and the damper rod fed into it.

Finally, all joints must be sealed with plastic fire cement.

Fixing a Back Boiler to a Burnall Fire

A number of factors must be taken into account when installing a boiler:

Standard sidecheeks should be used.

A block boiler should be 1 inch forward into the fire.

The flue under the boiler should be 2 inches high by at least 5 inches wide.

The flue behind the boiler should be 2 inches deep by the width of the boiler (as wide as the boiler?)

If you are installing a boiler in an existing Fireplace, which previously had a raised fire, the boiler will need to lowered.

The pipes must be connected to flow from then returning to the boiler.

The pipes must rise up to the cylinder in parallel lines.

Sharp elbows must not be used.

There should be a rise of at least 1 inch to 10 inches in the pipes from the boiler to the cylinder.

Pipes must not run through cavity walls as this will make them cool quickly.

Pipes and cylinders should be lagged to retain heat.