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Fireplace Installation Guide

Installation of a gas fire and fireplace


First of all you must test the existing gas supply for ‘Soundness’ This is done by using a manometer assuming the existing gas supply is sound (Showing no signs of leaks) you may then move to the next stage of the installation which is of course putting down your dust sheets and covering or removing furniture from the room you are going to be working in.  Any existing fire and fireplace can now be carefully removed and disposed of or stored carefully.  The existing chimney must now be smoke tested to confirm its suitability to accept a gas fire.  This is done by lighting a smoke bomb in the fireplace opening and checking the rooms and roof space above to check that no smoke is escaping into  the house or roof space the chimney would also have to be checked i.e. brickwork or pot etc to confirm its suitability to accept the new gas fire.  Any necessary remedial work must be done before the installation of the fire.

The next stage of the installation would be prepare the opening in the chimney breast or in the case of a balanced flue or fanned flue fire the wall on where the gas appliances is to be fitted.

The standard opening to be left to accept the gas pipe would be 25” high by 17” wide this would accommodate most gas fires but there are now many larger models on the market either to be wall mounted or hearth standing this can be determined by reading the instructions packed with the new fire to be fitted assuming it has now been prepared i.e. ‘bricked up’ and plastered as necessary we may then move on to the next stage this is of course in the installation of the hearth.

The hearth must be made of none combustible material i.e. ~Marble/granite, the base must be a minimum of 15mm thick, raised 50mm off the existing floor and in most cases protrude 300mm from the front face of the new fire and a minimum of 150mm either side of the outer frame of the new fire the hearth must be bedded down on a mix of sand and cement and levelled accordingly.

The next stage is to fit the back panel i.e. marble or Granite this would be around 37” square with a standard 22 ½” x 16 ½” opening already cut in it. The hearth is to be centralised on the new base and sealed to the wall with heat resisting silicon or similar the internal and external edges of the back panel should also be sealed with sand/cement or similar.

So as not to allow any hot products of combustion to go between the pre-paved wall and the new back panel the purpose made surround can now be fitted and secured to the wall by the appropriate fixings.

If the new fire is an inset type fire then a base must be installed in the fireplace opening to the same height as the top of the hearth this is usually done with sand and cement.

The new fire can now be fitted into the prepared opening firstly any fixing eyes must be secured to the rear of the opening which be used to secure the fire into the fireplace opening.

The gas supply must be installed in the opening usually 8mm rigid pipe works 1 metre maximum length ready to accept the fire the pipe must be factory sheathed or rapped to protect it from the effects of soot etc, it must also be merged to clear any debris before connecting it to the new gas fire.

After removing the burner from the new fire box, the box may now be secured into the fireplace opening using the new fixings and wires provided.

The burner can now be fitted and connected to the gas supply once again a soundness test must be done on the gas supply and if satisfactory may be left on and any pilot lights on the appliance relit and tested.

The gas fire can now be fired up and a working pressure test can now be done; a minimum of 19 milli-bars with other appliances in the on position is required for this.

The coals, fret and decorative trims can now be fitted and the fire must now be relit.  After 5 minutes or maximum a spillage test must now be done as per manufacturers instructions to confirm that the flue is ‘pulling’ and the products of combustion are being removed.

If the flue pull is poor then a further 10 minutes can be allowed in most cases before a retest is undertaken.  It is normal to experience an odour from the new fire, but after ½ an hour this will usually disappear.

Assuming the tests are satisfactory the customer must be shown the workings of the fire and explained the controls, battery positions etc.  The installation instructions and users instructions must be left on site with the house owners.

Dust sheets etc can now be removed and tidied.


This is for information purposes only, under no circumstances should you ever install your own fire or fireplaces.

Please find a gas safe engineer here: www.gassaferegister.co.uk