top of page

Eldfast User Guide

Gathers / Spraying:

Please note when the material is sprayed this will create a thinner coating than will be present with the slide casting method throughout and higher up in the chimney but can be built up in stages. 


Initial Use / Curing: Solid Fuel Open Fires

Heat the flue with 2kw electric heater (or equivalent) for 12 hours after lining then 3 fires over 3 days – 
•    Day 1) Low:  Kindling fire for 2-3 hours. 
•    Day 2) Medium: 1-2kg of logs 20% moisture content or less for 2-3 hours. 
•    Day 3) High: 3-4kg of logs 20% moisture content or less for 2-3 hours. 

It is essential to carry out this firing procedure to cure the Eldfast into the flue before full use.

You may smell some smoke during the curing process while the material hardens, If this occurs finish the curing process and call your Installer if this then persists. The Eldfast lining material will become extremely hard and resilient over the subsequent months of use and exposure to normal flue gas temperatures.

Initial Use / Curing: Gas Fires 

As the gas burner or fire will not heat the flue sufficiently after lining, a gas heater of 10kw output rating should be fired into the flue by Eldfast Ltd or the trained contractor for one hour as part of the installation process (by the installer) to ensure the flues temperature is taken to 180˚C + for one hour more.  No further heating is needed.  The gas fire within the property can be used normally.


Fuel Burning

Always follow the heating appliance manufacturer’s operating instructions.

If burning solid fuel or wood ensure this is done on a bright fire and avoid slumbering conditions that create the risk of condensation and heavy soot deposits in the flue. If such deposits are allowed to occur and accumulate in the flue this greatly increases the risk of high temperature soot burn out and chimney fires that can damage the chimney and appliance.

If wood is being burnt it should be fully seasoned and air dried for 1 to 2 years under a waterproof ventilated cover open on all sides to get the maximum efficiency and reduce the risk of tar deposits. Do not burn household waste, plastics, treated timber or chemical chimney cleaners that produce harmful toxic or corrosive gases.

A moisture metre can be used to determine the correct level of 20% moisture or less is present in your wood and are readily available online or via your local 
fireplace shop.

Chimney Sweeping

It is recommended that all flue-ways be regularly checked to ensure that they are kept clean and not blocked by, for example, nesting birds. This must be carried out by a qualified chimney sweep and a record of the sweeping certificate kept with your documentation.

Solid Fuel: Should ideally be swept before, during and after the heating season or at least once a year using sweeping rods attached to a bristle brush having the same dimensions as the cross-sectional area of the flue., which should be kept in a safe place with these instructions. The Chimney must be swept a minimum once per year to maintain your warranty.


Gas fires produces less deposits in your chimney system but will still require maintenance to ensure there are no blockages. The chimney must be swept a minimum of once per year to maintain your warranty.

Creosote or soot must be removed from the flue to reduce the risk of chimney or soot fires.

If high deposits of creosote are present CreAway is recommended for treatment and removal. Please consult your local chimney sweep for details or visit our website.

External Maintenance

Any parts of the chimney exposed to weather including any terminal and flashings should also be checked to ensure that they are sound. Please also look at our range of weather protection products such as Chimney Saver and Crown Coat to extend the lifespan of your chimney.

Visit for more information.

bottom of page