‘H’ ELDFAST

Currently the definitive sealing and repair material for multifuel chimney ducts.

Safe and fit for the purpose:-

as listed under Section G in Hetas’ approval list 8:2000
as confirmed by BSRIA test certificate number 15024, Jan 2000
as approved in annex A 15459/1 to Section J of building regulations, Jan 2000
as certified independently to ISO 9002 (manufacturing process)
exceeds draft European standard pr.EN1857 as defined in BS.EN 1433:1999
Unlike many so-called ‘Ceramics’ which contain ceramic in the aggregate, this true ceramic material has a chemically-cured binder, labelled ‘Resin’.
Temperature: water-activated cement or lime-bound refractories ~ even with ceramic aggregate ~ may have a problem with the revised test procedures. The solution to lower the test temperature to 1000ºC may infer some degree of ‘sweep and fire-brigade dependency’. There may be wisdom in specifying Eldfast which has not only passed the tests but goes on to claim a 600ºC excess margin.
Acid resistance: Tested in Europe, Eldfast has exceeded the D3 standard. It claims to be inert and impervious.

Eldfast is built up to a quality and has been independently tested, whereas other redundant technologies which are still abundant are built down to a price, lack the above approvals, and provide less protection.

The average domestic flue, one brick square, will cost £98 plus vat a metre to reline with Eldfast. An underwritten guarantee(1) certificate for a nominal 10 years is issued following completion covering both materials and labour.

Limitations:- This state-of-the-art material (non-metallic) should be installed by a registered installer who can be trusted to apply the correct unadulterated mixture onto a stable clean (power-swept) surface, using an appropriate thickness and with adequate penetration into cracks and fissures, as a lining.

If incorrectly specified, while it may well reinforce an unsound structure, it may not prevent its ultimate demise, especially if the mix does not stick properly to the unsound surface.
While the thermal insulation will be greater than achieved by an unlined or conventional masonry chimney, it may not be adequate to maintain flue gases above the dew point (although any condensates formed should be contained.) Superb acid resistance should neither be exploited by condoning incomplete combustion of fuel, nor planned use in the wet condensing mode.
Whilst Eldfast should withstand chimney fires with impunity, such a build up of inflammable deposits indicates that there is something wrong with the system in the first place. As we say, “A clean chimney never caught fire.”
As with other “Tomorrow’s World” technologies, there is a temptation to take liberties rather than improve safety margins.
We do like to prevent rain going down the chimney for a couple of days before and after lining, and may use a 2kW electric heater to reduce the level of damp.

In summary:-

Most chimneys can be lined in a day, without having to break into the flue and with a minimal reduction of flue area. This is particularly appropriate for flues serving open fires that were built under former control, but also for dysfunctional, inverted, cracked or otherwise damaged conventional flue liners, including clay.

(1) The guarantee certificate is valid on condition that the renovation work is carried out by a certified Eldfast contractor. It covers the material in the flue in the event of a chimney fire, but does not cover damage by that fire to any other property (or indeed the property itself). The Guarantee is limited to the material in the flue only. Any work under the guarantee must be carried out by an approved Eldfast contractor.

To view BSRIA test certificate, click here

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