Pumped Refactory Concrete

This system consists of lowering a rubber former or “sausage” down the chimney, inflating it slightly, and then pumping in a lightweight refractory concrete mix. When the concrete has set, the former is deflated and withdrawn.

As with the rigid method in the previous section, the minimum wall thickness of this system is about 20mm, reducing the flue size within the existing chimney, which may limit the type of fire or appliance which can be used.

The critical factor with this system is in the skill of the installer who must ensure the mix is correct and the former is centralised within the old flue. It is also a requirement of the Code of Practice for this system that the chimney be opened every two metres and at any bend to centralise the former. This may mean mess and disruption within the building and subsequent re-plastering and redecoration.

The installation is permanent and if properly installed and regularly swept should last the life of the building.

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