Vermiculite and perlite granules in 100 litre bags to insulate a stainless flexible liner in a chimney, non-combustible A1, rated to 1000 °C (perlite 800 °C). The granules are light and fibre-free and you pour them straight into the flue from the top, around the liner. The flue stays warm, the stove draws better and less soot and condensate builds up.
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Which grain?
| Code | Grain | Bag | Max. temperature | Use |
|---|---|---|---|---|
| VERMK1 | vermiculite fine, 0-1 mm | 100 litres | 1000 °C | narrow gaps, insulating plaster |
| VERMK3 | vermiculite medium, 0-5 mm | 100 litres | 1000 °C | backfill around a stainless flexible liner |
| VERMK4 | vermiculite coarse, 4-10 mm | 100 litres | 1000 °C | large voids, wide chimney flues |
| VERMK3M | vermiculite mortar, 0-3 mm | 50 litres | 1000 °C | insulating mortar, sealing the top of the chimney |
| PERLKA | perlite, 0-5 mm | 100 litres | 800 °C | loose fill, lightweight mortar |
How many bags?
Take the cross-section of the flue minus that of the liner, times the height. Example: flue 20 x 20 cm (0.040 m²), stainless flexible ø150 (0.018 m²), height 8 m: 0.022 m² x 8 m = 0.18 m³ or 180 litres. Add 10 % because the granules settle: 2 bags of 100 litres.
How to order
1. Pick the grain in the table. 2. Work out the number of bags. 3. Order the stainless flexible liner and fittings in the same order. The granules are not in stock: delivery time 5 to 10 working days. Questions? Mail info@ventichim.be.
Frequently asked questions
Vermiculite or perlite around a liner?
For a wood stove or open fire we recommend vermiculite: it is rated to 1000 °C, perlite to 800 °C. For a gas or condensing boiler perlite also does the job.
Which grain around a stainless flexible liner?
Usually grain 3 (medium, 0-5 mm). It runs easily between liner and flue. Coarse is for wide flues, fine for narrow gaps.
How do I close the top of the chimney?
With a top plate around the liner or a layer of vermiculite mortar, so rain cannot reach the granules.
Can the granules get wet?
No. Vermiculite absorbs water and then insulates less. Keep the bags dry.
