How to Store Wood Pellets, Coal and Briquettes: Shed, Pallets, Space per Tonne
Buying fuel cheaper in summer is only half the job. The other half is getting it to winter in the same condition it was delivered in. Pellets and briquettes turn into sawdust within days if they get damp, and coal left in the rain loses heat and freezes together. Here is how to store each type of fuel and how much space to set aside for it.
What each fuel fears
| Fuel | Main enemy | What happens | Where to store |
|---|---|---|---|
| Wood pellets | moisture, condensation | swell and crumble into sawdust, block the auger | dry room, bags on pallets, under a roof only |
| RUF, Pini-Kay, Nestro briquettes | moisture | crack, delaminate, burn worse | as for pellets: dry, on pallets, in the factory film |
| Peat briquettes | moisture, abrasion | go soggy, crumble into dust | dry shed, bags or a heap under a roof |
| Anthracite | almost nothing | when wet, freezes together and is harder to light | lean-to or shed, can be kept in a heap |
| Long-flame DG | air, sun, heat | gradually oxidises and loses calorific value; a large heap can self-ignite | lean-to, low heap, protected from rain |
How much space a tonne takes
Work out the space in advance: a season's supply on pallets arrives in one delivery and has to go under a roof straight away.
| Fuel, 1 t | Volume in bulk | Packed |
|---|---|---|
| Wood pellets | ≈ 1.5 m³ | 1 pallet ≈ 1.2 × 0.8-1.0 m, ~1.5 m high |
| Anthracite | ≈ 1.1-1.2 m³ | 40 bags of 25 kg, 1 pallet |
| Long-flame DG | ≈ 1.3-1.4 m³ | 40 bags of 25 kg, 1 pallet |
| RUF / Pini-Kay / Nestro briquettes | - | ≈ 1 pallet (96 packs of 10 kg) |
| Peat briquettes | ≈ 1.4-1.6 m³ | 40 bags of 25 kg, 1 pallet |
An insulated house of 100-150 m² needs roughly 3-5 t of wood pellets, 3-5 t of anthracite or 4-6 t of DG per season (for a calculation based on your floor area, see "How much fuel you need per season"). So pellets need 5-8 m³ of dry space, and anthracite 3.5-6 m³. If you do not have that much room, buy part of the supply now and the rest by the pallet during the season.
Wood pellets: dryness is everything
- Under a roof only. The bag protects against dust but not against moisture: water condenses inside the polyethylene if the bags stand in the sun by day and in frost at night.
- On a pallet, not on concrete or bare ground. Concrete draws moisture up from below. A pallet gives 10-15 cm of air.
- Not tight against the wall. Leave 10-20 cm from external walls: condensation forms on them in winter.
- Do not stack more than 2 pallets on top of each other. The bottom bags split, and the pellets crumble into dust under the weight.
- Big bags and bulk - only in an enclosed room or a hopper. Tipping loose pellets into a shed with an earth floor is a guaranteed way to lose the bottom layer.
- An opened bag should be used within 1-2 weeks or sealed tightly: pellets absorb moisture from the air.
Damp pellets cannot be dried out: they have swollen and lost their strength. It is better to burn such a bag straight away, a little at a time together with dry pellets, than to tip it into the hopper, where it will jam the auger. For the signs of damp pellets, see "How to check wood pellets at home".
Coal: a lean-to, a low heap, away from firewood
- Anthracite can be kept in a heap under a lean-to for years: it barely oxidises and does not self-ignite. The main thing is to keep the rain off it, as wet coal freezes into lumps.
- Long-flame DG "ages": it oxidises in air, crumbles and, after a year or two of open storage, loses part of its calorific value. Buy it for one season at a time.
- Height of a DG heap - up to 1.5-2 m. In a large dense heap the heat of oxidation cannot escape, the coal warms up and may catch fire. For a few tonnes in a shed this is unlikely, but do not compact the heap or mix it with sawdust or firewood.
- Bags - on a pallet, as with pellets. A polypropylene bag left in direct sun all summer becomes brittle and tears when carried.
- Bulk coal tipped in the yard should go under a roof straight away. If that is not possible, cover it with film so that the heap can "breathe" from below and water runs off to the side.
Briquettes and peat briquettes
Wood briquettes are the same compressed sawdust as pellets, just in large pieces. The rules are the same: dry, on a pallet, in the factory film until use. Keep the pack you are currently using in the room next to the boiler, but no closer than 1 m to it. Peat briquettes tolerate brief moisture better, but when wet they crumble and smoke heavily. Keep them in a dry shed and do not throw the bags about: the briquettes break into fines on impact.
Fire safety near the boiler
- Keep only a one- to two-day supply in the boiler room, and the main stock in a separate room.
- Keep fuel at least 1-1.25 m from the firebox door and at least 0.5 m from the boiler casing.
- Pellets and briquettes produce combustible dust: wipe it up with a damp cloth, do not blow it away.
- Carry ash out in a metal bucket with a lid and never tip it near the fuel: it stays hot for up to a day.
When it pays to buy for the whole season
Spring and summer bring the lowest prices and no delivery queues. But buying the whole supply at once only makes sense if you have dry space for all of it. Otherwise the 5-10% you save on price is eaten up by spoiled bags. A compromise: anthracite for the whole season (it does not deteriorate), wood pellets and briquettes half in summer and half in autumn. Bagged coal for smaller supplies is on the "Coal in bags" page, and how to burn it properly so your supply lasts until spring is in "How to burn coal".
Questions and answers
How much space does a tonne of wood pellets or coal take?
A tonne of wood pellets in bulk takes about 1.5 m³; in bags, it is one pallet of 1.2 × 0.8-1.0 m, about 1.5 m high. A tonne of anthracite takes 1.1-1.2 m³ and long-flame DG 1.3-1.4 m³; packed, that is 40 bags of 25 kg. For a season in a 100-150 m² house, pellets need 5-8 m³ of dry space and anthracite 3.5-6 m³.
Can coal be stored outdoors?
Anthracite can be kept in a heap under a lean-to for years: it barely oxidises and does not self-ignite, but in the rain it gets wet and freezes into lumps. Long-flame DG oxidises in air and, after a year or two of open storage, loses part of its calorific value, so it is bought for one season at a time. Bulk coal tipped in the yard is best moved under a roof straight away or covered with film so that water runs off to the side.
Can coal self-ignite in storage?
Anthracite cannot. Long-flame DG in a large dense heap can heat up from oxidation and catch fire, so the heap is kept no higher than 1.5-2 m. For a few tonnes in a shed this is unlikely, but the heap is not compacted or mixed with sawdust or firewood.
What should I do if my wood pellets get wet?
They cannot be dried out: the pellets have swollen and lost their strength. It is better to burn such a bag straight away, adding it a little at a time to dry pellets, rather than tipping it into the hopper, where it will jam the auger. To prevent this, store pellets only under a roof, on a pallet and 10-20 cm away from external walls.
How long can wood pellets be kept in an opened bag?
An opened bag of pellets should be used within 1-2 weeks or sealed tightly: pellets absorb moisture from the air. Factory-sealed bags on a pallet in a dry room keep for the whole season, but no more than 2 pallets are stacked on top of each other, as the bottom bags split and the pellets crumble into dust.
How far from the boiler can fuel be stored?
Fuel must be at least 1-1.25 m from the firebox door and at least 0.5 m from the boiler casing. Only a one- to two-day supply is kept in the boiler room, with the main stock in a separate room. Ash is carried out in a metal bucket with a lid and never tipped near the fuel: it stays hot for up to a day.
Buy the fuel covered in this article
Prices per tonne and per bag, stock and delivery across Ukraine are on the category page. For wholesale: special terms.