Pellet storage options

A year's supply of wood pellets for a detached house only occupies an area of approx. 4 m². As well as the space savings, storage of the little wood pressings also offers many other benefits:

Compact fuel

Pellets have a bulk weight of at least 600 kg/m³. For a house with 150 m² of living space, approx. 6 m³ is sufficient for one year.

You only need approx. 4 m² of floor space for storage. Thanks to flexible storage solutions, this space can be located in the cellar, in a utility room or even outside the building.

Small storage space

Compared with logs and wood chips, the compact storage space required by pellets becomes even clearer. For a 150 m² house, approximately twice as much space is required to store the annual requirement of logs for central heating and DHW heating.

Convenient delivery

Wood pellets are delivered to order by tanker. The pellets are blown into your storage facility carefully and securely via a hose. It is therefore important that the tanker can park within a maximum distance of 30 metres from the inlet.

Your pellet store is replenished in a matter of minutes and your storage room is filled with the pleasant aroma of wood pellets.

Little energy giant

The cylindrical pressings made of wood waste (wood shavings and sawdust) are pressed at high pressure without chemical binding agents. With a diameter of 6 mm, they have a calorific value of approx. 5 kWh/kg.

The energy content of 2 kg of wood pellets equates to ~ 1 litre of heating oil ~ 1 m3 of natural gas. If your heating oil requirements amounted to 3000 litres per year, you would need approx. 6 tonnes of pellets for the same period.

Individual systems

The optimum means of storage and materials handling depends on the space you have available.

The traditional solution for storing wood pellets is the storage room. If no separate room is available or the available rooms are damp, then a storage tank is the ideal solution.

Direct contact with water must be avoided. Moisture causes pellets to swell up, making them unusable. However, normal humidity levels, such as those occurring in rooms throughout the year due to the weather, do not adversely affect the pellet quality.

All under control

Optionally, you can equip your storage room or storage tank with an additional level sensor. This sensor informs you of the current stock level. If the level falls below the minimum defined by you, this information appears on the boiler or as a notification on your mobile control module.

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Storage tank

The storage tank is quick and easy to install, cost-effective and dust-tight. Furthermore, the fabric is permeable to air, which makes the tank the perfect storage option for pellets. If it is protected from sun and rain, it can even be sited outside the building. Moreover, innovative storage tanks have 60 percent more storage capacity for the same space requirement.

Pellets are delivered by tanker, from which the pellets are blown into the storage room or tank by compressed air. In contrast to oil, pellets cause no unpleasant smells and are stored cleanly with accustomed convenience.

Pellet storage room

In the case of a separate pellet storage room, a smooth sloping floor with a minimum inclination of 45 degrees must always be installed. If no sloping floor is provided, the inclination is too shallow or the surface too rough, then pellets can become stuck. Not only the pellets themselves need to be high quality, but also the equipment and design of the storage room. The walls, floor and ceiling of the store must therefore be absolutely dry, as otherwise the wood pellets could swell up and fall apart.

More about storage rooms

Information and tips for the planning of pellet heating systems with storage room

The size of the storage room

The total heat load of a building determines the ideal size of the required storage room. As a rule of thumb, the following formula can be used: each 1 kW heat load = 0.9 m3 storage space (including voids). In principle, it is better if the storage room is rectangular and no wider than two metres. The narrower the room is, the lower the inbuilt inclines will be and the more space can be used.

Sloping floor

A sloping floor is the ideal configuration for a pellet store, allowing the space to empty completely. Not only does this allow for the maximum efficiency in feeding the fuel to the boiler, but it removes the need to clean the store room manually each year by avoiding a build-up of unused pellets. With a sloping floor, the pellets slide to the delivery auger in the centre of the store. ÖkoFEN can supply angle brackets designed to give the optimum angle for a sloping floor substructure.

The location of the storage room

The storage or heating room should preferably be adjacent to an external wall in order to be able to easily install the blow-in, suction and ventilation pipes. In internal rooms, however, these pipes can also be led up to the outer wall. No light switches, sockets, lights or distribution boxes may be installed in the pellet storage room.

Storage with vacuum suction system

Pellet storage and heating boiler up to 20 meters away.

Location of the wood pellet storage and the boiler room

Pellets are delivered by tanker truck and are blown into the storage room or the FlexiTank. The truck's pumping hose is max. 30 m length, so the filler coupling must be no more than 30m from the drive, parking space or road.

If possible, the FlexiTank room should border at least one exterior wall, since the filler coupling must be accessible from the outside. Where this is not possible, ventilation and filling pipes must be routed to a filler coupling on the outside of the building. (Attention - in some countries fire regulations must be observed).

The boiler room should also have at least one exterior wall in order to allow direct ventilation. For boiler rooms which do not border an exterior wall, a ventilation pipe (at least 200 cm²) must be routed to an exterior wall.

Humidity

Dry indoor conditions are a prerequisite, since the pellets would swell and became useless in contact with damp walls. In damply areas, we recommend to use our Flexilo textile silo.

Electrical requirements:

No light switches, electrical outlets, light bulbs and distribution boxes, etc. are allowed in the pellet storage room.

The measurements of the storage room

Basically, the wood pellet storage room should be elongated rectangular, with a room width - if possible - no more than 2.0 m:

i.e. W: 2 m x 3 m or 1,8 m x 3,2 m etc.

The narrower the room, the less unused empty space. The size of the required storage room depends on the building heat demand. The following rule of thumb may be applied:

per 1 kW heating load = 0,9 m³ Storage room (including unused empty space)

For example:

One family house with a heat load of 10 kW = 4.000 kg wood pellet annual requirement

The equipement of the tank- and storage room

Ventilation:

Every pellet storage room or installation room for finished storage must be ventilated. The ventilation openings should be designed so that they do not open directly under windows or supply air openings. Ventilation can be provided either via ventilated filling couplings or separate ventilation openings.

Perimeter walls:

The surrounding walls and the ceiling of the pellet storage room and the boiler room should correspond to fire resistance class F 90. The enclosure walls must withstand the static requirements of the weight load of the pellets (weight load 650 kg/m³ aprox.). The storage room walls and their anchorage in the surrounding brick wall should be properly and professionally designed according to the rules of practice. Ceilings and walls are to be designed such that it does not come, through abrasion or delamination, to a contamination of the pellets.

Fire prevention

According to the firing regulations of the federal states, fire protection regulations apply in most states for storage quantities over 10 m³ (approx. 6.5 t) and for pellet boilers with an output of 50 kW or more. Your ÖkoFEN consultant will be happy to provide you with information on fire protection regulations.

Doors:

As with all other heating systems, the boiler room and the storage room doors must be fired proof (at least T 30). They must open outwards and fitted with a seal.
The pellet storage room door shall be provided -inside of the door opening- with wooden planks, so that the pellets do not press against the door.

Sloping floor:

In order to empty the pellet storage room, it is necessary to install an sloping floor in the storage room. ÖkoFEN offer angle brackets to facilitate the construction of the sloping floor structure.

Light wells:

The light wells should be meticulously planned when planning the wood pellet storage room.
You can download auxiliary sketches to help you with the planning.

Filler coupling with closing lid:

The pellets are blown directly into the storage room and the discharged air is evacuated. This requires two "filler couplings" with a lid. (1 x blow + 1 x evacuate)

These couplings including extension pipes, curve pieps and other accessories, are supplied by ÖkoFEN together with the heating system. A wall opening with a diameter of 125 to 150 mm must be prepared on site. It is recommended to use a PVC pipe with a diameter of 125 to 150 mm fixed to the brickwork. The filling couplings are then foamed in the prepared openings. The filler couplings must be connected to the brickwork (grounding).