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Condensing Wood Pellet Boilers

Grant biomass boiler rangeWood pellet boilers are an environmentally friendly, safe and convenient way of heating the home, using wood pellets as fuel.

Apart from the green aspect, the units are fully automatic and behave more like an oil or gas boiler, using advanced controls which cleverly regulate the amount of fuel being delivered to the burner to match the heat demand on the boiler. The fuel is fed to the burner via an auger connected to the adjacent pellet store/hopper. This can, in turn, be automatically supplied from a bulk pellet store which can vary in size.

The process of burning wood produces ash, so wood pellet boilers, biomass boilers  normally require a certain amount of regular cleaning and maintenance, which can be tedious. Grant has, however, has a better solution with a unique ‘self cleaning’ boiler design, reducing the need for cleaning to once a year under normal running conditions.

How a Grant wood pellet boiler works

On start up the auger feeds the wood pellets from the hopper into the burner where it is lit by an ignition element. The burner output modulates to achieve the set temperature by controlling the feed rate of pellets. The fan in the burner propels hot gas generated from the fuel into the Spira’s primary heat exchanger. The heat energy is then transferred to water from the central heating system, before being circulated around house to radiators/underfloor. It is important to note that in modern pellet boilers, up to 20% of the energy that is produced is lost to the atmosphere through waste gases exhausted by the flue system, The Spira has a unique secondary condensing heat exchanger which has been designed to capture some of this lost latent heat energy, so it can maintain extremely high efficiencies. The boiler’s fully automatic cleaning system will periodically wash the condensing unit of any debris in the tubes and also activate the brazier within the burner to clear the combustion chamber of ash build up, which reduces maintenance time.

Grant Approved Installers

Grant wood pellet boilers must only be fitted and commissioned by a heating installer who has been fully trained and approved by Grant under the G-One Scheme.  Failure to comply with this may result in the product guarantee becoming invalid.

Unique and efficient boilers

The MCS approved Grant Spira condensing wood pellet boiler utilises the award winning patented stainless steel Vortex turbulator baffle system and has many benefits including:

  • Rapid ignition with modulating burner. This means our boilers operate in much the same manner as a standard gas boiler to give you a greater degree of control of your energy output and control.
  • Require little intervention. Grant are proud to have a unique self-cleaning design and automated fuel feed so the need for you to intervene is kept to a minimum.
  • Lower energy consumption and greater efficiency. Biomass fuel is slightly more cost effective than fossil fuels.  Due to the extreme efficiency of our boilers (up to 97%) thanks to our award winning patented baffle system, we are able to provide you with some of the most efficient boilers on the market.
  • Suitable for home use. Grant wood pellet boilers are a safe and convenient way to heat your home.  One thing to consider is the amount of space you may require for the boiler and pellet hopper/store.  Unlike traditional solid fuel appliances, the boilers use an automatic feed for the wood pellets, which means less hassle for you.

Siting the appliance

Wood pellet boilers must be installed in a damp free environment. The Grant Spira is designed to be sited in a garage, store or outhouse, while the smaller size and stylish white casing makes the Grant Vecta ideal for a utility room.

To enable the boiler to operate safely and efficiently, a correctly sized and permanently open air vent (open to the outside) should be provided in the boiler room. It is also important to bear in mind that the boilers will carry out a sporadic cleaning cycle. This process will result in a temporary increase in noise level, so should also be considered when choosing a suitable location.

Storage hoppers will require vehicle access for refilling, making it is important to consider where the boiler and its accompanying hopper will be located before purchasing.

Grant Spira Condensing Wood Pellet boilerLooking after your pellet boiler

A unique feature of the Grant Condensing Wood Pellet range is that our patented technology results in the boiler requiring very little maintenance compared with other wood pellet appliances.

Our boilers have an automatic self-cleaning system for the primary and secondary heat exchangers to ensure they stay free of debris. They also feature a self-cleaning burner.

Using a Grant approved EN Plus Grade A1 wood pellet with a low ash content minimises boiler maintenance, as larger amounts of pellets can be burned before the ash pan requires emptying – up to 2 tonnes in some instances.


Grant wood pellet boilers are guaranteed for one year from date of purchase, two years if the product is registered within 30 days (excluding consumable items) and 5 years if installed by a G-One engineer (subject to being serviced annually and installed in accordance with the manufacturer’s instructions).

Grant Vecta Condensing Wood Pellet boiler handoverIn the unlikely event of a problem occurring, you must first contact your G-One installer to attend the fault. If it cannot be rectified, they should telephone the Grant Customer Service Department on: 01380 736920. 




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