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Spira condensing wood pellet boiler

5 Year guarantee*

Spira condensing wood pellet boiler

The Grant Spira condensing wood pellet boiler combines easy installation with straightforward operation and low maintenance. Awarded Best Renewable Energy Product 2011 by the SEAI, the Spira utilises our exclusive turbulator baffle system, providing highly efficient, environmentally friendly heating.

It has a rapid ignition system with modulating burner so can operate in much the same manner as a standard oil or gas appliance giving a greater degree of control over your energy usage. Grant biomass boilers have unique built in self-cleaning heat exchangers, along with an automated fuel feed so intervention is kept to a minimum. During the burning of any fuel any water content must be evaporated prior to combustion, this requires additional energy.  Grant biomass boilers use one of the most efficient forms of off gas fuel – wooden pellets.  Compared with logs and wood chips these have a very low moisture content, which helps with combustion efficiency and therefore reduces energy consumption.

a+ Heating

Features & benefits

The Spira range was the first condensing biomass boiler in the UK to be eligible for the Renewable Heat Incentive Scheme. 

The Spira is suitable for homes of all sizes and is a safe, cost effective and convenient way to heat any rural home, but one thing to consider is the amount of space required.  For example, the Grant Spira range can be housed in either a garage or out-house, or you can utilise one of our unique SpiraPod outdoor boiler housings. Knowing exactly where you will be locating the unit at your property is an important consideration before purchasing, especially if you are planning to utilise a bulk pellet store. (read more about siting the Spira below)

Single units are available in outputs of 5-18kW, 6-26kW and 9-36kW. 

The boilers come complete with an adjacent pellet hopper and feed auger, which automatically supplies the Spira with fuel. There is also the option of increasing the output by utilising two boilers (separately flued) and a central hopper/twin auger arrangement. Models include 11-44kW, 12-52kW, 15-62kW and 18-72kW. Using two boilers to achieve higher outputs is very cost effective. When the units are combined their precise electronic burner controls allow both units to modulate as one, down to just 25% of maximum load when the full output is not required. This, combined with the extremely high condensing efficiencies achieved, makes the Spira a unique option when considering a biomass boiler.

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How the Spira works

On start up, the auger feeds the wood pellets into the burner where they are 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 boiler’s primary heat exchanger. The heat energy is then transferred to the water circulating around the radiators/underfloor pipework of the heating system.

It is important to note that in most 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. Grant wood pellet boilers have a unique secondary condensing heat exchanger which has been designed to capture some of this lost latest heat energy so it can maintain extremely high efficiencies.

Siting of appliance

Wood pellet boilers must be installed in damp free environments. The Grant Spira is designed to be sited in a garage, store of outhouse (unless fitted within the Grant SpiraPod which is an outdoor boiler housing for the Spira allowing for external installations).

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. The boilers will carry out an automatic cleaning cycle at pre-set intervals and this process will result in a temporary increase in the noise level so this should be considered when choosing a suitable location. Bulk storage hoppers will require vehicle access for refilling so it is also important to consider where the boiler and its accompanying hopper will be located before purchasing.

Boiler Maintenance

A unique feature of the Grant Condensing Wood Pellet boiler range is that our patented technology results in the boiler requiring very little maintenance compared with other wood pellet appliances. Grant biomass 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 low ash content minimises boiler maintenance as larger amounts of pellets can be burned before the ash pan requires emptying which can be up to 2 tonnes in some instances.

Fuel Storage

It is important to ensure that you have sufficient space to store the wood pellet fuel. A bulk storage system can be employed for greater pellet capacity (eg. 4 tonne store) and this be fed directly into the integral boiler hopper supplied as standard with the boiler. Access to larger stores should also be considered to allow for bulk delivery lorries to deliver. It is also worth ascertaining you pellet supplier’s minimum delivery quantity before selecting a store as this could help determine which size store is most appropriate.

  • *5 year guarantee when installed by a G1 installer. Subject to T&C's
  • Award winning condensing heat exchanger
  • DEFRA approved under the Clean Air Act
  • Automatic pellet feed and ignition
  • Self-cleaning heat exchangers and brazier
  • Integrated pellet store
  • Modulating burner
  • Flue box with integral fan/draught stabiliser
  • Pellet vacuum systems also available/ Can also be fed from a bulk pellet store
What is a biomass boiler?

What is a biomass boiler?

Biomass boilers are fully automatic appliances, behaving more like an oil or gas boiler, and use 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.

Unlike fossil fuels which are a depleting resource, biomass fuel can be sourced from a “closed carbon cycle” system, where the amount of carbon emitted during the burning of fuel is balanced by the planting of trees.  This environmentally friendly way of harvesting fuel to heat your home, therefore cancels out the harmful effects of  carbon being released into our atmosphere.  Trees need carbon dioxide to grow so it is good partnership, one which is environmentally friendly.

The term biomass refers to a type of fuel sourced from living/non living plant matter, which could be in the form of either wooden logs, wood pellets or chips – wood pellets being the most energy efficient.  Our condensing biomass boilers use wood pellets.

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Product code
NOx Emissions
Energy Rating
Load Profile
Energy Label
Product Fiche
WPS518(LH/RH)110 Grant Spira 18kW wood pellet boiler c/w 110kg single hopper and feed auger 273kg 1535mm 1029mm 1029mm - - a+ Heating - View View
WPS518(LH/RH)200 Grant Spira 18kW wood pellet boiler c/w 200kg single hopper and feed auger 308.5kg 1535mm 1129mm 1129mm - - a+ Heating - View View
WPS626(LH/RH)110 Grant Spira 26kW wood pellet boiler c/w 110kg single hopper and feed auger 273kg 1535mm 1029mm 1029mm - - a+ Heating - View View
WPS626(LH/RH)200 Grant Spira 26kW wood pellet boiler c/w 200kg single hopper and feed auger 273kg 1535mm 1029mm 1029mm - - a+ Heating - View View
WPS936(LH/RH)110 Grant Spira 36kW wood pellet boiler c/w 110kg single hopper and feed auger 303kg 1535mm 1029mm 1029mm - - a+ Heating - View View
WPS936(LH/RH)200 Grant Spira 36kW wood pellet boiler c/w 200kg single hopper and feed auger 338.5kg 1535mm 1129mm 1129mm - - a+ Heating - View View
WPS12/52 Grant Spira 2 x 26kW wood pellet boilers c/w 140kg dual hopper and feed augers 505kg 1535mm 1792mm 1792mm - - a+ Heating - View View
WPS15/62 Grant Spira 26kW & 36kW wood pellet boilers c/w 140kg dual hopper and feed augers 535kg 1535mm 1792mm 1792mm - - a+ Heating - - View
WPS18/72 Grant Spira 2 x 36kW wood pellet boilers c/w 140kg dual hopper and feed augers 565kg 1535mm 1792mm 1792mm - - a+ Heating - View View


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