Knowledge Hub


Air Source Heat Pumps

What is a heat pump?
A heat pump uses the principles of thermodynamics to absorb energy from the surrounding environment and convert into usable energy and provide heating for our homes. There are a variety of heat pump products available - The Grant Aerona range features Air Source Heat Pumps (ASHP).
How do air source heat pumps work?
There are two types of air source heat pump – ‘air to air’ and ‘air to water’. The Grant Aerona uses an air to water system which utilises heat energy captured from the air in ‘wet’ heating system radiators or underfloor heating. The process uses the same vapour/compression cycle that extracts heat in a domestic fridge. A refrigerant with a low boiling point is exposed to external air temperatures in an evaporator. The liquid boils off to a gas and absorbs the latent heat energy of the air. This gas is then compressed increasing the heat content in the refrigerant, before passing through a heat exchanger where it condenses back to a liquid state while transferring the heat to the water of the heating system. The liquid refrigerant is then re-circulated through the evaporator and the cycle is repeated.
Is an air source heat pump good for the environment?
Yes, the heat source used by Grant Aerona heat pumps is entirely renewable which helps reduce the amount of harmful greenhouse gases being released into the atmosphere and, in so doing, lowers the carbon footprint of the household.
What space do I require for an air source heat pump?
An air source heat pump needs to be located outside in the open air and sufficient space must be allowed around the unit (1000mm from front and sides, 300mm from back) so air can flow freely into it. The unit also needs to be installed on a flat trowelled finished concrete base 150mm thick and this base should extend at least 100mm beyond the unit on three sides. Full details are given in the Installation and Servicing instructions supplied with any Grant Aerona air source heat pump.
Where should I site an air source heat pump?
The north face of a building will usually have colder ambient air than any other side so, to ensure maximum efficiency from a Grant Aerona heat pump, position the unit on a warmer side, preferably south facing. All heat pumps make a noise so take opening windows and doors into account when considering the final position.
What is R32 refridgerant and what is the benefit?
Grant’s latest ASHP uses R32 refrigerant which has a GWP which is considerably lower than other typical heat pump refrigerants such as R410, thus complying with the upcoming legislative targets. In addition to having a lower GWP figure of 675, R32 is a single-component refrigerant which means it has no temperature glide. Refrigerant blends that have two or more components exhibit temperature glide but as R32 only has one molecule in its formation, its saturated liquid and vapor temperatures are the same. By removing the risk for the refrigerant to suffer from glide, the system can recharge and recycle with greater ease, making it more efficient.
Do I need planning permission?
You should check with your Local Authority Planning Department prior to any work commencing, as in some cases planning permission may be required for the installation of a heat pump.
Why is it important to size a heat pump correctly?
Air source heat pumps must be correctly sized to ensure that it can provide the required amount of heat output at the design conditions – typically when the outside temperature is at -3°C. To do this an installer must first accurately determine the heat loss from the property and then, using this information, correctly select the required size of heat pump based on the design outside air temperature. Grant can assist with sizing the ASHP and the heat loss of the building.
How do air source heat pumps operate in very cold weather conditions?

During winter months when it is particularly cold, condensation can form and freeze on the finned evaporator coil of the unit. It is a normal occurrence and the heat pump is designed to cope with this. The control system will detect when the coil has iced up and will automatically enter a ‘defrost’ cycle. During this short ‘defrost’ period the fan will stop and the heat pump will cease supplying heat to the heating system in order to melt the ice. On completion the fan and heat pump will automatically restart and resume supplying heat to the heating system. This will not adversely affect the building temperature.

Is an air source heat pump noisy?

Heat pumps use either one or two fans to draw air through the unit to extract the heat energy. These fans will produce a moderate sound level that might be perceived by some as a nuisance, either by the occupants of the building with the heat pump system, or the neighbours. In particular this may be a greater problem at night when background noise is much lower. Careful choice of the heat pump location can help to minimise or eliminate the potential nuisance, e.g. not too close to bedroom windows (particularly with a bungalow) or too close to a neighbour’s boundary or property. Two of our latest models, the Aerona³ R32 13kW and 17kW heat pumps have achieved the Quiet Mark, an accolade which recognises some of the quietest, high performing products in the market.

Will my electricity bills increase?
With no beating around the bush, yes your household electricity consumption will increase using an air source heat pump. However there will usually be NO gas or oil bill to pay to heat the house, unless a bivalent heating system is chosen (combining the heat pump with a gas or oil-fired boiler as a backup heat source). You should therefore consider the overall cost of heating, i.e. the increased electricity cost compared with the saving in oil or gas bills.
Should I change my electricity tariff?
Where electricity is the only energy source used, a change to the electricity tariff might be possible enabling the heat pump to run more economically. It is always worth enquiring with your energy provider, as depending upon your electricity demand, they may have a plan that is more suitable e.g. Economy 10.
Are Grant air source heat pumps MCS approved?
Yes, all models within the Grant Aerona range are MCS approved.
What type of heating system controls are used with Grant heat pumps?
Normal domestic heating controls, such as a 2-channel programmer, room thermostat and cylinder thermostat.
How often should a Grant heat pump be serviced?
Grant heat pumps should be serviced annually. Failure to do so will invalidate the product guarantee.
Is it possible to use radiators with a heat pump?
Yes, but they must be correctly sized for the lower water flow temperature.
Can a heat pump be connected to an existing hot water cylinder?

The coil of an existing cylinder will almost certainly be too small and this will result in longer cylinder reheat times at the lower water flow temperatures from a heat pump. For best performance a Grant High Performance cylinder should be used. This has a larger coil to reduce reheat times.

I live near the coast, is there anything I need to do differently?
If a Grant Aerona³ R32 air source heat pump is installed within the vicinity of the coast (up to two miles), the evaporator will need to be sprayed with ACF50 during the installation and then this must be repeated at each annual service. Alternatively, Grant offer Blygold anti-corrosion treatment for all of their Aerona³ R32 heat pump models which is designed to preserve the heat pump against the sea air.
What is Blygold treatment?
Blygold anti-corrosion treatment is designed to preserve the heat pump against the sea air and prevent unnecessary energy consumption or product failure due to corrosion. Grant offer Blygold anti-corrosion treatment for all of their Aerona³ R32 heat pump models to help preserve and maintain heat pumps installed in the vicinity of the sea. For further information, speak to our sales team on 01380 736920

Underfloor Heating

Can only new builds have underfloor heating?
Underfloor heating is not restricted to new build properties, it can be also be installed as a retrofit project into many older properties.
Is UFH restricted to the ground floor?
No. UFH can be installed both upstairs and downstairs in a property. Speak to our renewables team for specifications.
How long does installation of an UFH system take?

Grant's underfloor heating systems include, Uflex and Uflex MINI. With a drying time of thirty days, the Uflex underfloor system is best suited to the new build and renovation market, this is so the underfloor system can be fitted as part of the floor construction process. Uflex MINI however has a drying time of 3 days. It is suitable for both new builds, as well as retrofits and renovations, when an underfloor heating system is to be fitted in a property with a floor construction already in place. At just 15mm in height, this underfloor system can be installed incredibly quickly and with minimal disruption to a property’s existing floor and door arrangements.

Can the system be added to my existing heating system?
UFH is suitable for gas, oil, and LPG boilers as well as heat pumps and biomass boilers. For more information, speak to our Renewables Team.
Do I need to dig up the floors?

No! The Uflex MINI system is specifically designed to suit retrofits and renovations, when an underfloor heating system is to be fitted in a property with a floor construction already in place. At just 15mm in height, this underfloor system can be installed incredibly quickly and with minimal disruption to a property’s existing floor and door arrangements.

Does underfloor heating work the same way as a radiator?
Radiators rely on air circulation to enable the hot air to move around the room, this is called thermal currents and involves the hot air moving from the radiator to the ceiling, cooling and falling to create an air cycle. This can leave colder areas and takes time to heat the room. An underfloor heating system heats the room by hot air rising from the floor surface upwards, this uses considerably less energy and also creates a more even dispersion of heat.
I have carpets. Will this stop the Underfloor heating from working?
Not all types of floor finishes are compatible with underfloor heating systems. The objective of underfloor heating is to transfer heat from the system into the room and some floor coverings can restrict this movement of heat. Flooring materials such as tiles and vinyl floor coverings are low resistance and are therefore ideal for underfloor. Meanwhile, thicker finishes such as certain types of wood and thin carpets have medium resistance which means that some of the heat is retained. Any carpets and overlay which are over 2.5tog are not suitable for an underfloor heating system.
Is underfloor cheaper to run than traditional heat emitters?
Yes, data suggests that underfloor heating can be 25% cheaper to run than radiators when used in conjunction with a condensing boiler and up to 40% cheaper to run when used with a heat pump, (EuRay 2005.)
What is zone control?
A zone is an area or a room that is controlled independently via a room thermostat. A house could be split into two zones for example upstairs and downstairs or each room could be classed as a separate zone. Zone control gives you greater control over your heating and ensures each area is at optimum temperature.
What is overboarding and do I need it?
Overboarding involves the fitting of an overlay or base layer in between the screed and the floor finish. Some types of underfloor systems, such as electric UFH, require a form of overboarding to be fitted as standard. However, Grant’s Uflex underfloor system does not need overboarding which allows installers to lay the final floor covering directly on top of the dry screed.
What is a manifold?
The manifold is the system hub for the underfloor, the pipes are connected to it at installation stage and it then controls the distribution of the water from the heating systems source (boiler/heat pump) throughout the underfloor system. It is at the manifold that the control of the flow to each individual zone or room is achieved.
Where should a manifold be situated?
The manifold should be located in a central point where the pipework is most evenly distributed.
Its recommended I keep my underfloor system running constantly, why is this?
Grant's underfloor heating systems operate at their most efficient when they are not frequently switched off and on. The floor screed takes time to heat up, but once up to temperature it only requires a small amount of heat to maintain this condition. Switching the system off and on, results in the floor losing temperature, requiring more heat input to reach temperature again.
Can I fit underfloor heating under a kitchen unit?
Yes, providing there are no fixings that may damage the pipe, we advise to lay the underfloor across the total floor area as the future layout could be different. We do not recommend the underfloor to be fitted below sanitary items as these are often fixed to the floor and could damage the pipes.
What are setback controls?
Operating the system with a 'setback' control, maintains the floor at a minimum temperature at all times and avoids the wasteful use of energy to continually reheat the floor from cold.

Hybrid Heating

What is a Grant VortexAir Hybrid?
It is a combination of a high efficiency condensing blue flame oil boiler and an air source heat pump, interconnected using a control system, such that they operate together as a single unit.
How does a hybrid system work?
The control system on the hybrid unit monitors the ambient (outside) air temperature and allows only the heat pump to operate when the air temperature is high enough for it to meet the heat demand of the building on its own. At lower ambient air temperatures the boiler will operate alongside the heat pump, providing a boost to the flow temperature. When the ambient air temperature falls lower still, the boiler is operated at its full output at a higher flow temperature to enable the hybrid unit to meet the higher heating demand of the building.
What is the benefit of using a hybrid?
A hybrid unit enables the optimum use of both an inverter driven air source heat pump and a blue flame condensing oil boiler, throughout the year, as the ambient air temperature (and consequently the heat demand of the building) changes, thus providing the most efficient use of both the renewable and non-renewable energy sources.
What is the benefit of using a hybrid over using a heat pump only?
Heating system radiators in existing properties are usually sized using the higher water flow temperatures produced from a boiler and so, to meet the same heat demand using the lower flow temperatures produced by a heat pump, the radiators would normally need to be increased in size. Using a hybrid unit combines the higher flow temperatures produced by a boiler, with the efficient operation of a heat pump, to meet the buildings heat demand throughout the year. When the weather is warmer, i.e. in the spring and autumn, the heat pump works independently and the existing radiators can meet the heat demand with the lower flow temperature. This allows the very efficient use of electrical energy to drive the heat pump for large periods of the heating season. When the weather gets colder, the boiler operates to provide the additional energy required negating the need to increase radiator sizes.
How is the Grant VortexAir Hybrid connected to the heating system?
The boiler is always fitted first and the heating system in the building is connected directly to it, whether or not it is located outside next to the heat pump or indoors. The heat pump is then installed and also connected directly to the boiler.
Where should the Grant VortexAir Hybrid be located?
The VortexAir is designed to be installed outdoors, i.e. both the boiler and heat pump parts are located next to each other outside the building. However, it is also possible for the boiler part to be installed internally with the heat pump still outside. Full details for both types of installation are given in the installation instructions supplied with the unit.
Do both the oil boiler and heat pump parts have to be installed at the same time?
No. The boiler can be installed and, if necessary, operated as a stand-alone unit for an indefinite period until the heat pump can be installed and connected to it. This is particularly useful when an existing boiler has to be replaced in an emergency due to a breakdown. The installation of the heat pump can follow at a later date when convenient.
What are the benefits of the blue flame burner technology used in the Grant VortexAir Hybrid?
The boiler used in the Grant VortexAir Hybrid is the latest in a family of high efficiency condensing oil boilers. Whilst maintaining the current high level of efficiency, the use of blue flame technology reduces emissions. In particular, the NOx level in the flue gases, such that the boilers will meet new emissions limits to be introduced in September 2018.
Does the blue flame burner have any special servicing requirements?
No. The blue flame burner and boiler is serviced in exactly the same way as any other boiler from the award winning Grant high efficiency Vortex condensing range. The boiler is accessed via a removable door on the right hand end of the casing and most of the electrical servicing can be easily done from the front of the appliance.
What type of flue system is used for the oil boiler part of the Grant VortexAir Hybrid?
The VortexAir Hybrid uses the Grant low level balanced flue system (or Yellow system) irrespective of whether the boiler part is located inside or outside the building. In the case of it being located indoors, the flue system exits at the rear of the unit and passes through the external wall of the building. If the boiler is outside it is fitted through the right hand side of the unit, above the boiler access door. The hybrid unit must be located such that the flue terminal clearance requirements of BS5410-1:2014 are complied with.
What type of oil is used for the boiler of the Grant VortexAir Hybrid?
As with Grant Vortex boilers, the VortexAir Hybrid is only suitable for use with standard kerosene (Class C2 to BS2869). Gas oil (Class D to BS2869) must not be used with the hybrid boiler.
Does the Grant VortexAir Hybrid qualify for a Government RHI?
To qualify for an RHI (or Renewable Heat Incentive) payment, the unit must be MCS approved and both of the Grant VortexAir Hybrid models meet this requirement. Furthermore, the unit must be installed by an MCS approved Installer and fitted with both a heat meter and electricity meter in accordance with MCS requirements for the RHI. However, it should be understood that using both an MCS approved product and installer is not a guarantee that the installation will be eligible for an RHI payment.
Does the VortexAir come fitted with a heat meter?
No. As not all installations will require a heat meter and electricity meter, the Grant VortexAir Hybrid is supplied without any meters fitted. Usually only installations qualifying to receive an RHI payment will require both of these meters to be fitted. However, in accordance with MCS metering requirements, the Grant VortexAir Hybrid is supplied ‘meter ready’ to allow both the heat meter and electricity meter to be easily fitted if required. The heat meter and electricity meter are available as accessories from Grant.
Who can install the Grant VortexAir Hybrid?
Installation of the hybrid unit requires an installer who is both competent in the installation of oil fired boilers (preferably a registered oil installer, e.g. OFTEC registered or similar) and also able to install an air source heat pump. Grant strongly recommends that any installer intending to fit a VortexAir Hybrid should first attend a Grant training course. If an RHI payment is required, the installer will have to be MCS accredited for the installation of air source heat pumps.
Is Planning Permission required?
Usually, compliance with the Town and Country Planning legislation for England, and the MCS Planning Standards, for permitted development means that Planning Permission is not usually required to install a Grant VortexAir Hybrid. However, this should be checked with the Local Authority Planning Department in all cases. It is the responsibility of the householder to undertake this check.
What would the cost benefits be of installing a Grant VortexAir Hybrid?
This is a complicated question to answer. Any cost benefit is dependent on a variety of different factors, including the heat demand of the property, the type of heating system currently installed, the pattern of heating usage, the cost of both electricity and heating oil at the time of installation, etc. Consequently, cost benefits will vary from one installation to another.
Are Grant ASHPs eligible for the RHI?
To qualify for an RHI payment, the unit must be MCS approved. The Grant Aerona meets this requirement. Furthermore, the heat pump must be installed by an MCS approved Installer. However, it should be understood that using both an MCS approved product and installer is not a guarantee that the installation will be eligible for an RHI payment.

Solar Thermal Systems

What is the difference between solar thermal and Solar PV?
A Solar PV system uses panels (usually called ‘modules’) that generate electricity in the presence of sunlight. The amount of electricity produced depends on the intensity of the sunlight. Solar thermal, on the other hand, uses sunlight to heat a fluid. In the case of Grant solar collectors, it heats a glycol/water solution within the collector. This heated fluid is then circulated from the collector to a cylinder where the heat is transferred to produce hot water.
Who can install Grant Solar Thermal?
The installation of the Grant Solar Thermal system must be carried out by a competent trained person in accordance with the relevant requirements for health and safety, local building regulations, building standards in Scotland and regulations and bylaws of the local water company.
Is planning permission required for Solar Thermal panels?
Recent changes to legislation mean that planning permission is not required on most domestic houses, unless the property is listed, or in an area of outstanding natural beauty. Please note that Regulations are subject to change, so for more in depth information and advice, please contact your Local Authority or visit the Energy Savings Trust website (hyperlink to EST).
Will the solar panels still work on a cloudy day?
Many people believe that solar collectors only work in the summer, however this type of free energy is available throughout the year. From May to September, solar thermal could produce 100% of the energy required for heating your domestic water. Grant collectors operate not just with direct sunlight, but also diffused sunlight, so they even work on cloudy days.
Does it matter what direction the Solar Thermal collectors are facing?
For installations in the UK, Solar Thermal collectors will perform best when facing due south at an angle of between 30 - 45°. However, collectors facing south west or south east will perform almost as well. Failing that a collectors facing due west will perform better than those facing due east. North facing Solar Thermal collectors are not usually used.
Can solar thermal collectors be mounted on any type of roof?
Grant solar thermal collectors can be fitted on many different types of roof, both flat and pitched. Collectors can be mounted either just above the roof covering or set into the roof, as required.
Do solar thermal systems require a lot of maintenance?
No. Grant Solar Thermal systems require only basic maintenance in order to ensure that they continue to give trouble free operation.
Can solar thermal be used to heat my house?
Whilst solar thermal can be used to contribute to the heating of a house using a thermal store, it is more usually used to simply heat your domestic hot water cylinder
Can a solar thermal system be used with my existing hot water cylinder?
A Grant solar thermal system requires a cylinder with a solar coil. In many cases this will be a ‘twin coil’ cylinder with both a boiler coil and a solar coil. This may well mean that your existing hot water cylinder will have to be replaced by a suitably sized twin coil cylinder to maximise the performance of your Solar Thermal system.
Can solar thermal be used to heat a swimming pool?
Yes. Solar Thermal collectors can be used to provide heat for a swimming pool.
Could the collectors of a Grant Solar Thermal system freeze up in cold weather?
No. The solar fluid used in a Grant solar thermal system is a 40% propylene glycol solution. This provides frost protection for the collectors and external pipework down to -25°C.
Are Grant Solar Thermal Systems eligible for the RHI?
To qualify for an RHI payment, the solar thermal collectors must have MCS certification or an equivalent approval such as Solar Keymark. Grant Solar Thermal collectors have the Solar Keymark, so meet this requirement. Furthermore, the entire solar thermal system must be installed by an MCS approved Installer. However, it should be understood that using both an approved product and installer is not a guarantee that the installation will be eligible for an RHI payment.

Fan Convectors

What heat sources are fan convectors compatible with?
Fan convectors are designed to be integrated into low temperature heating systems using air source heat pumps, condensing oil, gas and biomass boilers, etc.
Why are fan convectors good for use with heat pumps?
Fan convectors heat up faster than conventional radiators as they require no warm up time and can start distributing heat as soon as hot water is available, they also enable a constant flow to be sustained through the system which greatly assists the correct operation of heat pumps. The two technologies are designed to work together to deliver improved efficiencies throughout the entire heating system.
Why are fan convectors said to be safer?
While the Solo fan convectors are designed to emit heat quickly, their surface temperature never reaches dangerous levels regardless of the water temperature which makes these units safer to touch especially for children and the elderly.
How would I set/control the fan convector temperature?
The user can set the required room air temperature between 18 to 24°C via the control panel on the front of the unit. To set the required air temperature Press the ON/OFF button momentarily – the lowest (single bar) indicator light will flash slowly indicating that the air temperature setting is 18°C. To increase the setting Press the ON/OFF button again momentarily – the next (two bars) indicator light will now flash slowly indicating that the air temperature setting is now 20°C. To increase the temperature futher, continue this until maximum temperature of 24°C is reached (4 bars) Pressing the ON/OFF button again momentarily will return the air temperature setting to the minimum (18°C) and the left hand (single bar) indicator light will now flash slowly.

Biomass Boilers

What is a wood pellet boiler?
Wood pellet boilers are a safe, convenient and environmentally friendly way of using wood to heat your home. Grant wood pellet boilers are fully automatic and perform more like an oil or gas boiler, using advanced controls which regulate the amount of fuel being delivered to the burner to match a home’s heat demand. Wood pellets are fed into the burner via an ‘auger’ connected to a storage hopper.
How do wood pellet boilers work?
The boiler auger feeds wood pellets directly into the burner where they are ignited, and the heat generated is automatically controlled by the feed rate of pellets. A fan in the boiler propels hot gas into the boiler primary heat exchanger. The heat energy is then transferred to the central heating system before being circulated around the house through either radiators and/or underfloor heating.
How are wood pellets made?
Wood pellets are made from compressed sawdust fused together by the natural lignin present in dry wood. A low moisture content (less than 10%) is important to help increase the combustion efficiency of the fuel - the drier the pellet, the more efficient the boiler. Because the sawdust used to make wood pellets is either a bi-product of the timber industry (i.e. sawmills) or has been sourced from a managed forest where trees are planted to replace the ones cut down, they are classed as a sustainable or ‘carbon neutral’ source of fuel.
Can I burn wood chip or logs in a Grant Biomass boiler?
No. Grant biomass boilers use wood pellets only.
Are there waste products from a wood pellet boiler?
As part of the normal operating process wood pellet boilers produce ash as a waste product. This means that the boiler will require regular cleaning by the user and periodic maintenance by the installer or Grant approved service engineer. The ash that is produced by the boiler can be scattered on the garden once it has cooled to add essential plant nutrients to your soil.
What are the benefits of choosing a Grant wood pellet boiler?
Greener heating - Wood pellets are an environmentally-friendly fuel produced from either recycled saw dust or virgin timber from managed resources. The carbon dioxide emitted when wood is burned is the same amount that was absorbed over the months and years that the plant was growing making this a very green way to heat your home. Easy to clean and maintain - Wood pellet boilers produce ash and can normally require frequent cleaning and maintenance by the user. The Grant Spira boilers operate a self-cleaning function, reducing the need for regular cleaning when using EN Plus A1 grade pellets with low ash content. Reliability - All Grant wood pellet boilers feature our award winning heat exchangers so you get the guarantee of reliability and quality which has become synonymous with the Grant name. We are so confident in the Spira’s reliability that we offer a 2 year parts and labour product guarantee on all new models (5 years when installed by a Grant approved G1 registered installer).
Is my existing heating system compatible?
Grant wood pellet boilers can be used with any 2-pipe, fully pumped hot water heating system – either open-vented or sealed - using radiators and/or underfloor heating. Wood pellet boilers can be fitted as a replacement boiler on an existing heating system (providing that the system has been chemically cleaned and flushed and complies with Building Regulations) and the existing control system may also be used (providing it also complies with these regulations).
What space do I require for a pellet store?
Pellets can be fed manually into the boiler hopper, but a more convenient alternative is to install a bulk storage unit (e.g. 3 tonnes) to store and deliver the pellets automatically to the hopper. While an external bulk storage system allows for increased pellet capacity, it is important to ensure you have sufficient external space for the store. Typical sizes are approximately 4m2 in size but you will also need to have clear access for the large lorries to deliver the pellets to the store. Full details are given in the Installation and servicing instructions supplied with any Grant boiler.
Where do I install a Grant wood pellet boiler?
Pellet boilers must be installed in a damp free environment along with the accompanying pellet hopper. Traditionally, due to space and noise considerations wood pellet boilers have needed to be situated in an outbuilding or garage. The Grant Vecta Internal however, with its quiet operation and compact casing design, makes installation within a kitchen or utility environment ideal. The latest Grant Vecta External wood pellet boiler has been designed to be sited externally, saving valuable space inside the home.
Where can I buy the wood pellets?
Wood pellets can be purchased from a variety of manufacturers and specialist suppliers with some larger plumbing and heating merchants now stocking pellets. Pellets are available either in bags (usually 10kg bags or 15kg quantities) or in bulk, delivered by lorry direct to your home. The minimum bulk pellet delivery is typically 3 tonnes but this needs to be checked with the supplier concerned, as smaller deliveries may be possible.
How do I fill a Grant wood pellet boiler?
If you are not planning to purchase a bulk pellet storage unit, the pellet hopper supplied with the boiler will need to be filled manually with pellets supplied in bags. If you are purchasing a bulk pellet store it will automatically feed the boiler hopper. It is important to regularly check the bulk store to ensure that you have sufficient fuel which will allow you to order a bulk delivery before it is empty.
How do the pellets get from the store to the boiler?
Pellet boilers will either use an auger to draw the fuel from the bulk store, or for installations that require the bulk storage to be sited further away due to space restrictions, a vacuum system can be used, transporting the pellets quickly and quietly to the boiler. The Grant SpiraVAC system is capable of lifting pellets up to a height of 3 metres with maximum pipe runs of 20 metres, making the most awkward siting a possibility. It is compatible with Grant Spira models only.
When do I need to refill the hopper/store?
With most indoor systems the boiler will automatically stop when the pellet level in the hopper reaches minimum. To avoid this happening, the pellet level in the hopper should be regularly checked and topped up as required – usually once to twice a week. If a bulk pellet store is used, this will automatically top up the indoor pellet hopper to ensure that the level never reaches minimum. However, the pellet level in the bulk pellet store must be regularly checked and a delivery of pellets ordered in plenty of time before it becomes empty. The time between deliveries will depend on the size of the bulk store, the size of the boiler and how it is used.
Is a wood pellet boiler noisy?
Any noise from a wood pellet boiler comes from the flue fan, the burner fan, the pellets themselves dropping into the burner and (in the case of a Grant pellet boiler) the self-cleaning process. Whilst the combination of these sources is not excessively noisy, some pellet boilers may not be suitable for installation within the ‘habitable’ rooms of a house, which are often used for locating conventional oil and gas boilers. The Grant Vecta, however, has been developed with a compact insulated casing and is designed to fit and work where an existing floor standing oil-fired boiler may originally have been situated.
Does a wood pellet boiler require cleaning and maintenance?
Every pellet boiler requires a degree of regular cleaning and maintenance to ensure they continue to run efficiently, which can be messy and time consuming. The efficient combustion of a Grant Wood Pellet Boiler, coupled with the high quality wood pellets approved for use with Grant appliances, results in a relatively small amount of fine ash being produced. Grant Wood Pellet Boilers also incorporate automatic cleaning at pre-set intervals to remove ash deposits in the primary and condensing heat exchangers as well as the burner brazier. The amount of ash produced can vary depending on the make of pellets and how often the boiler is used. The ash pan on the Spira, for example, should not require emptying any more than once a month. In order to ensure efficient and safe operation, all wood pellet boilers must be serviced annually. In a Grant boiler, the primary and condensing heat exchangers, combustion chamber, flue fan box and burner must be cleaned and the burner re-set either once a year, or when the ‘SERVICE’ message on the control panel is displayed. This service interval is based on the actual running time of the burner and may vary in length depending on the degree of use of the boiler.
Are Grant wood pellet boilers MCS approved?
Yes, all Grant Wood Pellet boilers are MCS approved.
Are Grant wood pellet boilers eligible for the RHI?
To qualify for an RHI payment, the unit must be MCS approved. All Grant wood pellet boilers meet this requirement. Furthermore, the boiler must be installed by an MCS approved Installer. However, it should be understood that using both an MCS approved product and installer is not a guarantee that the installation will be eligible for an RHI payment.
How often should a Grant wood pellet boiler be serviced?
When indicated on the control panel display or after 12 months, whichever comes first.
Is a buffer required for Grant biomass boilers as with some other Biomass appliances?
No. Grant Biomass boilers have modulating burners that regulate the boiler heat output to meet the changing demand from the heating system.


What does an ISO 14001:2015 mean?
ISO 14001:2015 sets out the criteria for an environmental management system and can be certified to. It maps out a framework that a company or organization can follow to set up an effective environmental management system. It can be used by any organization regardless of its activity or sector. Using ISO 14001:2015 can provide assurance to company management and employees as well as external stakeholders that environmental impact is being measured and improved. External audits are completed yearly to ensure the business is maintaining these principles.
What does an ISO 9001:2015 certification mean?
This standard is based on a number of quality management principles including a strong customer focus, the motivation and implication of top management, the process approach and continual improvement. Using ISO 9001:2015 helps ensure that customers get consistent, good quality products and services. External audits are completed yearly to ensure the business is maintaining these principles.
What is Cyber essentials?
In June, Grant UK completed an assessment against the Cyber Essentials Standard which they passed. Having met the requirements of the scheme, Grant UK have been awarded a Certificate of Compliance which acknowledges the strength of the Company’s ICT defence protocols.
I've seen a logo on certain products 'Energy savings Trust Endorsed product', what does this mean?
The Energy Saving Trust endorses energy efficient products that have met industry agreed standards for energy performance. All our oil boilers are endorsed by the Energy Savings Trust.
What benefit is an 'MCS Approved product' to me?

The Microgeneration Certification Scheme is a government driven scheme to promote renewable technologies. It is an internationally recognised quality assurance scheme which demonstrates the quality and reliability of Approved Products by satisfying rigorous and tested standards. MCS is linked to the Governments’s finance schemes and incentives, such as the Feed-in Tariffs (FIT) and the Renewable Heat Incentive (RHI). If you wish to take advantage of these schemes, an MCS approved product must be used. For further information visit

What is a WRAS Approved product?
Any water fitting, which when installed, will carry or receive water from the public mains water supply in the UK, must comply with the Water Supply (Water Fittings) Regulations or Scottish Byelaws. These require that a water fitting should not cause waste, misuse, undue consumption or contamination of the water supply and must be ‘of an appropriate quality and standard’.

Data Protection

What is the GDPR?
The EU General Data Protection Regulation (“GDPR”) comes into force across the European Union on 25th May 2018 and brings with it the most significant changes to data protection law in two decades. Founded on the basis of privacy by design and taking a risk-based approach, the GDPR has been designed to meet the requirements of the digital age. The 21st Century brings with it broader use of technology, new definitions of what constitutes personal data, and a vast increase in cross-border processing. The new Regulation aims to standardise data protection laws and processing across the EU; affording individuals stronger, more consistent rights to access and control their personal information.
How is Grant UK safeguarding my data under the GDPR?
Grant UK is committed to ensuring the security and protection of the personal information that we process, and to provide a compliant and consistent approach to data protection. We have always had a robust and effective data protection program in place which complies with existing law and abides by the data protection principles. However, we recognise the requirement and importance of updating and expanding this program to meet the demands of the GDPR and the UK’s Data Protection Bill. Grant UK is dedicated to safeguarding the personal information under our remit and in developing a data protection regime that is effective, fit for purpose and demonstrates an understanding of, and appreciation for the new Regulation.
What is a Subject Access Request (SAR)?
A Subject Access Request (SAR) is the right of an individual to request any personal data that Grant UK hold on their behalf. This right is a principle of the GDPR, designed to regulate the processing of information from which a natural living person can be identified either from the information itself or when combined with other data. We are committed to upholding the rights of individuals and have dedicated processes in place for providing access to personal information. Where requested, we will provide the following information: - • the purposes of the processing • the categories of personal data concerned • the recipient(s) or categories of recipient(s) to whom the personal data have been or will be disclosed • the envisaged period for which the personal data will be stored (or the criteria used to determine that period) • where the personal data was not collected directly from the individual, any available information as to its source
How can I make a Subject Access Request (SAR)?
A subject access request (SAR) is a request for access to the personal information that the Company holds about you, which we are required to provide under the GDPR (unless an exemption applies). The request doesn't have to specify it's a SAR or refer to the GDPR; it can be a general request for personal information. You can make this request in writing to our registered office address: FAO The Data Protection Manager, (GDPR Governance Group), Grant Engineering (UK) Ltd, Hopton House, Hopton Industrial Estate, Devizes, Wiltshire, SN10 2EU. Or, you can submit your access request electronically by email to Where a request is received by electronic means, we will provide the requested information in a commonly used electronic form (unless otherwise requested by the data subject).
How do Grant UK process a Subject Access Request (SAR)?
Subject Access Requests (SAR) are passed to the Company’s Data Protection Governance Group as soon as received and a record of the request is made. The person in charge (Our Data Protection Manager) will use all reasonable measures to verify the identity of the individual making the access request, especially where the request is made using online services. We will utilise the request information to ensure that we can verify your identity and where we are unable to do so, we may contact you for further information, or ask you to provide evidence of your identity prior to actioning any request. This is to protect your information and rights. If a third party, relative or representative is requesting the information on your behalf, we will verify their authority to act for you and again, may contact you to confirm their identity and gain your authorisation prior to actioning the any request. Information Gathering If you have provided enough information in your SAR to collate the personal information held about you, we will gather all documents relating to you and ensure that the information required is provided in an acceptable format. If we do not have enough information to locate your records, we may contact you for further details. This will be done as soon as possible and within the timeframes set out below. Once we have collated all the personal information held about you, we will send this to you in writing (or in a commonly used electronic form if requested). The information will be in a concise, transparent, intelligible and easily accessible format, using clear and plain language.
Is there a charge for a Subject Access Request (SAR)?
SARs are always completed within 30-days and are provided free of charge. Where the request is made by electronic means, we provide the information in a commonly used electronic format, unless an alternative format is requested. Whilst we provide the information requested without a fee, further copies requested by the individual may incur a charge to cover our administrative costs. The Company always aim to provide the requested information at the earliest convenience, but at a maximum, 30 days from the date the request is received. However, where the retrieval or provision of information is particularly complex or is subject to a valid delay, the period may be extended by two further months. If this is the case, we will write to you within 30 days and keep you informed of the delay and provide the reasons.
What if you hold information about me that isn’t correct?
Under the GDPR, you have the right to request rectification of any inaccurate data held by us. Where we are notified of inaccurate data, and agree that the data is incorrect, we will amend the details immediately as directed by you and make a note on the system (or record) of the change and reason(s). We will rectify any errors within 30-days and inform you in writing of the correction and where applicable, provide the details of any third-party to whom the data has been disclosed. If for any reason, we are unable to act in response to a request for rectification and/or data completion, we will always provide a written explanation to you and inform you of your right to complain to the Supervisory Authority and to seek a judicial remedy. In certain circumstances, you may also have the right to request from the Company, the erasure of personal data or to restrict the processing of personal data where it concerns your personal information; as well as the right to object to such processing.
Where can I find further information on the GDPR?
If you would like further details on the Regulation or are unhappy with the way your data has been handled, please contact the Supervisory Authority - The Information Commissioner’s Office (ICO). They can be contacted at: - Wycliffe House, Water Lane, Wilmslow, Cheshire, SK9 5AF. Telephone: 0303 123 1113 (local) / 01625 545 745 (national). Fax: 01625 524 510. Email: Web:
Where can I find further information about how Grant UK process personal data?
We are dedicated to safeguarding any personal data under our remit and process this information in accordance with our Privacy Policies, see:
How can I make a data protection complaint?
Every individual has the right to lodge a complaint with the supervisory authority - the Information Commissioner’s Office (ICO), where they consider that the processing of personal data relating to them infringes the General Data Protection Regulation (GDPR) or we have breaches data protection law. The ICO with which the complaint has been lodged, is responsible for informing the complainant on the progress and the outcome of the complaint, including the possibility of a judicial remedy where the supervisory authority does not handle a complaint or does not inform the data subject within three months on the progress or outcome of the complaint lodged. The ICO can be contacted at: - Wycliffe House, Water Lane, Wilmslow, Cheshire, SK9 5AF. Telephone: 0303 123 1113 (local) / 01625 545 745 (national). Fax: 01625 524 510. Email: Web:


If a household has to self-isolate during the coronavirus outbreak and is therefore unable to have their Grant product serviced, will the product's warranty be affected?

Grant UK fully understand that some customers may have to self-isolate for a considerable period of time and as such, will not be able to have their Grant product serviced. We are therefore issuing the following guidance.

While it remains important for all appliances, cylinders, stores, tanks, fuel lines and ancillary components to be serviced annually, Grant UK will continue to honour all warranties (on both Standard and Extended) beyond the normal service date up to the 30th September 2020 whether the appliance is serviced or not. This extension relates to Grant oil boilers, Grant Biomass boilers, Grant Aerona Heat Pumps and Grant Cylinders/Thermal stores.

This date may change in line with the recommendations of the UK Government and current information can be found on our website here.

It is imperative that the appliance and connected components are serviced as quickly as possible after this date to ensure trouble free operation.

Where can I buy Grant products?

Grant UK distributes through a network of independent and national plumbing and heating merchants. Please use our Merchant Search tool to locate a distributor near you.

What does ‘net zero carbon’ mean?

Net zero carbon refers to achieving a balance which ensures that the level of carbon dioxide within the atmosphere is not added to or increased. The Government has set the country a target of achieving net zero greenhouse gas emissions by 2050 which will mean that society, its behaviours and everything it produces, will need to collectively not increase the overall level of emissions, including carbon. Wherever possible, no carbon emissions should be produced but when they are, society needs to counteract these emissions with an environmentally friendly solution to absorb any excess carbon from the atmosphere.

What is ErP?
The Energy Related Products (ErP) Directive has been designed to aid the EU in achieving reductions in energy usage: carbon, NOx and SO2 emissions and other environmental issues such as noise and the use of refrigerants in heat pumps. The Directive is also designed to help consumers identify the most energy efficient products on the market with energy efficiency labelling. The ErP details energy efficiency requirements which appliances must meet and preferably exceed. Manufacturers must ensure that their products are prepared for the new legislation changes, incorporating product updates to improve efficiency levels (e.g. fitting high efficiency circulating pumps).
What is the Renewable Heat Incentive (RHI)?
The Renewable Heat Incentive (RHI) is a Government initiative introduced to encourage and reward people for using renewable fuels to heat their properties. There are two RHI’s - one for domestic homes and one for non-domestic (industrial, commercial, public sector, etc). The aim of the RHI scheme is to help the UK achieve its EU emission targets by 2020.
Can I add anything to my heating system to prevent it from freezing?
Yes, there are a number of products which may be used to give frost protection to domestic central heating systems.  For total system protection against freezing particularly during extended periods without electrical power, we recommend the use of a combined heating system antifreeze and corrosion inhibitor used in accordance with the manufacturer’s instructions.
Is Grant UK a member of RECC?
Grant Engineering (UK) Ltd is a member of RECC (Membership No. 00070263). In the unlikely event of a dispute arising around the installation of a small-scale renewable energy system that cannot be resolved through Grant Engineering (UK) Ltd, disputes can be referred to RECC for mediation. For a company to become MCS Accredited, they must comply with the Scheme’s standards which includes being a member of a certified alternative dispute resolution (ADR) provider. In October 2015, new legislation was introduced to promote the use of alternative dispute resolution ensuring that suitable options are made available in consumer disputes, with traders required to inform consumers whether they are willing to use ADR – this is when a certified ADR provider is needed. RECC ( is a certified ADR provider, aiming to guarantee a high quality experience for consumers wishing to buy small-scale renewable heating systems for their homes. Matters relating to the MCS Installer Standards can be referred to Grant Engineering (UK) Ltd’s MCS Certification Body. Their contact details are as follows: NAPIT, 4th Floor, Mill 3, Pleasley Vale Business Park, Mansfield, Nottinghamshire, NG19 8RL (t: 0345 543 0330 f: 0345 543 0332).
How can I make a general complaint to Grant UK?

We consider and respond to all complaints and issues, no matter how they are raised or what they refer to. We take every opportunity to resolve complaints at the first point of contact where possible. To make a complaint, please use the contact forms on this site, or alternatively email:

How do I find out if my boiler has a guarantee?
When a product is registered via our online system, we send an email confirmation with your guarantee paperwork detailing the product registered along with Terms and Conditions. If you have not received anything, please contact our customer services department on 01380 736920.
I have heard I can get a ten year guarantee on my oil boiler, is this correct?
We do offer a ten year guarantee on our VortexBlue range; however, this is subject to certain Terms and Conditions such as the product being installed by a Grant G1 installer and a Grant Mag One filter being fitted to the system. For details on how to find a G1 Installer, please visit our ‘Find an Engineer’ page.
What is the standard guarantee on your products?
All Grant products have a statutory 12-month guarantee. If the product is registered via our website within 30 days of installation, this is upgraded to a standard warranty: 2 years on oil boilers, biomass and air source heat pumps, 5 years on solar thermal, 2 years on cylinder components and 25 years on the cylinder body. These warranty periods are subject to Terms and Conditions and for more information please call 01380 736920.
How can I find G1 Installers and/or service engineers in my local area?

Grant UK’s Find an Engineer search facility allows homeowners to find local installers and engineers in their area. Simply click on ‘Find an Engineer’ under the ‘Support’ header and then enter your postcode. The search will then bring up a selection of G1 installers and service engineers based locally to you. You can also filter your search to suit your requirements.

Can G1 Installers offer extended guarantees on Grant’s renewable products as well as oil boilers?
G1 Installers can activate extended guarantees on the Grant products they are accredited to install. This can include Grant’s Aerona³ air source heat pumps, VortexAir Hybrid models and biomass boilers. In order to activate the longer guarantee periods, the G1 Installer must install the appliance in full accordance with the installation instructions and then register the product via their online G1 Portal.
My Grant appliance was installed by a G1 Installer so who should register my product?
If your Grant product was purchased and installed by a G1 Installer, it is your installer’s responsibility to register the appliance via their online G1 Portal. Once they have registered your product, your G1 Installer will receive a copy of the registration paperwork and they can then forward this through to you for your records.
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