Frequently asked questions – Trade

Information on Grant boilers and heating products

Oil condensing boilers

Oil-Fired Condensing Boilers

What’s the difference between the Euroflame and Vortex Boilers?

The Award Winning Vortex boiler was launched in 2001, in the subsequent years that followed there was a customer demand for a competitively priced ‘A’ rated boiler, the design team at Grant devised the Euroflame range to meet this growing consumer demand.

Both the Vortex and Euroflame are high efficiency boilers, the major difference being the efficiency, the Vortex efficiency is from 92.6% to 97%, whereas the Euroflame efficiency is 92.1% to 93% and both are ‘A’ rated boilers, there would be a difference in price with the Vortex being slightly more expensive.

The Vortex has a larger heat exchanger area which gives it a higher efficiency than the Euroflame, the Vortex module has a frost stat and a service switch inbuilt.

There are 28 model variants in the Vortex range and 9 model variants in the Euroflame range, there is a Grant boiler suitable for every domestic application.

The Grant range of oil fired condensing boilers account for the TOP 19 boilers on the Harp database.

Features and characteristics of both Vortex and Euroflame are:

  • The award winning Vortex stainless steel heat exchanger and turbulator baffle system for ultra high efficiency
  • All models are Harp Band ‘A’ rating
  • Factory fitted internal condensate traps to make sitting the appliance straight forward
  • The unique heat exchanger is covered by a 5-year guarantee.

All Vortex and Euroflame boilers are compatible with Grant’s EZ-fit flue systems, which include low-level, high-level, rigid and flexi vertical balanced kits and also flexible and external conventional flue packs.

What’s the difference between Seasonal efficiency vs Combustion efficiency

Seasonal Efficiency is the average annual efficiency achieved in typical domestic situations, and is confirmed by independent testing bodies.

These figures are verified on or A simplified explanation of Seasonal Efficiency is that this is the average efficiency of the boiler over a year, taking into account climate, housing conditions, occupancy patterns, and controls.

Combustion Efficiency is defined as the amount of heat released during combustion over the heating value of the fuel burned.

This is usually shown as the net efficiency on a digital flue gas analyser, and may be higher or lower than the Seasonal Efficiency, depending on the time of year and the heat load.

Should I have a Frost Stat fitted to my Boiler?

We recommend that Outdoor Boilers should have a Frost Stat fitted.  The Grant Vortex Module range is factory fitted with a Frost Stat set at 5ºC plus or minus 1ºC.  A permanent live is required with a frost stat.

For added frost protection on Grant Vortex Modules, fit a pipe thermostat on a return pipe, set at 30ºC and wired to number 5 & 6 on the control panel.  This will prevent the boiler heating the house unnecessarily.  A bypass must also be fitted when wired as above.

What boilers have Frost Stats fitted and what are they set to?

Frost stats come as standard on all Grant Vortex Outdoor Modules. They are set at 2°C plus/minus 1°C and require a permanent live to the boiler.

Is there anything I can do to help prevent freezing of a condensate trap?

 It is advisable to let your condensate run into a soil stack or the larger the diameter of pipe the better as this will help to prevent freezing water.  If your condensate trap is not run off into a soil stack pipe and its running into a smaller waste pipe then remove the bung on the condensate trap

What type of Fire Valve should be fitted to my Boiler

A fire valve is an essential part of the oil supply system.

It should be capable of cutting off the flow of oil outside the building in the event of a fire or overheat situation occurring within the appliance. The valve should be located outside the building before the point where the oil supply pipe enters the building. It must be activated by a remote sensor located over a pressure jet burner or a vaporising burner oil control valve, but in a position clear of any direct radiation or excessive heat.

What is the maximum distance you can run a low level flue horizontally?

The maximum horizontal length on a low level flue is up to 4 metres including one 90° or two 45° elbows.

What type of Oil Filter should be fitted to an oil tank?

Filter bodies should either be constructed of metal and have disposable filter media or they should comply with OFTEC standard OFS E104

Where an oil strainer (having a filtration size no greater than 150 microns) is fitted at the oil tank an additional filter (having a filtration of 70 microns or less) should be fitted downstream to protect both the appliance and other oil pipe equipment and components. 

What is the test switch for on outdoor modules?

A test switch is on all Grant Vortex outdoor modules and it is there to help an installer or service engineer test the boiler to fire up the burner without having to go back inside the house or if the customer is not home when installer/service engineer calls. The test should be left in the off position when boiler is in operating mode.

What is the range on the control thermostat on the Grant Vortex Range

The control thermostats on all the Grant Vortex boilers range from 55°C to 75°C and has a very short turn on the thermostat (roughly a quarter turn).

Can you fit an oil boiler and still comply with Part L?

Yes the Grant Vortex oil boilers can still be fitted in new build houses. The back stop levels would have to go below the maximum U-Valves in the house and the air permeability would have to be below 7m3/hm2.

Read our article Compliance with Part L of the Building Regulations for more information.

wood pellets

Wood Pellet Boilers

How much space is required to install the boiler and hopper?

Suitable space must be allowed around the boiler for servicing and maintenance. Full details of the precise minimum clearances are to be found in the Installation and Servicing instructions provided with the boiler.

Typically, an overall floor area of 1700mm wide x 1500mm deep will be required to locate the boiler/hopper and provide the clearances required.

See Siting & Maintenance of Grant Biomass Wood Pellet Boilers for more information.

What has to be done to fit a Wood Pellet boiler in compliance with Part L?

A lot of builders, engineers and BER assessors think that heat pumps and P.V. are the only way to comply with Part L Regulations. However, Grant Engineering can show examples of how Condensing Wood Part Boilers comply with Part L.

Read our article Compliance with Part L of the Building Regulations for more information.

Can the Grant Spira wood pellet boiler be installed outside?

No. Grant Spira wood pellet boilers must be installed in a damp free environment along with the accompanying pellet hopper. The boiler can be located in an outbuilding, etc. but must not, under any circumstances be exposed to the elements (e.g. located under a car port or lean to canopy).

See Siting & Maintenance of Grant Biomass Wood Pellet Boilers for more information.

Are there any special requirements for the base on which the boiler and hopper are installed?

Yes. The base must conform to the requirements of Building Regulations. Full details are given in the Installation and servicing instructions supplied with the boilers.

See Siting & Maintenance of Grant Biomass Wood Pellet Boilers for more information.

What type of heating system can a Grant Spira wood pellet boiler be used with?

Grant Spira wood pellet boilers can be used with 2-pipe, fully pumped hot water heating systems – either open-vented or sealed system – using radiators and/or underfloor heating.

Sealed heating systems must incorporate a suitably sized expansion vessel, a pressure gauge and approved filling loop. The 2.5 bar pressure relief valve required is supplied with the boiler.

What type of heating system controls can be used with a Grant Spira wood pellet boiler?

Grant Spira wood pellet boilers can be used with most commonly installed domestic heating control systems, e.g. Y-plan and S-plan type control systems, where a programmer and room thermostat will control the operation of the boiler to the requirements of the householder.

What size of heating system is the Grant Spira wood pellet boiler suitable for?

Grant Spira wood pellet boilers are fully modulating and their output will automatically be adjusted to meet the changing demand of the heating system to which it is fitted, however the boiler must be capable of operating at its full output, as this is a requirement for commissioning the appliance.

The smaller 6 – 26kW models can be used for systems with a maximum heat load of 26kW, whereas the 9-36kW model can be used for larger heating systems of up to 36kW heat load.

It is also possible to combine two units with a unique central hopper to achieve a maximum output of 72kW, which can prove to be a very cost effective solution for larger domestic and smaller commercial installations.

Can a Grant Spira wood pellet boiler be fitted as a replacement boiler on an existing heating system?

Yes, provided that the existing system is chemically cleaned and flushed, and complies with current Building Regulations. The existing control system may also be used providing that it also complies with these regulations. If not the system and/or controls will need to brought in line with these requirements.

How should a Grant Spira wood pellet boiler be sized?

As with all boilers, a full heat loss calculation for the property should be made to determine the heat load that the boiler will be required to meet, under design conditions. If the heating system includes a circuit to a hot water cylinder then an allowance for water heating should normally be included in determining the final heat load to be met by the boiler.

Is a buffer tank required?

No, while many other makes of pellet boilers require a buffer tank the Grant Spira Condensing Wood Pellet boiler does not, this is an additional saving for the householder.

What heating flow temperature will the Grant Spira wood pellet boiler produce?

Grant Spira wood pellet boilers are condensing wood pellet boilers and as such are intended to operate at lower flow and return water temperatures than conventional boilers. The water temperature from the boiler can be adjusted on the burner control panel, but should not exceed 75oC.

How efficient are the Grant Spira wood pellet boilers?

The Grant Spira is a condensing wood pellet boiler with a modulating burner and has exceptionally high efficiency levels. The 6-26kW model has a tested and approved full load efficiency of 97.4% and the 9-36kW model 93.1%.

This is comparable with high efficiency condensing domestic oil fired boilers (and better than many high efficiency gasfired boilers), making the Grant Spira both an energy efficient and ‘Green‘ alternative to fossil fuel burning boilers.

What is unique about the Grant Spira wood pellet boiler?

Grant Spira wood pellet boilers benefit from the use of award winning condensing technology, originally developed for Grant’s market leading Vortex oil-fired boiler range. This, in conjunction with the all-new fully modulating pellet burner, has resulted in an extremely efficient range of renewable home heating appliances. Higher efficiencies, coupled with lower and more stable fuel costs, creates a very environmentally and consumer friendly heating solution.

What type of flue system is required for a Grant Spira wood pellet boiler?

Grant Spira wood pellet boilers must be installed with a Grant ‘Black’ flue system. This is an insulated twin wall stainless steel flue system with a semi gloss black finish specifically designed for use with Grant’s Spira condensing technology. It is available in one size – 125mm (5”) internal diameter, suitable for both sizes of Spira boiler. The Black flue system also includes a 125mm flexible flue liner for use with an existing chimney.

Who can install, commission and service a Grant Spira wood pellet boiler?

Only Grant trained and accredited wood pellet boiler installers can install the Grant Spira wood pellet boiler. Courses are available via the Grant Training Academy and can be booked by calling (057) 912 0089.

How often should a Grant Spira wood pellet boiler be serviced?

In order to ensure efficient and safe operation, Grant Spira wood pellet boilers must be serviced annually when amongst other things, the primary and condensing heat exchangers, combustion chamber, flue fan box and burner, must all be cleaned of any ash deposits and the burner re-set for a further year’s operation. The boiler will indicate when this is due, by displaying a ‘SERVICE’ message on the burner control panel. This service interval is based on the actual running time of the burner and thus may vary in length depending on the degree of use of the boiler.

Is the Grant Spira MCS approved?

Yes, all boilers within the Grant Spira Wood Pellet Range are MCS approved.

Solar Thermal system

Solar Thermal System

5 Things you should know about Grant Solar Panels

  1. The lifetime of Grant Flat Plate Solar Panels can be up to 40 years compared to 12 years for tubular solar collectors
  2. In comparison to the high costs of other energy sources solar energy provides a saving of up to 70% in hot water or 30% of the total heating and hot water costs in a year.
  3. The Grant Sahara Flat Plate has an efficiency of 79% and is NSAI Agrement approved.
  4. SEAI grants are available under the SEAI Better Energy Homes Scheme
  5. Grant Engineering (Ireland) Limited offer a 5 year warranty on all solar panels

Advantages of Grant solar Panel

  • Grant Solar Panels can provide up to 70% of your hot water needs FREE for the year.
  • Grant Solar Panels are NSAI Agreement Approved for on roof and in roof systems.
  • The lifetime of Grant Solar Panels can be up to 50 years compared to tubular solar collectors whose lifetime is greatly shorter.
  • The Grant Solar Panel is comprised of 3.2mm low iron glass which makes it  more robust and shock resistant than the tubes.
  • The Grant Solar Panels are the most affordable efficient panel on the market with an efficiency rating of 79.1% with a heat loss co-efficient of 3.307.
  • The Grant Solar Panel is aesthetically pleasing with its dark frame and glass and it means you don’t see the pipes in the panels and it blends in better with your typical Irish roof slates or tiles.
  • The Grant Panels can be used in many situations, on roof, in roof, flat roof, portrait or landscape and can be used with slate tile or corrugated roofs.
  • Our Solar Systems are designed to be plumbed with ½ inch pipe which is quicker to heat and cheaper to plumb.
  • The Grant Solar Panels are made in Germany.
  • Grant Engineering provides FREE training both in the factory and on site for our Solar Panels.
  • Grant can provide a full range of Solar Cylinders in both copper and stainless steel to suit all applications.

How to service a Grant Solar System?

It is always recommended that you service the solar systems regularly:

  • Make sure there is no air in the system
  • Check expansion vessel and make sure correct air pressure in the vessel
  • Check gylcol in system, 40/60 mix is what is required. Check with refractometer
  • Go through the settings on the controller, make sure the settings are correct
  • Check pressure on system when the system is cold, normal running pressure between 1.5 and 2 bar
  • Visually check out panels on roof and that probe is correctly installed
  • Check hot water cylinder is installed as per manufacturer’s instructions
  • Make sure cylinder solar sensor is correctly located and securely fitted
  • Make sure expansion vessel on hot water cylinder is correctly charged.

If you are interested in becoming a Grant Solar Installer or a Solar Service Engineer please contact us on 057 9120089

Hot water cylinders for solar

Cylinder Range

What is the range of cylinders and what are the available sizes?

Grant DuoWave Cylinders, unvented hot water cylinders indirect solar twin-coil models for renewable applications — sizes range from 200-500 litres in stainless steel and copper.

Grant DuoWave Plus Cylinders, open-vented or unvented hot water cylinders indirect triple-coil mains pressure models for combining solid fuel, biomass, gas, electric or oil-fired boilers and solar thermal systems — available in a 250,300 and 500 litres in stainless steel and copper.

Other cylinder sizes and types are available on request up to 2000 litres.

What is supplied in the unvented kits?

1 x Expansion vessel, hose and bracket
1 x 15mm/22mm Tundish
1 x 2 bar(copper) or 3 bar(stainless steel) inlet manifold assembly
1 x Installation and user instruction manual
2 x Dual stats
1 x Motorized valve
1 x Drain Cock

What coils are in the cylinders?

Models incorporating internal coils are constructed from 20mm or 25mm corrugated stainless steel tube and 28mm copper tube, giving maximum heat transfer, high efficiency and quick recovery.

What approvals have the grant cylinders have?


All cylinders are manufactured in accordance with BS EN 12897 the specification for unvented hot water storage vessels. They all comply with Building Regulations G3 and Water Regulations. Hot water cylinder performance complies with the requirements BS6700, BS1566 and BS7206 and meets the NHBC criteria.


All cylinders are fully integrated within the Code of Practice for the installation and commissioning of central heating systems – Benchmark. The aim of the scheme is to advance professionalism of the heating industry and increase levels of customer satisfaction

Grant Triple Pass Back Boiler

Triple Pass Back Boilers

Who can install a Grant boiler?

Any gas installation work should only be carried out by a qualified installer.

Can a back boiler be fitted onto a sealed system?

No, it must be fitted to an open vented system only.

Can this boiler be used as part of a dual heating system ie. Oil or gas?

Yes, once it is piped correctly and fitted according to manufacturers instructions.

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