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Grant Vortex Pro 21kW Internal Combi Boiler

Part Number : H018354

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Boiler Type

  • Electronic Condensing Internal Combination Boiler
  • Sleek Finish
  • Fitted with Tried and Trusted Riello RDB Lo-NOx Burner

Grant Vortex 21kW Internal Combi Boiler

The intelligent Grant Vortex Pro Combi incorporates the latest Riello RDB low NOx burner technology and combines it with the award winning Vortex stainless steel heat exchanger.

The Grant Vortex Combi unique design features large heat exchangers which, due to their low water content and larger surface area, vastly increase the hot water performance available and mixing valves are pre-set at 50°C, controlling accurately the hot water draw off temperature from the boiler. There are two very accurate electronic temperature controls which allow the boiler to operate in condensing mode on central heating, whilst maintaining its instant hot water production.

Features and Benefits:

  • Electronic Condensing Internal Combination Boiler
  • Sleek Finish
  • Fitted with Tried and Trusted Riello RDB Lo-NOx Burner
  • Exceptionally Quiet Operation
  • Unique Grant Vortex Stainless Steel Heat Exchanger
  • Front Service Access
  • Annual Efficiency: 89.5- 91.6% (Gross SAP2009)
  • 21kW Output
  • Size: 860mm x 614mm x 606mm (HWD)
  • 5 Year Manufacturer Guarantee (When Installed by a G1 Accredited Installer)

Technical Images


Technical Specifications

Manufacturer Guarantee 5 Years
Max Heat Output 21
Boiler Type Combi Boiler
Manufacturer Part Number VTXCOMBI21

Frequently Asked Questions

  • What is the difference between the Grant Vortex boiler and the Grant VortexBlue boiler?

    The Grant Vortex boiler range uses a low NOx yellow flame burner, whereas the Grant VortexBlue boilers uses an ultra-Lox blue flame burner. The combustion head on the VortexBlue’s burner is specially designed to re-circulate the combustion gases. Re-circulating the combustion gases in this way significantly reduces NOx emissions and produces the clean blue flame which gives the technology its name.

  • What size of boiler do I need?

    Before selecting your new boiler, Grant recommend requesting that your installer performs a heat loss estimation of your home to ensure that you select the most appropriate size and type of boiler. Heat loss depends on the efficiency of any heat retaining methods that can be implemented in your home, for example loft insulation, double glazing, cavity wall insulation, draught proofing, etc. These practises could mean that your new boiler may need to be smaller than the one that it is replacing.

  • Can I run a new Grant Vortex boiler on an older heating system?

    As long as the system is thoroughly cleansed and updated to fully pumped operation, it is possible to run a Grant oil boiler on an older heating system.

  • Can I use my existing flue system for my new Grant boiler?

    Unfortunately, in most cases you will not be able to use an existing flue system with a new boiler. Condensing boilers have a lower flue gas temperature which can lead to harmful condensation in the chimney/flue. You will need to ensure that you install a Grant approved flue system which is stainless steel and sealed securely at the joints to prevent it from leaking. All Grant external modules come with a factory fitted flue system.

  • How often should a Grant boiler be serviced?

    Grant recommend that an oil boiler operating on kerosene should be serviced every twelve months, and an oil boiler operating on biofuel or gas oil should be serviced bi-annually.

  • I’m worried that my oil supply could run out, how would this affect my system?

    Grant recommend keeping your oil tank filled as required to ensure that the oil does not run out. If your oil supply does run out, you should contact a qualified oil heating engineer to bleed the system once the tank has been filled. It is recommended that after filling, a period of about an hour is allowed for any sediment that has been disturbed in the oil tank time to settle before operating the boiler. With an oil boiler, there is a risk of air and contaminants that sit in the bottom of your oil tank (water and sludge) reaching the oil line and ultimately the burner. This will affect the operation of your boiler, however maintaining an adequate oil level in the tank can prevent this from happening and causing further damage.

  • What is the typical hot water performance levels of Grant’s Vortex Internal Combi boilers?

    The Vortex Internal Combi 21kW heats 15 litres per minute at an average temperature of 50°C (recovery time 4 minutes approx. based upon 100 litre draw off). The Vortex Internal Combi 26kW including the Combi XS model heats 17 litres per minute at an average temperature of 50°C (recovery time 4 minutes approx. based upon 100 litre draw off). The Vortex Internal Combi 36kW heats 20 litres per minute at an average temperature of 50°C (recovery time 3 minutes approx. based upon 100 litre draw off).

  • What type of flue should I install alongside a Grant Vortex Internal Combi boiler?

    All of Grant’s Vortex Internal Combi boiler models can be connected to a conventional flue system or balanced flue system, as required. All of the compatible flues are available from Grant’s EZ-Fit Flue range.

  • Is top access required for servicing Grant Vortex Internal Combi boilers?

    With all of Grant’s Vortex Internal Combis, sufficient clearance should be allowed at the front of the boiler to allow for the burner and baffles to be removed during servicing. For the 21kW and 26kW output Combi models, these boilers can be serviced via front access but it is preferable to have the option to access from the top as well. For the 36kW Internal Combi model, a removal section of the worktop is necessary to provide top access to the boiler for servicing as some of the components are located at the top of the unit.

  • What is the slimline version of the Grant Vortex Internal Combi boiler?

    Grant’s Vortex Internal Combi XS model is a 26kW boiler which is only 515mm wide. This boiler is a compact combi and has almost identical characteristics on both combustion efficiency and domestic hot water performance as its larger version and utilises all of the existing components.

  • What size are the flow and return connections on Grant Vortex Internal Combi boilers?

    The 21kW and 26kW Vortex Internal Combi boilers, including the XS model, are supplied with and use 22mm flow and return connections. Meanwhile, the larger model, the 36kW boiler, uses 28mm flow and return connections.

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