Frequently asked questions

What is the 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 it 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 nonrenewable 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 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.

Where can I buy the Grant VortexAir Hybrid?

Grant UK sell products through a network of independent and national merchants. You can find your local stockists on our support page by using our online merchant search facility. Alternatively, please call our Sales Department on 01380 736920.

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. Grant has a calculator that allows installers to provide an approximate estimate of the payback period, including potential RHI payments (where applicable), for the VortexAir Hybrid compared to the installation and running cost of a high efficiency condensing oil boiler. Please call our pre-sales technical team for further information.


IMPORTANT – Grant UK strongly recommends that a MagOne in-line magnetic filter is fitted in the heating system pipe work. This should be installed and regularly serviced in accordance with the installation instructions.

Hybrid Case Studies