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Vaillant Hybrid Heating System

Rob Wells
By: Rob Wells
Updated: 2nd January 2023

If you're interested in lowering your heating bills by installing an air source heat pump but have concerns about replacing your boiler completely, the aroTHERM hybrid air-to-water heat pump by Vaillant could be your solution.

The aroTHERM hybrid heat pump is ideal for homes which can't be adequately heated by an air source heat pump alone (e.g. homes with significant heat losses) or homes wanting to keep their boiler but also reduce running costs and / or carbon emissions. The heat pump can be integrated into your current central heating to work with your existing boiler or installed at the same time as a new replacement. The aroTHERM hybrid is designed to be used alongside a gas, oil or LPG boiler and is available in four sizes to suit the heating and hot water demand of a range of homes.

5kW 8kW 11kW 15kW
Width (mm) 970 1103 1103 1103
Height (mm)> 834 975 975 1375
Depth (mm) 408 463 463 463
Net weight (kg) 86 102 126 165
ErP rating at 35°C A++ A++ A+ A++
ErP rating at 55°C A+ A++ A+ A+

How hybrid heating works

A hybrid heating system includes both an air source heat pump and a boiler. The heat pump is installed outside your home and integrated into your existing heating system*.

The system is intelligent enough to monitor the outside temperature as well as your energy / fuel tariff to decide which of the two heating systems is the most efficient way to heat your home and hot water. It will then automatically switch to the more efficient system to save you energy and money.

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The aroTHERM hybrid heat pump by Vaillant does this via the Vaillant VRC 700 / VRC 700f operating control. This control assesses the temperature outside, calculates your energy costs and then communicates with the heat pump and boiler to ensure the best system is running.

The VRC 700 control can either run your heat pump by itself, the Vaillant boiler by itself or both at the same time. The homeowner can override the control at any time.

*In some cases it may be necessary to replace some radiators with larger models as air source heat pumps are most effective when heat is distributed over a larger surface area.

Why install a Vaillant hybrid heat pump?

Installing a hybrid heat pump has 3 key benefits:

  • More energy efficient heating system (rated up to ErP A++) for cheaper energy bills
  • Less reliance on fossil fuels for reduced carbon emissions which is better for our environment
  • Longer lasting system as the heat pump and boiler share the workload, reducing

These benefits are generally true of any hybrid heating system, so why choose a Vaillant aroTHERM hybrid heat pump?

Trusted Brand

Vaillant are leading manufacturer in the heating industry; the brand can be traced all the way back to a small craft workshop in Germany in 1874 where a tailor, Johann Vaillant, started a coppersmith and pump manufacturing business. The Vaillant family remain involved in the company today.

Compact size and simple to install

The aroTHERM's compact dimensions mean that the 5kW, 8kW and 11kW models should fit easily under a standard window outside your home. In most cases the heat pump fan unit meets the Permitted Development Regulations so you shouldn't need planning permission (although it's always wise to check). Vaillant have also included a 'setup wizard' for the first installation to help speed up the commissioning process and hopefully save you money on labour costs.

'Quiet Mark' approved

The aroTHERM is 'Quiet Mark' approved as it has 'ultra-quiet operation' noise as low as 58dB. As the heat pump is installed outside your home and by a window this could be a big attraction over some other models.


The hybrid pump is controlled by the VRC 700 which features the unique triVAI® intelligent control system. This means you should be able to simply set your desired temperature programme (7 days, weekdays and weekends or 24-hour time periods) and let the VRC 700 take care of the day to day running. It will automatically adjust for the weather conditions and best energy. You can also override the VRC 700 control if you wish to.

3Control from anywhere

In addition to being able to control multiple heating systems the VRC 700 can also be controlled via the VRC 700 app on your phone so you can control your boiler and heat pump from your smart device wherever you are.

Multiple energy tariffs

The VRC 700 will hold 3 energy tariffs so it can switch to the appropriate energy costs automatically.

Flexible system

Unlike some other hybrid pumps the aroTHERM is compatible with oil boilers as well as gas and LPG. If you have a larger home you can install up to 7 heat pumps to meet your hot water demand or, if your family or home expands in the future, you can add extra heat pumps at a later date. The VRC 700 is also compatible with ambiSENSE thermostatic radiator valves; this means you can individually programme radiators to different temperatures and control them from the app.

Anti-vandalism design

The heat pump itself is a solid unit with in-built anti-vandalism measures so you don't need a cage to protect it.

Reliable and low maintenance

As you're switching between 2 technologies, neither element has to work as hard which reduces wear and tear on both. This should result in simpler maintenance, fewer repairs and a longer life for your boiler. The pump also features a blue fin coated evaporator with anti-hydro coating to deliver both improved performance and extra protection against corrosion.

Eligible for Renewable Heat Incentive

The aroTHERM hybrid heat pump is MCS accredited and so is eligible for the government's RHI payments for 7 years. However, you should always check with the RHI scheme before committing.

Is a Vaillant aroTHERM hybrid right for you?

The aroTHERM hybrid is recommended for homeowners who want to maximise energy savings and reduce their reliance on the boiler and fossil fuels, but either don't want to or can't do without their boiler completely. It's a particularly good option for homes with lower levels of insulation where a heat pump by itself wouldn't be an effective solution as the boiler act as a backup / boost in cold weather.

Air source heat pumps in general are recommended for use with radiators which emit a lower temperature but over a larger surface area and underfloor heating systems.

You'll need to have enough outside space for the heat pump fan unit to be installed. The size of this will vary slightly depending on whether you choose a 5kW, 8kW, 11kW or 15kW model.

Vaillant aroTHERM hybrid heat pump costs

To install a hybrid heat pump system you are looking at around £4,000 – £8,000, but this is dependant on many factors such as the size of your home and any other work needed during installation. For example, the price will increase if you need to replace radiators in your home.

To get accurate prices for a hybrid heating system you should contact several Gas Safe registered heating engineers and compare at least 2-3 quotes. A professional will be able to give you advice about the best heating solution for your home and give you a tailored quote for the work.

You can get up to 3 free, no obligation quotes from Gas Safe engineers here at Boiler Guide. Simply send us an enquiry and we'll find you quotes from up to 3 engineers in your area.

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Rob Wells

About the author

Rob Wells

Rob is another of our resident home heating experts. He manages our external partnerships, making sure you get the most up to date information.

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