M&E Contrax Resources
Vaillant Heat Pumps
Resource Highlights:
Vaillant offers several heat pump options, the best choice depends on whether you need space heating, hot water, or both.
aroTHERM plus is an air source heat pump designed to deliver heating and hot water with a strong focus on efficiency.
aroTHERM split uses a two module setup, with indoor and outdoor units, and is designed to provide heating and hot water for a wide range of homes.
flexoTHERM is a multi source system that can use air, ground, or water as the heat source, which can be useful for certain properties and larger demands.
aroSTOR is a compact domestic hot water heat pump, designed for homes with higher hot water demand, available in 200 and 270 litre models.
Which model is right for your home or business?
Vaillant heat pumps are a popular choice in the UK because the range covers different property types and installation approaches, from air source heating and hot water systems to multi source options and dedicated hot water heat pumps. Vaillant’s UK line up includes models such as aroTHERM plus, aroTHERM split, flexoTHERM, and aroSTOR.
This guide is written to help you choose the right option based on how your property works, not just brand names. It explains what each model is designed for, what an installer will check, and what questions to ask before you commit.
Model specifications and availability can change, always check Vaillant’s official product pages for the latest details.
aroTHERM plus
What it is
The aroTHERM plus is Vaillant’s air source heat pump designed to provide heating and hot water, and is positioned by Vaillant as a high performance, high efficiency option with an A+++ energy efficiency class.
Best suited to
Homeowners who want a modern air source system designed around efficiency
Properties where the system can be properly sized and commissioned
Households looking to pair with a hot water cylinder and suitable controls
Vaillant notes the aroTHERM plus is intended to be paired with a hot water cylinder and indoor unit, for a wide range of properties.
What your installer should check
Heat loss, insulation levels, and room by room heating demand
Radiator sizing or underfloor heating suitability
Hot water demand and cylinder sizing
Outdoor unit placement, airflow, noise considerations, and pipe routes
aroTHERM split
What it is
The aroTHERM split is a refrigerant split air source heat pump system, Vaillant describes it as consisting of two modules, an indoor wall mounted unit and an outdoor unit, designed to provide heating and domestic hot water comfort.
Best suited to
Homes needing heating and hot water with a two unit approach
Installations where indoor and outdoor module positioning offers advantages
Installations where indoor and outdoor module positioning offers advantages
Vaillant notes flexible installation options, including wall mounted or floor standing outdoor siting, and references installations up to 15m away in some setups.
What your installer should check
Indoor unit location, access, and serviceability
Outdoor unit siting and pipe routing
Heating emitters and hot water requirements
Electrical supply and controls
flexoTHERM
What it is
The flexoTHERM is Vaillant’s multi source heat pump, Vaillant states it can use environmental energy from air, ground, or water to heat your home efficiently, with hot water preparation tailored using a Vaillant cylinder.
Vaillant’s professional guidance also notes flexoTHERM can be connected to a ground collector or borehole system to provide efficient heating and hot water.
Best suited to
Properties with the space and permission for ground loops or boreholes
Sites where ground source or water source approaches are viable
Larger domestic properties or commercial buildings where design flexibility helps
What your installer should check
Available heat source options, ground loop feasibility, borehole feasibility, or air source configuration
Site constraints, permissions, access and trenching scope
Heating distribution, emitters, cylinder sizing, and controls
Plant room considerations for larger systems
aroSTOR
What it is
The aroSTOR is a compact hot water heat pump, Vaillant describes it as suitable for homes with high hot water demand, available in 200 and 270 litre models, with an integrated control and quiet operation.
In other words, it is typically used for hot water only, rather than whole home space heating.
Best suited to
Homes that need an efficient hot water solution
Properties where a standalone hot water heat pump fits the brief
Some small business settings with consistent hot water demand
What your installer should check
What your installer should check
Install location, ventilation, condensate routing, and service access
Whether it is standalone, or part of a wider system design
How to choose the right Vaillant heat pump
Choosing between models usually comes down to three decisions.
1) Do you need heating and hot water, or hot water only?
Heating and hot water, consider aroTHERM plus or aroTHERM split, and in some cases flexoTHERM depending on site suitability.
Hot water only, aroSTOR is designed specifically for that role.
2) What heat source is realistic for your property?
Air source suits most homes, where siting and design are workable.
Ground source or water source can be excellent but depends on land, permissions, and groundworks, which is where flexoTHERM comes in.
3) What changes might your property need?
The most common factors that affect performance are:
Insulation and heat loss
Radiator sizing, or underfloor heating suitability
Hot water cylinder compatibility and sizing
Controls, zoning, and commissioning quality
A good installer will start with a proper survey and heat loss assessment, then recommend the right approach.
Grants and funding | Boiler Upgrade Scheme
If your property is in England or Wales, support may be available through the Boiler Upgrade Scheme (BUS) for eligible heat pump installations.
Servicing and long term care
Heat pump performance over time depends on:
Correct commissioning and settings at handover
Keeping airflow clear around the outdoor unit
Monitoring performance trends across seasons
Periodic professional checks as recommended by your installer
Frequently Asked Questions
Often yes, but suitability depends on heat loss, insulation, and emitter sizing. Many older homes work well with heat pumps when the system is designed properly.
Vaillant describes aroTHERM split as a two module system with indoor and outdoor units, while aroTHERM plus is positioned as a high efficiency air source option for heating and hot water. The best fit depends on installation constraints and system design.
aroSTOR is positioned as a domestic hot water heat pump solution, it is typically used for hot water rather than whole home space heating.
Vaillant describes flexoTHERM as a multi source heat pump that can use air, ground, or water as the heat source, which can be useful when ground loops or boreholes are viable.
Yes. Heat pumps can pair well with solar PV and battery storage, depending on your usage profile and system design.
Download a copy of this resource
Our resources are available for you to download, enter your details below and we will e-mail you a download link.
