Vaillant aroTHERM plus

What makes the aroTHERM plus a good choice

A proven product

The aroTHERM plus has been installed in UK homes for several years. That matters. There is a well-developed body of knowledge among installers about how to set it up correctly, how to commission it for maximum efficiency, and what to expect from it in different property types. With a newer product, that knowledge takes time to build. With the aroTHERM plus, it already exists.

R290 refrigerant

R290 is propane. It is a natural refrigerant with excellent thermodynamic properties, meaning the heat pump can extract heat efficiently even at low outdoor temperatures. The low global warming potential of R290 also means this system has a far smaller environmental footprint over its lifetime compared to older F-gas systems.

Size range

The 3.5 kW to 12 kW range covers most UK homes. A proper heat loss calculation is the only reliable way to determine which size you need. At Heat Geek, every installation begins with a full heat loss calculation. Getting the size right matters: an oversized heat pump cycles on and off too frequently, reducing efficiency and increasing wear.

Flow temperature

The aroTHERM plus can reach 75 degrees flow temperature. In practice, you will rarely need this. A well-designed heat pump system with correctly sized radiators or underfloor heating should run at flow temperatures well below 55 degrees for most of the year. The ability to reach 75 degrees is useful for anti-legionella hot water cycles and for homes where the heating system has not yet been fully upgraded.

Weather compensation

Like all Vaillant heat pumps, the aroTHERM plus works with weather compensation via the sensoCOMFORT controller. Weather compensation adjusts the flow temperature based on outdoor temperature. Warmer outside means lower flow temperature, which means higher efficiency. This is one of the most important factors in heat pump running costs, and it is something many installations fail to configure correctly.

What to consider

R290 Protective Zone

The aroTHERM plus requires a 1-metre exclusion zone around the unit in all directions. This zone must be free from ignition sources: no plug sockets, no switches, no openable windows or doors within that radius. In most UK gardens this is manageable, but on compact urban plots it can limit where the unit can be sited. If exclusion zone clearance is a concern, the aroTHERM pro's Flexible Space Function may be a better fit.

Installation quality

The aroTHERM plus is a capable heat pump. How it performs in your home depends less on the unit itself and more on how it is installed and commissioned. Correct sizing, appropriate radiator or underfloor heating output, proper weather compensation setup, and correct hot water cylinder pairing all have a bigger impact on efficiency and running costs than the hardware specification alone.

aroTHERM plus vs aroTHERM pro

Vaillant launched the aroTHERM pro in 2026 as a companion product to the plus. Both use R290, both use the sensoCOMFORT controller, and both are built on the same core engineering platform. The pro has Flexible Space Function, which reduces the exclusion zone to below the unit only when active. The plus does not. The pro comes in anthracite; the plus is white. The pro is available in 5 kW, 7 kW, and 11 kW; the plus covers 3.5 kW to 12 kW. The pro is typically priced lower.

For most homes, either will do the job well. The aroTHERM pro's Flexible Space Function makes it the stronger choice for properties where outdoor space is limited. The aroTHERM plus covers a wider size range and has a longer track record.

The aroTHERM plus and hot water

A heat pump cannot provide space heating and hot water simultaneously. You need a hot water cylinder to store hot water so the heat pump can focus on heating the home when needed. The aroTHERM plus is compatible with a range of cylinders. For maximum efficiency, cylinder choice and design matter. A cylinder with a large, well-positioned coil and good stratification will allow the heat pump to run at lower flow temperatures, which improves efficiency significantly.

At Heat Geek, we often use the Heat Geek Super Cylinder, designed to maximise heat pump efficiency. It is independently monitored and consistently produces hot water at 400 to 550% efficiency when paired with a well-commissioned system.

Boiler Upgrade Scheme grant

The Vaillant aroTHERM plus is eligible for the Boiler Upgrade Scheme (BUS) grant. The current grant value for an air source heat pump is £7,500 for homes on gas and £9,000 for those on oil or LPG. This is applied at the point of installation and reduces the upfront cost of the system. Your installer claims the grant on your behalf. You do not need to apply separately.

The aroTHERM plus is a dependable, well-supported heat pump with a strong track record in UK homes. Like any heat pump, it will only perform to its potential if it is correctly sized, installed, and commissioned. If you are considering it for your home, start with a heat loss calculation. Everything else follows from that.

Key specifications