As the UK increasingly moves toward electrifying heating, mechanical and electrical consultants are facing a familiar challenge: how to keep air source heat pumps (ASHPs) running smoothly in cold weather without losing performance. At Strebel UK, we have integrated a solution to this problem with our latest range of heat pumps that use vapour injection technology. This innovation helps boost heating output, efficiency, and system resilience—especially in colder climates where traditional heat pumps can struggle.
In simple terms, vapour injection (or enhanced vapour injection, EVI) is a clever way of improving how heat pumps work in low temperatures. It enhances the refrigeration cycle by adding a subcooling circuit. This process involves injecting partially expanded vapour refrigerant into the compressor at an intermediatory point, which essentially provides an additional and enhanced refrigerant compression process. The result? increased heating capacity and a system that can provide high flow temperatures at ultra-low ambient conditions.
And thanks to vapour injection, our systems work more efficiently, especially in the 35–55°C temperature range that’s common for underfloor heating or oversized radiators. This means lower energy use, reduced carbon emissions, and better overall performance—helping engineers hit energy efficiency targets and improve EPC and SAP/SBEM scores.
Vapour injection opens more options for system designers, especially when working on hybrid or mixed-use buildings. The broader operating range means you can confidently specify Strebel Air Source Heat Pumps for projects where performance and thermal reliability are key, even in high-load or complex installations.
At Strebel UK, we don’t just provide great products—we’re also here to support M&E consultants, contractors and end users throughout the whole process. From initial sizing and heat loss calculations to commissioning and system integration guidance, the Strebel team are here to support from day one. Our goal is to make vapour-injected ASHPs an easy, reliable choice for engineers looking for low-carbon solutions that perform in the real-world UK climate.
We have also just released our latest CIBSE accredited CPD that explores EVI in more detail, how the technology is integrated into the heat pump and the performance benefits compared to standard refrigeration systems.
To book please follow the link below which also includes full technical specs, selection tools, TM65 embodied carbon data, IOM manuals and more – www.strebel.co.uk