Introducing the iStop PLUS: Altecnic’s latest compact anti-freeze valve


Altecnic, the UK’s leading supplier in hydronic solutions and part of the Caleffi Group, has launched the new compact anti-freeze valve, the iStop PLUS into the UK market.

With a compact design and the ability to install the valves vertically in parallel providing a solution for the most restricted spaces.

Why the iStop PLUS Stands Out

Setting the standard in efficiency and convenience, the iStop PLUS boasts a compact size, as well as a sensor on the side, differing to traditional anti-freeze valves, offering remarkably small dimensions without compromising performance.

Here are some of the key benefits:

  • Compact Size: Ideal for installations where space is at a premium.
  • Vertical Parallel Installation: Allows for a pair of valves to be installed in parallel without minimum spacing requirements.
  • Extreme Sensitivity to Water Temperature: Heightened responsiveness to ensure prompt and precise performance.
  • High Temperature Resilience: Can withstand water temperatures up to 90°C, making it compatible with any heat pump.

Designed for the tightest spaces

The iStop PLUS is perfect for modern, space-constrained heat pump installations. Its innovative design, featuring an off-axis sensor configuration, enables installation even in the most restricted spaces, catering to the diverse needs of modern installations. Furthermore, the iStop® PLUS has been designed to allow for a pair of valves to be installed vertically in parallel, meaning that installers can seamlessly install valve pairs without the need for minimum spacing.


iStop PLUS valves installed vertically in parallel.


Less space is also required for drainage, making it compatible with self-contained heat pumps that have bottom pipe connections. This flexibility not only simplifies the installation process but also optimises space usage.

Reliability and performance

Engineered to respond swiftly to changes in water temperature, the iStop PLUS ensures reliable performance and enhances system confidence. With this, the new anti-freeze valve is engineered to withstand high water temperatures of up to 90 °C. This durability allows the valve to operate with any heat pump and underscores Altecnic’s commitment to delivering products of high quality and performance.

A word from Altecnic’s Managing Director

Gary Perry, Managing Director at Altecnic, highlights the significance of this new product:

“With the iStop PLUS, we are addressing the evolving needs of modern heat pump installations. Its compact size and ability to function in restricted spaces offer unparalleled flexibility and ease of use.

“At Altecnic, we are committed to innovating high-quality solutions that meet and exceed customer expectations, keeping them ahead in the industry as we move towards Net-Zero solutions.”

Learn more

For more information about the new iStop PLUS, visit Altecnic’s website.

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