Fabdec’s 3S Boiler Technology Explained

Fabdec’s 3S Boiler Technology Explained

Stuart Doggrell, National Sales Manager, Fabdec, explains how the company’s 3S technology could be about to take the water heating industry by storm.

Despite being pioneers in the water heating industry for many years, you may still not be aware of UK manufacturer Fabdec. This could change very soon though thanks to a new technology which we hope will be a game-changer for builders and installers.

At EcoBuild 2015, Fabdec launched the Excelsior i with 3S Technology, a unique innovation in the world of unvented water heating which saves on time, space and money.

So what is 3S Technology, what makes it stand out, and how does it apply in an everyday domestic setting?

excelsiorgroupBefore 1986 it was prohibited in the UK to heat water in a pressurised closed cylinder because of the risk of explosions due to a build-up of pressure.

The change in legislation was accompanied by a set of rules and regulation to ensure the security and the safety of running this system. In accordance with BS 7206:1990, to accommodate for the expansion of the water as it is heated inside the water tank, an external pressurised expansion vessel would need to be installed in the piping system.

While this became common practice, Fabdec decided to look into developing internal expansion devices, which would provide a volume of air above the water level inside the cylinder.

From our manufacturing site and head office in Ellesmere, Shropshire, we developed a pioneering floating baffle, which would sit on the water surface and reduce the exposure of air to water to a minimum. This was an innovative technology that enjoyed huge success and is still used extensively throughout the industry today.

However, we understood that while this was an achievement in itself, it only minimises the issue and does not eradicate it. Using a baffle results in a short, medium or longer-term retention of the internal air expansion gap. The air gap or ‘bubble’ will need to be re-charged, which may or may not be frequent dependent on the conditions of use.

Ultimately, the system would still be liable to wear-and-tear and require maintenance.

So, in the early 2000s we started looking at ways to improve the performance of our original patented floating baffle, to see if we could create a totally self-sustaining system.


One idea we trialled was installing a device on the inlet valve which would follow the Venturi effect, so named after Italian physicist Giovanni Battista Venturi (1746-1822).

This is the reduction in pressure that results when a fluid flows through a constricted section of pipe with no discernible restriction to flow rate.

In the process, a fluid’s velocity must increase as it passes through a constriction in accordance with the principle of continuity, while its static pressure must decrease. Any gain in kinetic energy a fluid may accrue due to its increased velocity through a constriction is balanced by a drop in pressure.

It is the mixing of liquid with air – or more specifically the induction of air bubbles into the liquid – that makes the patented ‘Self-Sustaining System’ 3S Technology unique, with the system now able to maintain the internal air gap pic2as hot water is drawn off further upstream in typical usage.

As it replenishes the internal expansion device permanently, there is no need for recharging or regular servicing.

The end product was the Excelsior i range of water heaters, which differ from every other unvented vessel currently on the market.

Firstly, the 3S Technology and automatic replenishment of the air gap saves time and money – there are no internal, moving parts in the cylinder and once the Venturi valve is installed, no additional parts are required. The epitome of fit-and-forget technology, 3S will give self-builders and developers, landlords and installers confidence that they will not be regularly required to check for wear and tear or be called out to solve problems.

pic3The absence of an external expansion vessel also means the tank can fit into more compact installation spaces, giving builders and installers much more flexibility on where to place the heater, whether it for a new build or renovation project.

Fabdec currently produces a range of sizes in the Excelsior i range, from 80-litre up to 500-litre which are readily available. Tailored to site specification we are still able to provide dedicated design engineers and short lead-times due to locating the entire operation under one roof.

For more information click here.

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