Specifying plumbing systems for safety and efficiency

When it comes to specifying plumbing systems for safety and efficiency, regulatory requirements have a direct impact on component selection. One of the key regulations that specifiers need to follow is Part G of the Building Regulations, which is geared towards sanitation, hot water safety and water efficiency. 

For specifiers, this brings several challenges to the fore. Firstly, how to ensure water safety at every point of use across a system, overcoming potential issues such as backflow. Secondly, where water efficiency is concerned, specifiers need to create systems that optimise water usage and support users to reduce consumption – all while meeting every user demand. 

In this blog, we’ll take a look at what this means in practice – and explore some of the solutions that are vital to success. 

In both unvented and pressurised heating systems, managing pressure caused by expansion as water temperatures fluctuate is key to creating safe systems that can perform over the long-term. 

To do this effectively, the use of expansion vessels is important. Expansion vessels are split into two sections – one side that holds water and one side containing air. As the volume of water expands as temperatures increase, the vessel accommodates the increased volume, thereby relieving pressure within a system, mitigating against backflow. This sometimes occurs due to the thermal expansion and avoiding potential damage that could be caused if there isn’t the necessary prevention and safety devices in place. This avoids potential damage that could be caused if the pressure has no outlet. 

When it comes to specifying plumbing systems expansion vessels, there are a couple of key considerations that should be made. 

Firstly, getting the sizing of the expansion vessel correct will form the foundations of success for the complete system. In practice, this creates adequate thermal expansion for the system which, if incorrectly sized, could result in leaks and blowouts in the event of increased system pressure. Not only would this have the potential to cause damage to the system and property, but it could also compromise user safety. 

Getting the sizing of the expansion vessel correct requires an understanding of the complete system, including factors such as the volume of water within the boiler, the amount of radiators being supplied, the pipework that form the system, and the system pressure when cold. 

Specifying an expansion vessel provides a layer of protection, preventing pressure build-up within the system. 

After sizing, the location of the expansion vessel becomes critical. In heating applications, the vessel should be located in the return leg, close to the heat source for maximum effectiveness. Boiler manufacturers integrate these vessels within their unit but for older hot water systems, an additional vessel is required as well as the vessel installation on the cold supply to the cylinder. This ensures protection from ambient temperature. Vessels protect the components and ensure the system operates effectively and efficiently without the risk of water waste. This protects the vessel from prolonged exposure to high temperatures which can damage components and compromise its ability to perform effectively. 

Water efficiency is a further consideration when specifying plumbing systems. 

Managing water pressure effectively within a plumbing system ensures that every outlet has the water pressure needed to perform as required. When pressure is too high, excess strain is placed on the system which can cause damage over time. When pressure is too low, outlets may struggle to deliver effectively – whether that’s slow supply at the tap, or compromised performance of appliances. 

From an efficiency perspective – which is now a key part of plumbing design due to regulatory shifts – managing water pressure can directly impact levels of consumption. When specified correctly, plumbing systems will effectively feed outlets and appliances, without compromising on user needs. 

There is an added benefit to achieving optimum water pressure, too. Plumbing systems that have excess pressure can be noisy, which compromises comfort for end users who may hear noises from pipework – something known as water hammer. 

The specification of shock arrestors can mitigate against this noise. As water hammer is caused by pressure surges in the water supply which create sudden stops or a change of flow, controlling this with solutions such as shock arrestors can be advantageous. 

The Potable Water Shock Arrestor from Reliance Valves is a compact vessel which can be installed close to appliances and fixtures to control water pressure and eliminate water hammer.