Richard Bateman at RWC UK looks at how thermal balancing valves help minimise water waste in larger buildings, as the pressure grows to save resources
Wasting water is a particular problem in big buildings that use recirculating hot water systems that haven’t been designed or installed correctly, such as hotels and leisure centres. From taps being left on too long, to boilers needing to work harder than necessary, thousands of litres of water – and the associated energy needed to heat it – might be wasted from just one building.
Clearly there’s an economic cost, but this kind of wastefulness contributes to the very real issues around our global climate emergency. The good news is that a lot of this waste can be reduced through intelligent use of the right valves. Even if we can’t control what every single occupant is doing, clever design of the plumbing system can make a big difference.
Bringing balance
In commercial and healthcare buildings, hundreds of people rely on instant hot water, for handwashing, showering or cleaning. It is vital that the supply delivers efficiency, so the the system doesn’t have to work harder than needs be to achieve the required temperature at the furthest reaches of the system.
The use of thermal balancing valves (TBVs) is essential to prevent this. TBVs use a thermostatic element that works against a spring to adjust the flow rate of the hot water through the valve, depending on its set temperature. As the temperature rises through the network the valve begins to restrict to maintain this set temperature.
For safety, the valve is designed to never shut down completely, even in the event of failure.
Let’s first look at how TBVs work from a safety perspective. In larger properties, where the occupants and users may be vulnerable – like hospitals – Legionella thermal flushing is common. This is a process where the temperature of the water within pipework is raised to a disinfecting temperature that can be more than 85°C, and drained from all serving outlets. Once this process has been completed, the system temperature is lowered. Often thermal balancing valves are manually opened to allow circulation through the valve without restriction.
Valves are available however that need no manual adjustment to allow flow – simply recognising that the inlet temperature is above 70°C, and opening automatically. Hundreds of TBVs are often required for these larger systems so the time and hassle saved by this automatic feature is key.
Sustainability
As well as making hot water systems safer for use, TBVs also bring energy efficiencies by putting less stress on the boiler. If the system is thermally balanced, the users can access hot water as soon as they open the tap. However, if the system isn’t properly balanced, users have to wait for hot water to reach the outlet by keeping the tap turned on, which leads to unnecessary water wastage.
TBVs are designed to balance the entire hot water network, therefore individual valves should be installed at every hot water draw off area. For example, if there are 100 rooms in a hotel, a TBV should be installed for each room. This will ensure a constant temperature across the circulating loop no matter where you are in the building.
Think big
The 2021 National Infrastructure and Construction Pipeline sets out nearly £650bn of public and private investment that will transform people’s lives for decades to come. From the 10-year school rebuilding programme to the creation of 40 new hospitals by 2030, as well as many more projects in between, big buildings are a key focal point of the UK’s construction strategy. At the same time, the UK is on the pathway to achieve net zero carbon by 2050.
These are big ambitions, and clearly the construction and environmental targets are linked. So we must all think big in how to help achieve water efficiency. Using the right blend of pipes, valves and fittings, systems can not only conserve water but also be much more energy efficient in future.
Richard Bateman is product marketing manager at RWC UK