The importance of PRVs in multi-occupancy plumbing

It is no secret that multi-occupancy housing is becoming increasingly commonplace across the UK. Whether it is older buildings being converted into flats, brand-new apartment blocks being built, buildings of multiple occupancy are particularly popular in cities where housing is in high demand.

In Q3 of 2024, apartments accounted for 15% of new home registrations – up from 12% just three years earlier – according to NHBC figures. Figures also show an increase of 10% in Houses of Multiple Occupancy (HMOs), demonstrating how existing buildings are being repurposed to cater for today’s housing needs.

This growth represents significant opportunity for the plumbing and heating industry to ensure multi-occupancy buildings are fit for purpose, delivring the operational efficiency and occupant comfort required of homes today.

That’s why, in this blog, we’ll explore:

• the role of valves in a well-planned multi-occupancy plumbing system
• PRVs as a solution
• how building designers, specifiers and installers can create effective systems

More dwellings – and more people – in multi-occupancy buildings inevitably means one thing – more complex plumbing systems. That’s because each apartment within a building must draw off the same water system, while still delivering the performance and convenience expected by occupants.

Water control valves are essential here, balancing user needs with operational efficiency. The right valves installed in the right places across the system will ensure every outlet and appliance is able to draw on the water pressure that’s required to deliver.

In larger buildings like apartments, pumps are used to generate higher pressures so that adequate pressure reaches the furthest parts of the system. The closer the apartment is to this pump system, the risk of high pressure damage is increased without the correct control and protection in place. Installing PRVs in these applications ensures the safety of the occupants, but also the performance and longevity of the system.

Pressure Reducing Valves are essential in multi-occupancy plumbing systems. As the name suggests, they are engineered to manage the pressure of water within a building’s plumbing system – by controlling the pressure and carefully maintaining it to deliver adequate pressure where it’s needed.

This is achieved by reducing the pressure within the system at the apartment, which allows the water to still be pumped at high pressures through the network but reduced to a useable and safe working pressure at the point of entry to the dwelling. Alongside supporting the efficient performance of other associated valves, fixtures and appliances, managing water pressure effectively will also enhance efficiency as reducing the pressure not only stabilises the supply, but also reduces the flow rate and consumption to the apartment.

The concept of staging the reduction of pressure is particularly impactful when it comes to safety and the longevity of the system. Reducing an extremely high pressure to a low pressure can result in valve throttling and cavitation. This can cause damage to the valve over time and often leads to a lot of noise as the components wear under these conditions. Therefore, installing a larger secondary PRV as protection to an entire floor, and setting this to a higher pressure to gradually reduce the pressure, is advised. For example, if the supply pumps are set to 12 bar, and the required pressure for each apartment is 1 bar, using this larger valve - set to, for example, 5 bar - will ensure that cavitation doesn’t occur. The secondary PRV also acts as a safety in the event of a failure at an individual apartment, essentially controlling the pressure, but also acting as a safeguard to other associated valves.

For system specifiers, there are a few important steps to follow when it comes to selecting the most appropriate PRV for the job. This includes developing a complete understanding of the building in question, including the operational system pressure, set outlet pressure required, as well as the flow rate demand.

From here, it is possible to choose the correct PRVs for the job. The 315i PRV from Reliance Valves is commonly used in multi-occupancy buildings thanks to its ability to adjust between 1.5 and 6.0 bar and its suitability for hot and cold systems. The valve’s compact design also supports straightforward installation and makes maintenance easy, with all working components contained within the one-piece cartridge.

With multi-occupancy homes becoming an ever-greater part of the UK’s housing mix, it is essential for plumbing and heating professionals to have the knowledge and skills to deliver reliable, safe and efficient plumbing systems. Additionally, access to high-quality solutions and resources will help to meet the evolving needs of these complex systems.