Zoned heating systems and TRVs

Dan Love, head of Commercial at Polypipe Building Products, looks how the new Building Regulations requirements on energy efficiency will have an impact on the way the heating systems in homes are set up.

The industry has been in a 12-month grace period for updates to Part L of the Building Regulations covering energy efficiency. But that’s about to draw to a close.

The major updates to the regulations are designed reduce carbon emissions in new and existing homes by 31 per cent, as a precursor to the even more ambitious Future Homes Standard, which is due to come into force in 2025.

The Future Homes Standard aims to ensure that, on average, new homes produce at least 75 per cent less CO2 than a home that has been built to current energy efficiency requirements, and will mean that all future homes are net zero-ready and will not need retrofitting.

The changes

One major update is that new heating systems in homes with a floor area of 150m2 or greater will now need a minimum of two independently controlled zones, with each zone or room requiring its own smart or thermostatic controls.

Splitting the system into zones that can be controlled independently means that the levels of heat in each area can be controlled by users: they can choose to heat only the parts of the property that are in use.

For example, if someone is in the living room downstairs, they can turn off the heat in a bedroom. By turning the heating off in any rooms where it is not required, less energy will be used, resulting in less wasted heat, lower carbon emissions and lower energy bills.

For all hot water stores, a timer is required for heating and hot water so that they can be controlled independently of the space heating circuit. The pump now needs to turn off automatically when heat is not required. This means that the controls should be wired to ensure that the heating appliance and pump are switched off when there is no demand for heating or hot water.

The solutions

One of the most logical solutions to zoning a heating system is to install underfloor heating (UFH) because it is naturally designed and installed into zones. UFH manifolds can control multiple zones at once, which enables each to be warmed to a different temperature, depending on the user’s requirements. UFH is now simple to install in retrofit projects without any complications such as shaving down doors, thanks to the introduction of low-profile systems.

UFH covers a greater surface area, which means it can run at lower temperatures of 33°C-55°C rather than 75°C, and therefore places significantly less demand on energy sources. This helps to comply with the requirement that the maximum flow temperature for newly installed heating systems should be 55°C.

These requirements can still be achieved when installing traditional heating systems, through a thermostat or thermostatic radiator valves (TRVs) on all heat emitters in the rooms that do not have a thermostat.

TRVs control the flow of hot water through the radiator to which they are fitted. If the room is warmer than the setting on the TRV, the valve will close a little, reducing the volume of hot water flowing into the radiator. Similarly, if the room temperature is lower than the TRV setting, the valve will open, increasing the flow of hot water. TRVs can be adjusted to different settings between fully open and fully closed, with lower settings reducing the volume of hot water flowing and so using less energy.

Compliance is key

It’s important to note that the Part L updates don’t only affect the heating systems in new-builds: they cover refurbishment and retrofit projects as well. This means that the regulations will have an impact on all projects – both new-builds and existing homes. ■ www.polypipebpfuturehomes. com