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Is insulating Preheated Cold Water Main pipework a mandatory or recommended practice for WWHRS installation?
In order to ensure maximum impact from the WWHRS system, Recoup does recommend insulating the pre-heated CWM feed wherever possible to reduce thermal loss. However, this is not mandatory for either SAP compliance or Building Regulations compliance in new-build dwellings, and any requirement to insulate preheated pipework is at the discretion of the developer or specifer, and is likely to reflect or extend from, their existing DHW pipework insulation strategy.
Depending on the specified installation method (System A, B or C) preheated water may be fed to either the shower, the hot water source, or both. In the image below, preheated CWM pipework is denoted in 'orange'.
Specifying and installing effective pipe insulation is key for energy efficiency, safety and cost savings in UK buildings. Organizations like BRE, BSI and CIBSE develop the standards needed to drive insulation material and installation quality.
Most standards around insulation pipework are concerned with DHW pipe work, rather than CWM (or preheated CWM) pipework, when that CWM pipework is located within the building's heated envelope. Arguably it is best precative to insulate all hot and cold pipework to prevent heat loss / heat gain within the envelope, however, this level of insulation is not currently mandatory
The key standards are Building Regulations Part L (Conservation of
fuel and power), EN 12828, PAS 67, BS 5422, BS 5970, and HSE guidance on preventing corrosion under insulation. Part-G (Sanitation, hot water safety
and water efficiency) should also be considered, as well as any relevant HBF guidance. Compliance futureproofs buildings against tighter regulations. Workmanship certification and oversight ensure insulation performs to its potential.
Approved Document L Volume 1, 2021 edition:
With insulation being a vital tool in UK carbon reduction efforts, its standards will continue advancing. Staying current on the latest best practices, codes and standards allows industry professionals to maximize the benefits of pipe insulation.