The Domestic Heating Compliance Guide, provides guidance on compliance with the Building Regulations, Part L, (Conservation of fuel and Power) amended in 2006, contains the requirement: “where the mains water hardness exceeds 200 parts per million, provisions should be made to treat the feed water to water heaters and the hot water circuit of combination boilers to reduce the rate of accumulation of limescale and consequent reduction in energy efficiency”. This inclusion followed industry representation to the CLG in recognition of the major impact from limescale on reduced energy efficiency of domestic heating appliances
