Question from Paul Brown, via e-mail:
Part 1: Can a heating system safety discharge pipe terminate in to an internal drain, provided it has a tundish within 500mm of the safety valve?
Part 2: Can the D2 section of the pipework be in polypropylene plastic?
Answer from Martyn Bridges, director of marketing and technical support at Worcester, Bosch Group:
It is common practice to terminate a heating safety discharge pipe externally to the property, however, if it is necessary to terminate internally it is always best to discuss the request with your local building control officer, so they can assess on an individual property basis. Care should always be taken when terminating the discharge so it does not cause an obstruction or risk to individuals or the property itself. Refer to manufacturers installation literature for further guidance if required.
British Standards make reference to a suitable material for the safety discharge pipe, meaning it must be able to safely withstand the temperatures of the water discharged. Metal pipe (e.g. copper) is used in the majority of these installations if not all, any other material used will need to demonstrate that it is able to withstand high temperatures and is clearly and permanently marked to identify the products performance.