With regard to heating systems do single pipe systems have to be replaced with the twin pipe systems?
A. When a boiler is replaced the system must comply with Part L. In practical terms meeting the minimum requirements given in the Domestic Heating Compliance Guide* will achieve this. It covers the water circulation and control requirements of space heating and hot water systems. This is usually interpreted as: – Upgrade to fully pumped from gravity circulation if required – Install time controls – Install interlock (room thermostat AND cylinder thermostat + motorised valve(s) for a regular boiler system and room thermostat for a combination boiler system) – Install bypass where necessary Whilst it is preferable to use a two-pipe system, there are no specific requirements in the Building Regulations that a one-pipe system should be upgraded when replacing a boiler. A condensing boiler can usually be connected to a one-pipe system, unless the boiler manufacturers’ instructions say otherwise. A two-pipe system would normally be necessary if it were also intended to install thermostatic r
