Mr. Eamonn Smyth:

Zoning is in part L of the building regulations and is to prevent energy loss by not heating areas people do not want to heat. Most systems are now zoned with a manifold system and are based on thermostats in various areas which are turned on or off automatically depending on timeframes. All of the systems are closed, so there is no risk of getting close to the water involved and the temperature is always above 60° Celsius and legionella is killed automatically in seconds at 60° Celsius. There is no risk in any of them. Legionella must be inhaled through an airspray or aerosol, so shower heads have been a problem historically and there are issues in this regard are present, but not in heating systems.

All of the various heating systems, in particular oil and gas, are based on normal hot water heating systems and the back boiler systems are the same. Air to water heat pumps rely on a heat transfer and once this heat transfer has occurred it is the same type of system from a distribution point of view.