Turn off hot water preheat#
On a combi-boiler, “hot water preheat” keeps a bit of water warm at all times in case you want to wash your hands. It makes the water in your tap run hot faster than it would without it, although if it’s a long way between the boiler and the tap you’ll never notice the difference.
one example of this control - every boiler is a little different
In houses, hot water preheat typically accounts for 5-10% of the gas bill. In community buildings, hot water preheat is particularly wasteful because it’s on 24/7, but most community buildings don’t have anyone in overnight. If your building users really can’t tolerate the delay, on some boilers a more adventurous electrician can tie it to the heating time switch so that the water only preheats when people are in.
More information
Turn off the preheat on your Worcester combi boiler - the same website has instructions for many boilers