The Glowworm Swiftflow is a Combination boiler that only produces hot water on demand (ie there is no hot water storage tank).
When a hot water tap (or your shower) is turned on a sensor inside the boiler detects the water flow and brings the boiler on. As soon as the flow stops the boiler will go out again.
Basicaly you are only heating the water you are using at the time you are using it.
I hope this helps
Robin S
August 2008