A mains pressure hot water cylinder  provides, mains pressure hot water service direct from the main.

It achieves this by operating in the reverse way to the conventional system.

The unit is heated up usually directly from the boiler, into the thermal heat store.  This is then used to instantaneously heat mains fed cold water passing through a heat exchanger coil or tank.

The level of insulation on these units is very high, leading to minimal heat loss.  Used in conjunction with a condensing boiler, the system becomes even more efficient.

These units are normally used where the demand for hot water is likely to be quite high. The combination of these units in dwellings with showers can result in a higher level of shower performance.