Unvented Hot Water

How the unvented system works

The basic difference between the high pressure unvented systems and a traditional low pressure vented system is that we no longer require the cold water storage cistern, open vent pipe or cold feed pipe.

Instead, the unvented unit is fed direct from the mains cold water supply via an inlet. Hot water drawn from the unit is then replenished from the mains supply.

As water expands when heated and (as the name implies) there is no vent pipe, the expanded water within the system is accommodated by either an external expansion vessel or, in the case of bubble-top units, an internal air bubble within the unit which is generated when the system is commissioned.

The significant benefits to be gained from the installation of an unvented hot water storage system are high water pressure at all outlets, a well designed system can provide a maximum of up to 72 litres per minute.

Householder BenefIts

• Superior performance - ensures constant high flow rates at all outlets and allows rapid filling of baths.

• Balanced pressures - far wider choice of taps and showers can be used.

• Reduces hydraulic noise in system - no filling of cold water storage cistern.

• Eliminates risk of freezing and burst pipes in roof space.

• Eliminates risk of contamination - no cold water storage cistern in roof space.

• Frees roof space - can be utilised for loft conversions.

• Energy efficient - reduces fuel costs.