Benefits of oso unvented cyclinders:

Resistant Super Molybdenum     
Stainless Steel
No sacrificial anode to check or maintain
25 year cylinder guarantee
2-year guarantee on all other components, lime scale excepted
Production facility NS-ISO 9002 accredited NOW ISO 9001: 2000 and ISO 14001
BBA approved
WRAS listed
British Gas listed OSO cylinders can be included in British Gas Three Star 
Maintence schemes
NEMKO approval for all immersion heater and thermostats
CE listedFast filling baths - quiet in operation
Flow rates can be as high as 55 litres per minute at 2.1 bar
High performance mains pressure showering - no shower pump required
No cold water storage tanks required
Dry roof space removing the threat of frozen pipes and tanks
No noisy ball valves
Mains pressure at multiple outlets
Potable water to all outlets
OSO cylinder can be installed anywhere within thermal envelope af building allowing  greater flexibility of design
Copper tube is all that is needed to install an OSO cylinder
One piece cold water inlet valve assembly supplied
Immersion heaters are factory fitted and hard wired
Surface mounted cylinder thermostats are supplied factory fitted
All cylinders are factory pressure tested to 16 bar
Combined cold water feed and drain cock supplied
Minimal heat loss assured with the use of CFC free fire retardant polyurethane foam
Dedicated secondary return facility standard on all OSO cylinders