The OSO 18 series is a bespoke water jacket design unvented cylinder available from 500 to 10,000 litres. The 18 series is manufactured in a double convex fashion. The cylinder can be supplied in both direct and indirect heating formats.
 
The cylinder is of particular use in hard water areas as the primary heating water circulates through the outer jacket, meaning that scale accumulation will be restricted compared to a conventional coil heat exchanger. Direct 18 series cylinders have the immersion heaters located in the outer water jacket. As this water is inert, lime scale accumulation on the elements is eliminated.
 
The domestic hot water is heated evenly from the base and the sides meanng that there is no “dead zone” in the base of the cylinder where water is permanently cooler. This eliminates the need for destratification pumps and enhances the use of the cylinder for public and other large buildings.
 
18 series cylinders can be supplied with stainless steel (18R) or copper lined steel (18S) construction. 18R are available up to 1,000 litres, whilst 18S are available to 10,000 litres.
 
Insulation is by CFC free glass wool at a thickness of 100mm. The outer casing is blue powder coated painted steel.
 
Secondary water expansion can be accommodated in a self generated air gap or by a separate expansion vessel suitable for potable water.
 
The 18 series can be supplied with a blending valve to allow high temperature water storage to increase the amount of usable hot water from a given capacity cylinder.
 
The inner vessel has a maximum working pressure of 10 bar. All seams are fusion welded. The outer primary jacket has a maximum working pressure of 4 bar.
 
All OSO commercial calorifiers, including the 18 series are manufactured to individual specification. Extras such as inspection manholes, extra or larger bosses and connection and pressure control valves are available on request.
 
OSO commercial cylinders can also be supplied as vented products.