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1. General information
PLEASE LEAVE THIS MANUAL WITH THE OSO UNIT AFTER INSTALLATION.
PLEASE READ THIS MANUAL BEFORE INSTALLATION AND LEAVE UNDER THE CYLINDER TOP LID. THE
MANUAL AND ATTACHED LOGBOOK SERVE AS THE CYLINDER GUARANTEE.
Thank-you for purchasing the Delta Coil unvented hot water cylinder.
Delta is an A rated unvented hot water cylinder in all capacities 120 – 300 litres. Its energy efficiency as defined by
standing heat losses is the best in its class and will save the householder significant energy costs over the lifetime
of the cylinder.
This manual gives detailed advice for installation and should be read carefully prior to fitting any unvented unit.
OSO Delta Coil cylinders are not suitable for gravity fed primary systems. In known hard water regions, precautions
should be taken to prevent limescale formation in hot water cylinders, in accordance with Building Regulation Part
L, Domestic Heating Compliance Guide.
This OSO cylinder must be installed by a competent person and be installed in compliance with the OSO Installa
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tion and Maintenance Instructions, all current legislation, codes of practice and regulations governing the installa
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tion of unvented hot water cylinders in force at the date of installation.
1.1 Health and Safety regulations
Handling Operations Regulations 1992 defines manual handling as: “any transporting or supporting of a load (in
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cluding the lifting, putting down, pushing, pulling, carrying or moving thereof) by hand or bodily force” The Regula
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tions set no specific requirements such as weight limits. However common sense still has to be used based on
an ergonomic approach for each individual. The Delta Coil should be transported and stored in a vertical position.
1.2 Siting the Delta Coil
There are few restrictions on the siting of the OSO Delta Coil, however it should not be sited anywhere open to
frost attack. The unit should be placed on a stable flat surface capable of withstanding the weight of the cylinder
when full (see technical data on page 10) and access must be allowed for maintenance purposes. If wall mounted
with an OSO wall bracket, the wall should be capable of withstanding the forces generated by the weight of the full
cylinder. Provision should also be allowed for the routing of the discharge pipe away from the cylinder to an outside
point according to building regulation G3. (See page 9).
1.3 Component Check list
Components supplied with the unit in a separate accessory kit for site fitting:
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Multibloc valve, includes pressure reducing valve, line strainer, balanced cold water take off, (for shower or
bidet only) check and expansion valve.
• Tundish
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3/4’’ x 22mm Elbow / Drain Cock
• Motorised valve
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Expansion vessel.
1.4 Components factory fitted
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Immersion heater
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Thermostats / thermal cut-out
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Temperature and pressure relief valve.
1.5 Documentation supplied
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Installation manual & log book
1.6 Supply requirements
An uninterrupted 22mm cold water mains supply is recommended, however if only a 15mm supply is available,
this may be used provided there is sufficient flow rate available, a minimum standing pressure of 2.5 bar and a
flow rate of 20 litres per minute with a 1bar dynamic pressure is recommended. The cylinder will operate at lower
pressures and flow rates however the performance will becompromised. The OSO unvented unit is designed for
use with supply pressure up to 10 bar. For pressures over 10 bar anadditional pressure reducing valve must be
fitted in the supply pipe to the unit.
1.7 Expansion vessels
The vessel accommodates expanded water when the cylinder is heated and prevents the cylinder reaching its
maximum working pressure.
1.8 Compatible fittings and components
All thermostatically controlled boilers are compatible with indirect OSO cylinders.
1.9 Non-compatible products.
Solid fuel boilers, wood burning stoves and other non-thermostatically controlled heat sources must not be used
