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4. Description of the product
4.1 General description
This product is a purpose designed unvented water
heater. The unit has a stainless steel inner vessel, which
ensures an excellent standard of corrosion resistance.
The outer casing is a combination of resilient
thermoplastic mouldings and pre-coated steel. All
products are insulated with CFC free polyurethane
foam to give good heat loss protection.
The unit is supplied complete with all the necessary
safety and control devices needed to allow connection
to the cold water mains. All these components are
preset and should not be tampered with.
4.2 Operation principle
The unvented cylinder is used to heat and store hot
water for use in domestic intallations.
Depending on the model the water can be heated
directly using Immersion heater(s) or indirectly through
a coil in the unit using an indirect heat source.
4.3 Main connections
See Figures 7 : Main Schematic on page 13
4.4 Standard delivery
The delivery includes:
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Cylinder
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Factory fitted immersion heater(s) and thermal
controls
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Factory fitted Temperature and Pressure Relief
Valve (set at 90ºC / 1 Mpa (10bar))
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Factory fitted indirect thermostat and thermal cut-
out
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Literature pack
Instructions (inc benchmark commissioning
checklist & service record)
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Cold water control pack
Combination valve (inc pressure reducing valve,
pressure relief valve and check valve)
Expansion vessel and mounting bracket
Tundish
Nuts & Olives
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2 port zone valve (indirect only)
5. Before installation
WARNING
Installation of the appliance must be carried
out by a qualified engineer in accordance
with prevailing and national regulations as
listed below.
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Building Regulations G3
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The Building Standards (Scotland)
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The Building Regulations (Northern
Ireland)
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I.E.E Electrical Regs
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UK Water Regulations
5.1 Installation regulations
5.2 Installation requirements
Water supply
In an unvented system the pressure and flowrate is
directly related to the incoming water supply. For this
reason it is recommended that the maximum water
demand is assessed and the water supply checked to
ensure this demand can be satisfactorily met.
`
We suggest the minimum supply requirements
should be 0.15MPa (1.5 bar) pressure and 20 litres
per minute flow rate. However, at these values
outlet flow rates may be poor if several outlets are
used simultaneously.
`
A 22mm cold water supply is recommended,
however, if a smaller supply exists, which provides
sufficient flow, this may be used (although more
flow noise may be experienced).
`
The higher the available pressure and flow rate the
better the system performance.
`
See table 1 & 3 on pages 5 & 6 for cylinder
operating pressures. This is controlled by the cold
water combination valve assembly.
`
The water supply must be of wholesome water
quality (Fluid Category 1 as defined by the Water
Supply Regulations 1999).
Outlet/terminal fittings (taps, etc.)
`
The cylinder can be used with most types of
terminal fittings.
`
Outlets situated higher than the cylinder will give
outlet pressures lower than that at the heater, a
10m height difference will result in a 1 bar pressure
reduction at the outlet.
`
All fittings, pipework and connections must have
a rated pressure of at least 6 bar (dependant on
cylinder being fitted) at 80°C.
`
It is advantageous in many mixer showers to have
a balanced hot and cold water supply, in these
instantaces a balanced cold water connection
should be placed between the cold water
combination valve and the cylinder.
