Unvented Design - Potterton iHE 100 Installation & Servicing Instructions Manual

2.5 UNVENTED DESIGN

Unvented Systems should only be
fi tted by an Approved Installer
When using the Heater on an unvented hot water
storage system, the Unvented System Kit, part
number B328, available from the manufacturer
must be fi tted. See section 4.4
When used in an unvented system, the Heater will
supply hot water at a maximum of 3.5 bar or at the
pressure available at the mains feed if this is lower.
During conditions of no-fl ow, system pressure may
rise to a maximum of 6 bar, whilst the burner is
operating. When testing the system, it is recom-
mended that a maximum test pressure
used.
For the hot water supply, a 25 litre expansion
vessel is suitable for the stored volume of all mod-
els of the Heater and an average pipework system.
For systems with larger pipe volumes or additional
storage, expansion vessels with greater capacity
are availaible.
Assemble the components of the unvented system
kit as shown in Fig 2.4
For the Central Heating supply the expansion ve-
sel must comply with BS4814 and must be sized on
the basis of total system volume and initial charge
pressure. Initial minimum charge should not be less
than 0.5 bar and must take into account static head
and specifi cation of any pressurising equipment.
iHE
of 7 bar is
Hot
Water
Te m p e r a t u r e &
P r e s s u r e R e l i e f
Valve
Cold Water Inlet of Water
Check Valve
Expansion Valve
Tundish
10
When assembling the Pressure Reducing
Valve and Double Non-Return Valve,
ensure that the fl ow arrows marked on the
components are pointing in the direction of
fl ow, that is towards the Heater.
The relief valves fi tted to this appliance must not
be used for any other purpose. No fi tting should
be installed between the expansion valve and the
cylinder.
The cold water for services may be drawn from the
22mm compression port up strea of the Pressure
Reducing Valve. The water pressure at this point
will be similar to that available at the hot water
outlet of the water heater.
If higher fl ow rates are required for the cold water
services, a suitable tee fi tting should be fi tted to
the pipework, upstream of the Pressure Reducing
Valve.
The pipework fi tted to the tundish outlet should be
at least 28mm diameter, made of metal and should
be terminated at a suitable drain (see Building
Regulations Approved Document G3).
All fi ttings and materials supplying water to the
storage vessel must be suitable for use with drink-
ing water and listed in the current Water Research
Centre "Materials and Fittings Directory".
Installation of unvented hot storage water systems
must comply with Part G of Schedule 1 of the Build-
ing Regulations.
Expansion
Vessel
Wall Bracket
Assembly
Pressure Reducing
Valve/Strainer
Balanced Cold Water
Take-off (if required)
Hose Assembly
Cold Water Feed
Fig 2.4
GB/IE