Installation manual

31 ©ESP Ltd. Sept 2008
Installation, Commissioning and Maintenance of Unvented Systems
Although the basic principles are similar, the installation, commissioning and
maintenance of an Unvented System must be in strict accordance with the rele-
vant manufacturer‟s instructions and, all installations must be carried out by a
“competent person” approved to install Unvented Systems.
As the dominant supplier and, pioneers in the development of controls for
Unvented Systems, the Reliance range of controls incorporate unique features
to ensure superior performance; ease of installation; long, trouble-free service
and ease of maintenance and replacement.
In this part of the Guide, we look at the different controls used on the majority
of Unvented Systems in the UK. These controls fall into two specific groups -
Functional Controls and Safety Controls.
Functional Controls
Required to protect the mains water supply from contamination and the un-
vented unit from over pressure, these controls consist of the following compo-
nents:-
• Line Strainer - filters debris from the water supply to reduce the risk of
damage to downstream controls.
• Pressure Reducing Valve - reduces the mains water pressure to the specified
cold working pressure of the unit.
• Single Check Valve - prevents contamination of the mains water supply from
backflow and, crossflow between hot and cold distribution pipes.
• Expansion Valve - protects unit from over pressure caused by failure of pres-
sure reducing valve, failure of expansion vessel or loss of internal air bubble.
Originally supplied as separate components, Reliance have developed and
engineered these controls to form a one piece or two piece Inlet Control
Group for units requiring DN20 Nominal size controls and, a three piece Inlet
Control Group for units requiring DN25 size controls.Inlet Control Group -
One Piece (Multibloc).
Originally developed for use on Bubble-To units - there is no provision for an
integral expansion vessel connection - this control is now found on all types
of Unvented Systems and offers the following features.
Inlet Control Group - One Piece (Multibloc)
Originally developed for use on “Bubble-Top” units
- there is no provision for an integral expansion ves-
sel connection - this control is now found on many
types of Unvented Systems and offers the following
features.
• Integral coaxial stainless steel strainer
• Drop tight balanced seat Pressure Reducing Valve
- very stable under fluctuating inlet pressure con-
ditions.
• Unique one piece Pressure Reducing Cartridge
with noise reduction comb - facilitates ease of
maintenance, reduces system noise further and
prevents cavitation.
• Balanced cold water connection - equal pressures to mixer taps/showers.
• Unique stainless steel seat Expansion Valve - dramatically reduces prema-
ture failure from seat erosion - Particularly in hard water areas.
• Superior flow rates - up to 55 l/m.
• Multi-orientational - installation flexibility.
UNVENTED HOT WATER STORAGE SYSTEMS AND CONTROLS