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2.3 HOW THE APPLIANCE
WORKS
2. INSTALLATION
These regulations (byelaws in Scotland) ensure a good supply of
wholesome water, and that only approved materials, pipes and fittings are
used to convey water.
These are a statutory document and take priority over all other regulations
and recommendations. The installation of an unvented hot water storage
cylinder is classified as a “Controlled Service” and Regulation G3 applies. To
meet the requirements of the Regulation, installation of an unvented system
should be undertaken by a “competent installer”.
All installations of unvented hot water storage systems having a capacity of
more than 15 litres should be notified to the relevant Local Authority by
means of building notice or by the submission of full plans. It is important to
note that it is a criminal offense to install an unvented hot water storage
system without notifying the Local Authority. The installation of the unvented
cylinder and hot water system must comply with BS 6700 and the HSE
Legionella Code of Practice.
The immersion heater(s) are controlled through a thermostat which senses
the water temperature. The operating temperature can be pre-set by
adjusting the spindle in the head of the thermostat. In addition to the
thermostat there is a thermal cut-out incorporated if the thermostat fails and
the water temperature rises too high. Once the cut-out operates it can only
be re-set manually after the fault has been rectified.
Indirect models have dual thermal controls. In addition to the above there is
a separate cylinder thermostat and thermal cut-out for controlling the indirect
circuit. Again the thermal cut-out operates if the cylinder thermostat fails, by
disconnecting the live feed (call for hot water) from the programmer.
Classico (STD/STI) models have magnesium anodes provided to prevent
corrosion of the cylinder tank.
All
High Capacity (STD/STI) 500 litre models, Wall-hung (ST) units and the
Contract (STD/STI) Floor-standing models utilise the ProTech anti-corrosion
system (electronic anode).
The factory fitted temperature & pressure relief valve at the top of the
cylinder is a safety device to back-up the thermostat(s) and thermal cut-
out(s). It works by sensing an excess in water temperature or pressure and
releasing the hot water into a discharge tundish and drain.
The cylinder will only work in the vertical position. The inlet pipe needs to
deliver cold water to the bottom of the tank. When water is heated it
expands. To accommodate this increase in volume an expansion vessel is
provided. A cold water combination valve is also provided in two pieces,
loose jointed for ease of installation. These comprise a combined line
strainer/pressure reducing valve and core non-return valve/expansion relief
valve.
The strainer prevents any debris entering the other controls. The pressure
reducer ensures the correct operation of the expansion vessel, and prevents
any damage to the control valves through too great a pressure.
The non-return valve ensures the water expansion is forced into the
e
xpansion v
essel and pre
v
ents contamination of the mains cold w
ater
supply
.
The e
xpansion relief v
alv
e will discharge e
xpanded w
ater to the
discharge tundish if the e
xpansion vessel fails.
2.1 WA
TER
REGULA
TIONS
2.2 BUILDING REGULATIONS
www.tradeplumbing.co.uk Call Sales On 08708034288
www.tradeplumbing.co.uk Call Sales On 08708034288