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SECONDARY RETURN
On Floor-standing models a Secondary Return may be fitted. On Contract and Comfort models via the special port on the
side of the cylinder (consult the label on the face of the unit for the correct location), for 300 and 500 litre models refer to fig.
6. A Non Return Valve (not supplied) must be fitted to prevent back flow and a Bronze Pump will be needed in conjunction
with a Pipe Thermostat to circulate the hot water (both not supplied).
DISCHARGE PIPEWORK
1) The Tundish must be vertical and fitted within 500mm of the Temperature & Pressure Relief Valve and must be located
with the cylinder. The Tundish must also be in a position visible to the occupants, and positioned away from any electrical
devices. The discharge pipe from the tundish should terminate in a safe place where there is no risk to persons in the
vicinity of the discharge and to be of metal.
2) Discharge pipes from the Temperature & Pressure Relief and Expansion relief valve may be joined together.
3) The pipe diameter must be at least one pipe size larger than the nominal outlet size of the safety device unless it's total
equivalent hydraulic resistance exceeds that of a straight pipe 9m long.
I.e. Discharge pipes between 9m and 18m equivalent resistance length should be at least 2 sizes larger than the nominal
outlet size of the safety device. Between 18m and 27m at least 3 larger, and so on.
Bends must be taken into account in calculating the flow resistance.
See fig. 7 and Table 2.
4) The discharge pipe must have a vertical section of pipe at least 300m in length, below the Tundish before any elbows or
bends in the pipework.
5) The discharge pipe must be installed with a continuous fall.
6) The discharge must be visible at both the Tundish and the final point of discharge, but where this is not possible or
practically difficult; there should be clear visibility at one or other of these locations. Examples of acceptance are:
i)
Ideally below a fixed grating and above the water seal in a trapped gully.
ii)
Downward discharges at a low level; i.e. up to 100mm above external surfaces such as car parks,
hard standings, grassed areas etc. These are acceptable providing that where children may play or
otherwise come into contact with discharges, a wire cage or similar guard is positioned to prevent
contact, whilst maintaining visibility.
iii)
Discharges at high level; I.e. into a metal hopper and metal down pipe with the end of the discharge
pipe clearly visible (Tundish visible or not). Or onto a roof capable of withstanding high temperature
discharges of water 3m from any plastic guttering systems that would such a discharge (Tundish
visible).
iv)
Where a single pipe serves a number of discharges, such as in blocks of flats, the number served
should be limited to not more than 6 systems so that any installation can be traced reasonably easily.
The single common discharge pipe should be at least one pipe size large than the largest individual
discharge pipe to be connected. If unvented hot water storage systems are installed where
discharges from safety devices may not be apparent I.e. in dwellings occupied by the blind, infirm or
disabled people, consideration should be given to the installation of an electronically operated device
to warn when discharge takes place. Note: The discharge will consist of scalding water and steam.
Asphalt, roofing felt and non-metallic rainwater goods may be damaged by such discharges.
WARNINGS
The outlet from the Temperature & Pressure Relief Valve must not be used for any other purpose. This also applies to the
Expansion Relief Valve. No other valve is to be fitted between the Cold Water Combination Valve and the cylinder.
The Temperature & Pressure Relief Valve must not be removed in any circumstances. Any of the above will totally
invalidate the warranty.
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ELECTRICAL
The electrical installation must be in accordance with the current I.E.E. wiring regulations.
FITTING IMMERSION HEATER(S) (CONTRACT RANGE ONLY)
These are supplied but not fitted with the Ariston Contract range. A Sealing Gasket is supplied with each element and must
be used to ensure a correct seal. Care must be taken not to cross thread the Immersion Heater(s) when fitting. Each
Immersion Heater is supplied with a Regulation Thermostat and manual reset Thermal Cut-out. This will activate if the
Regulation Thermostat fails. Under no circumstances should this be bypassed.
Although the Immersion Heaters are a standard 2 1 /4" thread, they must not be substituted with anything but an
original Ariston spare part.
DIRECT SYSTEMS
A mains supply of 240V, 3kW (13 amps) is required. Heat resistant cable, round 3 or 4 core 2.5mm2 (to BS6141 table 8)
must be used to connect the electrical supply through the Economy 7 time control switch using either system 'A' or 'B' as
illustrated in fig. 8.
Should the Economy 7 system not to be used, a separate 13 amp supply to each element will be required. Through a
double pole fused isolating switch having a contact gap of at least 3mm on each pole. Make the connection(s) to the
Immersion Heater(s) as per figs. 9, 10. For 500 litre models consult the wiring diagram on the reverse of the inspection
panel.
The Thermostat(s) on the Immersion Heater(s) should be adjusted to trip at 60°C. This is the ideal temperature to prolong
element life in hard water areas. Scale on the sheath builds up more rapidly at temperatures above this causing the element
to overheat and premature failure can occur. Higher temperatures without additional controls would result in scalding.
In addition to the thermostat the Thermal Cut-out will switch power off to the element should the thermostat malfunction,
causing an excessive rise in water temperature. The Thermal Cut-out can be reset manually after the fault has been
corrected.
INDIRECT SYSTEMS
Again for models up to 300 litres a mains supply of 240v, 3kW (13 amps) will be required for the direct Immersion Heater.
Heat resistant cable, round 3 core 2.5mm² (to BS) must be used. For 500 litre models consult the wiring diagram on the
reverse of the inspection panel.
For indirect controls a 240V, 3amp supply is required.
On Comfort models the Indirect thermostat is factory fitted, for Contract models it is necessary to fit the thermostat using
P.T.F.E Tape (Please consult the label on the face of the unit for the correct location in both cases).
The cables must be clamped in position (as previously stated) and the control thermostat should be set at 60°C for the
reasons above. In addition to the thermostat there is a Thermal High Temperature Cut Out should the thermostat fail. Refer
to figs. 11 & 12 for full wiring instructions.
WARNING : THIS APPLIANCE MUST BE EARTHED.
The earth continuity conductor of the electrical installation must be effectively connected to all exposed parts of other
appliances and services in the room in which the water heater is to be installed, conformity with the I.E.E. wiring regulations.
NOTE : Do not switch on the Immersion Heater or fire the boiler until the water heater is full of water.
COMMISSIONING
Check for obvious signs of damage to the cylinder and controls and also that the controls fitted correspond with the
reference quoted in these instructions.
Ensure that the Drain Cock at the base of the water heater is closed before commencing.
1) Open all outlet taps.
2) Turn on mains water supply and allow the water heater to fill.
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