5.3
IMMERSION HEATER SAFETY CUT-OUT
The immersion heater incorporates an in independent non self-
resetting over temperature cut-out device to prevent excessive
water temperatures.
In normal operation the reset pin positioned to the side of the
control knob and indicated by a triangle (with the word ‘safety’
below) will be approximately 2-3mm below the upper surface of
the thermostat cap.
Should the over temperature cut-out operate, the reset pin will be
pushed upwards to become level with or slightly above the cover.
Wait until the temperature has fallen sufficiently. Then Investigate
and identify the cause of the cut-out operation and rectify the fault.
Then manually reset the cut-out by pressing in the reset pin to its
normal operating position using hand pressure only with a suitably
sized implement.
! WARNING !
Before removing the immersion heater covers to either
reset the safety cut-out or check/alter the thermostat
setting, ensure that the electrical supply is isolated.
Ensure the cover to the immersion heater cover is replaced
correctly and the retaining nut is fitted. Finally switch the mains
electricity supply back on.
5.4
DUAL THERMOSTAT
A Dual Thermostat (a combined control and high limit thermostat)
is supplied separately with the unvented hot water safety kit. This
is fitted into the sensor pocket in the cylinder (refer to Figures 2-6
to 2-10, as appropriate, for position) to control the operation of the
boiler or heat pump primary coil.
The cylinder control thermostat has an adjustment range between
25°C and 65°C. It is recommended that it is set to 60°C.
The high limit (overheat) thermostat will automatically operate at
90°C.
For details on the correct wiring connections, refer to either Figure
5-3 or 5-4 (as appropriate).
5.5
2-PORT VALVES
To comply with the regulations governing the installation of indirect
unvented hot water cylinders, a 2-port motorised valve must be
fitted in the primary flow to prevent gravity circulation when the
boiler switches off.
Your Grant MonoWave indirect HP unit has been supplied with a
2-port motorised valve, which will act as a positive energy cut-out
should the high limit (overheat) thermostat (in the dual thermostat)
operate. If this happens, the 2-port zone valve will operate and
shut off the primary flow to the cylinder.
When installed as part of an “S-plan” type of heating control
system, this motorised valve will also control the temperature of
the domestic stored water via the cylinder control thermostat,
(located in the dual thermostat). Refer to Figure 5-2 for a
representation of an “S-plan” system using a Grant MonoWave
indirect HP cylinder and a Grant Aerona³ heat pump.
This valve should be wired in accordance with either Figure 5-3
or 5-4 (as appropriate) for a Grant Aerona³ heat pump, to comply
with current legislation.
For other makes of air source heat pump, other than the Grant
Aerona³, consult the heat pump manufacturer for electrical
connection details.
5.6
HEAT PUMP INTERFACE BOX
The Grant EP002 heat pump interface box (supplied with all Grant
Aerona³ air source heat pumps) is designed to provide the voltage
free switching for the Aerona³ air source heat pump, using the
space heating and hot water switched live outputs from the control
system wiring centre.
This box can be installed next to the heating system wiring centre.
Alternatively, it can be located nearer to the Aerona³ heat pump,
but NOT be installed externally.
Refer to the Aerona³ installation instructions for further details.
This interface box is NOT required when the cylinder is used with
a Grant oil boiler.
Page 23
Section 5: Electrical
Summary of Contents for HPMONO/IND125
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