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© Baxi Heating UK Ltd 2016
18.0 External Low Voltage Controls
18.1
Positioning the Optional Outdoor Sensor
1. The Sensor must be fixed to an external wall surface of the
property it is serving. The wall must face a north or west.
NOTE:
DO NOT position it on a south facing wall in direct
sunlight !
2. The Sensor should be approximately half the height of the
living space of the property, and a minimum of 2.5m above
ground level.
3. It must be positioned away from any sources of heat or
cooling (e.g. flue terminal) to ensure accurate operation. Siting
the Sensor above doors and windows, adjacent to vents and
close to eaves should be avoided.
18.2
Connecting the Optional Outdoor Sensor
1. Ensure the electrical supply to the boiler is isolated. Undo the
securing screws and lift the case front panel off.
2. Disengage the securing tab and hinge the control box
downwards. Undo the terminal block cover securing screw and
remove the cover.
3. Remove one of the grommets, pierce the diaphragm and
insert the wires from the Outdoor Sensor.
4. Leave sufficient slack in the wires to allow the Control Box
to be hinged fully open. Refit the grommet.
5. Connect the wires from the Outdoor Sensor to positions 4
& 5 on M2 as shown. Refit the cover.
18.3
Setting the Sensor Curve
1. Ensure that there is power to the boiler.
2. The Central Heating temperature buttons &
are used to select the desired curve as shown on the graph.
3. Normally the display will show the current temperature of
the water in the boiler (e.g. 41°C). As the buttons are pressed
the curve identification code the will be shown, from
‘
00
’
to
‘
90
’
.
4. To select the most appropriate curve consideration must be
given to the expected outdoor temperature range. This must
then be compared to a boiler flow temperature that will satisfy
the needs of the user, e.g. If outdoor temperatures in the range
0°C to -5°C are anticipated and a boiler flow of no more than
60°C required, select Curve
‘
20
’
.
5. As a further example, if Curve
‘
40
’
is selected, at an outside
temperature of 5°C the boiler flow temperature will be just
below 70°C. In the event of the outside temperature falling to
0°C, the boiler flow will increase to 80°C.
6. Continue with the installation and commissioning of the
boiler as described in the Installation & Servicing Instructions.
7. Explain to the user how to select a different temperature
curve.
N
S
W
E
X
X
Outdoor Temperature
Boiler Flow
Temperature
North
West
1/2 H
2.5m Min
H
Optional Outdoor Sensor