42007492-001 R6
Caution:
Isolate
power supply and
make safe before
wiring the unit to
prevent electric
shock and equipment
damage. Installation
should be carried
out by a competent
person.
L641A - Cylinder Thermostat
Installation Instructions
1
3
5
Mounting Position
Cover Removal
Wiring Diagram
2
Pre-insulated cylinder
preparation
4
Wiring to terminals
80°C
min
70
60
50
40
L641A1039
80°C
min
70
60
50
40
L641A1039
to
Height
The cylinder thermostat
should be mounted to
of the way from the bottom
of the cylinder.
Cover installation is the reverse of above
80mm
45mm
Remove a section of
insulation as specified.
Clean cylinder surface
to ensure good surface
contact.
All wiring must be in accordance with I.E.E. regulations.
Use heat resisting flexible cable rated at 85°C.
A switch, having contact separation of at least 3mm in all
poles, must be incorporated in the fixed wiring as a means of
disconnecting the supply.
The thermostat is a class II (double insulated device) requiring no
earth connection.
The heating system must be appropriately fused with a fuse rating
of no higher than 3 amps.
For use in normal domestic environments.
EMC compliance considerations
Keep AC mains supply/load cables separate from signal wiring.
Refer to Code of Practice EN61000-5-1 and -2 for guidance.
Use connections C and 1 when
system operation is required on
temperature fall
*
Terminal 2 used on
Y-Plan systems
L641
230V
~
50..60Hz
1 2
Heating Load
Timer/Programmer
3 AMPS
C
*
Specification
Switch Action: SPDT, Type 1 CL.
Switch Rating: 230V~ 4(2)A 50...60Hz
Temperature Setting Range: 40...80°C
Differential: Approximately 10°C non-adjustable
Ambient Temperature Range: 0...55°C
Cylinder Surface Temperature Range: 0...95°C
The L641 is a water temperature thermostat designed for surface mounting on domestic hot
water cylinders. It is supplied complete with mounting strap for rapid and easy installation,
so draining of the system or tapping the cylinder is not necessary. The desired temperature
control point is set by the clearly scaled temperature selector on the front cover.
Features
• Snap action SPDT Micro
Switch™.
• Wiring terminals are easily
accessible.
• Tamperproof temperature
setting.
• Optional manual setting
knob supplied
8mm
max