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CTCU UNIT HEATERS INSTALLATION OPERATION AND SERVICE MANUAL
26 of 42
12.3.2 Limit Thermostat
The limit thermostat is located inside the access
door of the heater. See Page 38, Section 16.3. This
control protects the heat exchanger against
overheating.
12.3.3 Burner Lockout Reset Button
The red warning light at the front of the heater will
illuminate when the control has gone to lockout. This
may be caused by flame failure. Press the reset
button on the back of the heater, (See Page 8,
Section 5.1), or the remote reset if installed on site.
If control locks out, do not make more than three
attempts to restart the heater. Dangerous fuel
mixtures can build up. The fault must be traced and
repaired by a registered installer or service
engineer.
12.4 Lighting Instructions
12.4.1 To Turn On Heater
1. E n s u re that the electrical and gas supplies to
the heater are on. Check that the on site
controls are “ON”.
NOTE: The thermostat setting must be above the
ambient temperature for the heater to operate.
2. The automatic firing sequence will begin as
described on Page 22, Figure 11. The heater
will now operate automatically under the control
of the on site controls. Following long shu
t
down periods, the control may go to lockout.
See Page 26, Section 12.3.3.
12.4.2 To Turn the Heater Off
Set the installed remote controls to the “OFF”
position.
The burner will turn off immediately.
The fan will continue to run for a few minutes.
To restart, turn the control used above to “ON”.
12.5 Simple Fault Finding
Some possible reasons for the heater not operating
are:
1. Ga s s upply not turned “ON”.
2. Electricity supply not turned “ON”.
3. The time and/or temperature controls are not
“ON”.
4. The thermostat limit thermodisc may have
operated. This may be caused by an interrup-
tion of the electrical supply or failure of the
distribution fan.
If the thermostat limit thermodisc persistently
operates, there is a fault which must be investigated
by a contractor qualified in the installation and
service of gas-fired heating equipment.
12.5.1 Simple Fault Finding (Burner Faults)
If the burner fails to ignite for any reason, it will go to
locko
ut. This will be indicated by the red light on the
heater or at the remote indicator (if fitted).
1. Press in and release the lockout reset button. If
a remote reset is not fitted, a reset button is on
the rear panel of the heater.
See Page 8, Section 5.1.
Lockout should not occur during normal operation of
the heater and indicates there is a fault condition
which must be corrected.
Press to reset
These are hand reset devices to give further
protection against fan failure.
NOTE: To reset, the heat exchanger must be cool.
Description Part Number
Limit Thermostat 90412100