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Third Part
(edition-0106)
Safety Thermostat
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1
Function
The safety thermostat A in Figure 1 is a device
that senses the temperature of the primary circuit
water which flows in the outlet pipe of the primary
heat exchanger.
If the temperature control system of the boiler
fails and the temperature of the primary circuit
reaches a dangerous temperature, the safety
thermostat opens the electric circuit that supplies
the on-off operators of the gas valve.
Consequently, the full sequence ignition device
attempts to light the burner and, at the end, locks
the boiler and lights the lock-out signal lamp.
A
Figure 1
2
Checks
A
Overheat temperature value
1) Set the temp. control knob to its maximum
position and run the boiler.
2) Allow the boiler to reach its maximum
operating temperature (monitor the
temperature gauge on the instrument panel).
The boiler should maintain a temperature
below that of the safety thermostat and no
overheat intervention should occur.
Warning: Isolate the boiler from the mains
electricity supply before removing
any covering or component.
B
Electrical function
1) Remove all the case panels and the lid of the
sealed chamber.
2) Disconnect the safety thermostat and check
its electrical function. Normally (no
intervention) the contact must be closed
(electrical resistance zero
Ω
).
3
Removal
Warning: Isolate the boiler from the mains
electricity supply before removing
any covering or component.
1) Remove all the case panels and the lid of the
sealed chamber.
2) Unscrew the three screws B (Figure 2).
B
Figure 2
3) Disconnect the three connectors of the safety
thermostat.
4) Remove the probe holder spring C freeing the
safety probe D (Figure 3).
Safety Thermostat
1) Function
2) Checks
3) Removal
RIVA FP SERVICE MANUAL - REV A
15-1
