DORCHESTER DR-RS 105, Инструкция по установке, наладке и обслуживанию

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Functioning of the water heater
14 Instruction manual DR-RS
2
gis
2.4.1 Water temperature protection
By means of the frost, high-limit and safety thermostats, the burner control
monitors three temperatures related to safety.
Table 2.1 explains the operation
of the thermostats with sensors.
2.4.2 flame probe
To ensure that no gas can flow when there is no combustion, an flame
probe
(27) has been fitted. The burner control uses this rod for flame detection,
by means of ionisation detection. The burner control cuts in immediately, as
soon as it detects that gas is flowing, but there is no flame.
2.4.3 Pressure switch
The pressure switch guarantees the discharge of the flue gases and the supply
of air. The default position of the pressure switch is open. If there is sufficient
pressure difference across the air restrictor
(10) , the air pressure switch (18) will
close. However, in the event of a fault, the pressure switch will be tripped open
and the heating cycle will be interrupted.
Table 2.2 shows the trip point per water heater.
Table 2.1 Temperature protection
Protection Description
Frost thermostat If the frost thermostat sensor (25) detects a temperature of 20°C or lower, the
water heater’s heating cycle will start. See paragraph 2.3 The water heater’s
heating cycle .
High-limit thermostat If the high-limit thermostat sensor (20) detects a temperature greater than
84°C, the high-limit thermostat will open. The heat demand will cease and the
burner control will stop the heating cycle until the high-limit thermostat closes
again. At that moment, the burner control resets the water heater and the
heating cycle resumes. The high-limit safeguard serves to prevent
overheating and/or excessive formation of scale in the water heater.
Safety thermostat If the safety thermostat sensor (22) detects a temperature greater than 93°C,
the safety thermostat will open. The heat demand will cease and the burner
control will immediately stop the heating cycle. A lockout error of the burner
control takes place. This must be manually reset, before the water heater can
be put back into operation.
Table 2.2 Pressure switch trip points
Appliance Pressure differential [Pa]
Closing Opening
DR-RS 25 > 2
00 < 170
DR-RS 40 > 2
7
0
< 240
DR-RS 65 >
255
< 2
2
5
DR-RS 85 > 610 < 580
DR-RS 105 > 220 < 190