Safety Systems; Dimensions - Daikin D2C20ND028A5AA Manuel D'installation

3.1

Safety systems

The unit is equipped with several safety systems, to protect it against
dangerous conditions:
Flue safety system: This is controlled by the flue gas temperature
sensor located on the flue outlet part of the boiler. It is activated
when the flue gas temperature exceeds safety limits.
Overheating safety system: This is controlled by the safety limiting
thermostat. It is located on the main heat exchanger and stops the
unit when the flow temperature reaches 100°C, to avoid boiling of
the water, which may damage the unit.
Pump anti-blockage system: The pump operates for 30 seconds
every 24 hours during long periods of inactivity to ensure it does not
get stuck. To enable this function, the unit must be connected to the
power supply.
Three-way valve anti-blockage system: In cases where the unit is
non-operational for prolonged periods of time, the three-way valve
switches its position every 24 hours to prevent it from getting stuck.
To enable this function, the unit must be connected to the power
supply.
Safety against dry operation: This is controlled by the pressure
sensor. It turns off the unit and ensures system safety when the
water pressure of the heating installation falls below 0.6 bar for any
reason.
Flame ionisation control: This is controlled by the ionisation
electrode. It checks whether a flame forms on the burner surface or
not. If there is no flame, it turns the unit off to stop gas flow and
warns the user.
High pressure protection:
▪ Pressure sensor: When heating system pressure reaches
2.8 bar, control unit stops heating operation thus preventing the
pressure from rising.
▪ Safety valve: When the water pressure of the heating circuit
exceeds 3 bar, some water is automatically drained from the
safety valve to keep the pressure below 3 bar thus protecting the
boiler and heating installation.
Automatic air vents: There are two air vents; one on the pump,
other on the heat exchanger. They help discharging the air inside the
installation and heating circuit to avoid air traps and consequent
operational problems.
Frost protection safety system: This function protects the unit and
heating installation from frost damages. It is controlled by the flow
temperature sensor, which is located at the outlet of the main heat
exchanger. This protection activates the boiler pump when the water
temperature drops below 13°C and it activates the burner when the
water temperature drops below 8°C. The unit keeps running until the
temperature reaches 20°C. To enable this function, the unit must be
connected to the power supply and its main gas valve must be open.
Any damage caused by frost is not covered by the warranty.
Low voltage safety system: This is controlled by the control unit.
When the supply voltage drops below 170 Volt, the boiler goes to
error mode. It is a blocking error and the boiler will operate without
reset after supply voltage is above 180 Volt. It is recommended to
use a voltage regulator of suitable power and type in locations with
voltage fluctuations below this limit for faultless operation.
High electric supply current protection system: A fuse on the
control unit protects equipment and wiring against the damaging
effects of electrical faults which is caused by excess currents, and
disables equipment which is faulty. The fuse "blows" (opens) when
the current carried exceeds the rated value for an excessive time.
Automatic by-pass system: This ensures that the flow is at all
times continued, to avoid overheating of the heat exchanger. This
system is also supported with a special by-pass function in the
control unit software.
D2C20ND028A5AA + D2C24ND035A5AA
Wall-mounted condensing boiler
3P469346-10J – 2018.05
Combustion control safety system: Boiler control unit monitors the
flame to avoid bad combustion and risky conditions. It also makes
self-inspection against its own malfunctioning and to keep emissions
always at a low level.
3.2

Dimensions

Top view
Front view and right side view
Bottom view of model D2C20ND028A5AA and
D2C24ND035A5AA
37.5
90 65 65 68
3 About the unit
294.4
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Installation manual
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