38
16. Sequence of operation
Activation of the time clock and/or room thermostat starts the boiler. The display panel indicates the flow temperature in the
Central Heating system as illustrated below:
The PCB checks the pressure of the primary circuit, if the pressure measured is 0.8 bar or lower, the boiler will lockout after 40
seconds. The error code
E02
will appear on the LCD and the pump will stop.
If the pressure measured is above 0.8 bar, the boiler ignition sequence will begin.
At first, the fan starts and the speed increases to the required ignition speed (3460 rpm), once this speed has been achieved, the
safety coil of the gas valve is supplied with 230V DC, after 8 seconds the boiler checks that the burner has lit, if the boiler does
not sense that the burner has lit, the error code
E04
will appear on the display, should this error occur, the boiler will attempt to
relight two more times (20 seconds between each attempt). After this, should the boiler still not sense a flame, error code
A03
will
appear on the LCD. Should the boiler detect that the burner has lit, the boiler continues to regulate as follows.
The NTC fitted on the outlet of the primary circuit exchanger is the only NTC to adjust the heat output of the boiler according to
the adjustable setting point. This point is adjustable from 25°C to 85°C by the user. This NTC relays information to the PCB,
which in turn modulates the burner by adjusting the speed of the fan.
When the NTC senses that the set temperature has been achieved (+ 4°C to the temperature set by the user), the burner will go
out. To avoid excessive burner lighting, an anti-cycle timer can be set between 0 to 7 minutes in menu
4
line
48
(see Section 17
Adjustments and Settings).
The speed of the pump can be set at two levels. The PCB controls the speed of the circulation pump depending on the speed set
in menu
4
line
41
. Setting
410
will cause the pump to operate continually at high speed, and setting
411
will cause the pump to
modulate between high and low speed depending on the
∆
T between the inlet and the outlet. If the
∆
T is greater than 20°C the
pump will run on high speed and if the
∆
T is less than 20°C the pump will run on low speed.
N
OTE
: T
HE DEFAULT SETTING FOR THE PUMP IS HIGH SPEED
.
Central Heating Mode
Central heating
mode
ON
Room thermostat
contact
ON
Summary of Contents for Minima HE System 24 Nat
Page 19: ...19 1 2 A A Fig 14 Fig 16 Fig 13 11 Installing the Boiler continued Fig 15 P P ...
Page 22: ...22 Fig 21 Fig 22 Fig 23 ...
Page 31: ...31 WIRING DIAGRAM FOR CONNECTION TO AN OPEN VENTED CYLINDER DIAGRAM B ...
Page 32: ...32 WIRING DIAGRAM FOR CONNECTION TO AN MTS UNVENTED CYLINDER DIAGRAM A ...
Page 61: ...61 24 Benchmark Commissioning Checklist ...
Page 62: ...62 25 Service Interval Record ...
Page 63: ...63 ...
