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HEATING BOILERS: Astra H-25 E, Astra H-32 E, Astra H-45 E
of the front panel buttons, see “Electronic boiler regulator KR-4.3D” and “Boiler kindling procedure”.
• ReaR conTRol Panel
The following safety devices are installed in the rear control panel: thermal fuse 1 and electric fuse 2 (Fig. 10). The purpose
of the thermal fuse, otherwise called the maximum boiler temperature emergency thermostat, is to switch off the boiler
ventilator if water temperature in the boiler exceeds the maximum permissible
95°C due to unforeseen reasons. The temperature sensor of the thermostat is
installed in a dedicated sleeve 19 (Fig. 1). The burning intensity decreases when
the ventilator is switched off and the water temperature decreases. When the
emergency thermostat trips, the lamp of the ventilator switch 3 on the front
panel switches off (Fig. 9) and the lighting indicator bulb 4 “Firing off” on the
electronic regulator lights up (Fig. 11). In this case, it is necessary to find out
the causes of tripping and to remove them. After the boiler cools down, the
emergency thermostat can be returned to its normal operating mode. For this
purpose, unscrew its cover and depress the red button.
The cause of overheating of the boiler and tripping of the emergency thermostat must be found and
removed. If this is not done, the risk of serious damage to boiler equipment as well as hazard to human health
and life remains. If the user cannot locate and remove the cause of tripping of the emergency thermostat, a
professional servicing company must be consulted!
The electric fuse is designated to protect the elements of the electric circuit in case the current in the mains exceeds 2 A. If the
fuse is damaged, the boiler will not switch on and its indicator lamps will not light. In this case, remove and replace the fuse.
The rear control panel of the boiler is grounded.
• elecTRonIc boIleR ReGUlaToR KR-4.3D
The electronic boiler regulator KR-4.3D is designed for controlling a solid fuel boiler. It controls the ventilator in accordance
with the PID regulation law and the circulation pump of the system, by position “on-off”. The regulator adjusts the rotation
speed of the ventilator using the impulse method, thus intensifying or slowing down the burning process. The speed of
the ventilator is defined in proportion to the actual temperature deviation from the set temperature, the duration of the
deviation and the speed of temperature change of the boiler. The regulator reacts to the water temperature in the boiler and
fig. 11 front panel of regulator KR-4.3D
1 – digital temperature indicator; 2 – temperature setting buttons; 3 - lamp
“Firing on”, 4 - lamp “Firing off”, 5 - lamp “Pump on”, 6 - lamp “Ventilator on”,
7 – control button for the programmable channel, 8 – lamp “Programmable
channel on”
1
2
7
3
4
5
6
8
1
2
fig. 10 Rear control panel
1. Thermal fuse ; 2. Electric fuse.
smoke temperature in the flue. A NTC-type sensor for
measuring water temperature is installed in a special
sleeve 19 (Fig. 1), the outer side of which is submerged
in water inside the boiler. A PT-type sensor for
measuring smoke temperature is installed in a special
sleeve 10 (Fig. 1), which is located in the flue gases
duct of the boiler.
The digital temperature indicator 1 (Fig. 11) indicates
both the measured and the set temperature of water
in the boiler. The setpoint temperature is adjusted
using the buttons 2. After a short press of “+” or “-”
the digital indicator 1 starts showing the setpoint
temperature of the boiler water. In order to change it,
