4.2.4
Control
On/off control
The heat input varies between the minimum and the maximum values
on the basis of the flow temperature set on the boiler. It is possible to
connect a 2-wire on/off thermostat or a power stealing thermostat to the
boiler.
Modulating control
The heat input varies between the minimum and the maximum values
on the basis of the flow temperature determined by the modulating con
troller. The boiler output can be modulated with an appropriate modulat
ing controller.
Analogue control (0 - 10 V)
The heat input varies between the minimum and the maximum values
on the basis of the voltage present at the analogue input.
4.2.5
Regulating the water temperature
The boiler is fitted with an electronic temperature control with a flow and
return temperature sensor. The flow temperature can be adjusted between
20°C and 90°C. The boiler modulates back when the set flow temperature
is reached. The switch-off temperature is the set flow tempe 5°C.
4.2.6
Protection against shortage of water
The boiler is fitted with low water level protection based on temperature
measurements. By modulating back when the water flow threatens to be
come insufficient, the boiler remains operational as long as possible. The
boiler issues a warning in the event of no or too little water. With an insuffi
cient flow ΔT ≥ 25 K or too great an increase in the heat exchanger tem
perature sensor, the boiler goes into blocking mode.
4.2.7
Water flow
The modulating control of the boiler limits the maximum difference be
tween the flow temperature and return temperature. In addition, a heat ex
changer temperature sensor is mounted to monitor the minimum water
flow. This limits the maximum increase in the heat exchanger temperature
and monitors the maximum temperature difference between the flow, re
turn and heat exchanger temperatures. As a result, the boiler is not affec
ted by low water flow.
4.2.8
Hydraulic pressure sensor
The hydraulic pressure sensor records the water pressure in the boiler.
Change the threshold value for the hydraulic pressure sensor using pa
rameter
.
4.2.9
Air pressure differential switch
The air pressure differential switch is a protection against a blocked trap or
blocked air supply/flue gas outlet.
Before start-up and when the boiler is in operation, the air pressure differ
ential switch APS measures the difference in pressure between the meas
uring points on the condensate collector p
+
and the air box p
-
. If the pres
sure difference is greater than 6 mbar, then the boiler will lock out. After
eliminating the cause of the breakdown, the boiler can be unlocked.
4 Description of the product
18
7625116 - v.04 - 17012017
