Instructions premix Air heaters type XR10.. 60
Page 8/15
When the heat demand is satisfied, the burner will switch off and the system fan will continue to
run for ca. 3 minutes in order to cool the unit down.
The unit will try to ignite twice before lockout on flame fault.
In the case of flame failure during operation, the heater will attempt one restart.
6.3 Delta-T-regulation
(temperature controlled destratification fan)
In case there is no heatdemand, the delta-T-regulation will be active. (only in case OpenTherm
thermostat is installed).
When the temperature-difference between the sensor on the unit (the NTC) and the sensor in
the OpenTherm thermostat is bigger than the set value (factory setting standard 10°C), the
systemfan will start ,at a regulated speed, depending on the differential temperature difference.
This operation ensures an even temperature distribution throughout the building, thus acting as
a fully automatic variable destratification fan.
Should this delta-T-regulation not be required , the connection between the OpenTherm
thermostat and the unit must be interrupted electrically(by means of a so-called Out-of-service
switch). Alternatively the set point for the delta T regulation to become active, can be set to
15°C (maximum)by turning Potentiometer 2 (P2) fully clockwise. See below.
6.4 High limit protection
The unit contains 2 temperature protections. The NTC thermostat monitors the air temperature
electronically. Should the temperature become too high, the burner will switch off. When the
unit has cooled down , it will automatically restart.
Should the temperature increase to an unacceptable level, , the STB (capillary thermostat) will
interrupt the electric power to the DBC. This thermostat can only be reset manually.
If during operation the power line is disconnected, the STB can switch because of the internal
heat in the appliance. It has to be reset before the heater functions again.
6.5 Description spare parts
List of abbreviations:
DFC:
Digital Fan Control. This is the central regulation printed circuit board
that communicates with the room thermostat and modulates the premix
fan, it also determines the system fan speed.
DBC
Digital Burner Control, situated on the gascontrol. This monitors the
ignition and burner sequence, whilst supplying power to the premix-fan.
NTC
Negative Temperature Sensor. This sensor measures the temperature of
the blown out air.
STB
This mechanical maximum thermostat that measures the temperature of
the blown out air by means of a capillary sensor. The set value cannot
be changed.
PWM
This is the pulsating 24 Volts signal of the DFC to the pre-mix fan. The
PWM regulates the modulation and the start-up speed.
