
17INSTRUCTION MANUAL AIR HEATER TYPE SUH-DC
6 Operating the air heater
6.1 Burner cycle
The air heater’s display shows the current status of the
burner cycle (figure 20).
Figure 20 - Display of the air heater
Display Status Description
0 Stand-by Waiting for heat demand.
1 Reset Software reset.
3 Pre-check Zero position check pressure switch.
4 Pre-purge 30 seconds of pre ventilation by the combustion
fan. The pressure switch is checked.
5 Pre-ignition Ignition without opening the gas valve.
6 Ignition 5 seconds of ignition. The gas valve opens.
7 Flame check The air heater checks if the flame is present.
8 Burn The heater fires up and starts to modulate.
9 Minimum Before the flame stops, the burner will modulate
to minimum power.
10 Burner o The gas valve closes. The flame stops.
11 Post purge Burner fan purges with fresh air.
System fan cools the heat exchanger.
6.2 Minimum firing time
The heater will always fire for a minimum of 4 minutes,
even if the heat demand stops. This is to avoid a large
amount of start and stops and to prevent condensate from
accumulating in the flue system.
NOTICE The heater will try to ignite 2 times before it stops
and gives an error.
6.3 Delta-T-regulation
The air heater can function as a de-stratification fan. This
is called delta-T regulation and it is done via the room
thermostat, with a temperate measurement sensor that is
located on the air heater.
The system fan is activated when the temperature-
dierence between the sensor on the heater (the delta-T
NTC sensor) and the sensor in the thermostat is bigger than
8oC (standard factory setting). This procedure ensures an
even distribution of temperature throughout the building,
thus acting as a fully automatic de-stratification fan.
6.3.1 Switch o delta-T-regulation
Delta-T regulation can be switched o when it is not
desired (e.g. when it causes discomfort). This can be
done in the Settings menu on the room thermostat. See
the user manual of the special Room thermostat for more
information.
NOTICE Delta-T regulation is automatically switched
o when the delta-T sensor (sensor terminal J6) is
disconnected.
6.4 Summer ventilation
The fan can be set to run in the summer. Follow the
instructions in the user manual of the special Room
thermostat.
6.5 Overheating protection
The air heater's heat exchanger and flue system are both
protected from excessive temperatures.
6.5.1 Heat exchanger
An NTC sensor is located near (or on) the heat exchanger.
This sensor monitors the heat exchanger temperature.
If the heat exchanger becomes too hot, this sensor will
cause the heating process to stop. Depending on the
temperature, the air heater performs the following actions:
• Step 1: Power reduction (when possible).
• Step 2: Burner stop, followed by an automatic
restart when cooled down (display: E05 / E36).
• Step 3: Burner stop, followed by a Lock Out. A
manual reset is required. (display L15).
NOTICE A manual reset can be done on the electronic
circuit board or remotely with the special room thermostat.