Technical information

at both speeds: high speed with the aid of a
pressure difference, low speed by means of
a temperature increase.
If, when the burner is ignited, the pressure
rises or falls by more than 0.1 bar within 4
seconds, then the burner will be switched
off. The control system then switches to the
pump test phase until sufficient pressure
difference has been created.
For central heating and hot water operation
the appliance modulates back when
∆
T >
32 °C. The
∆
T regulation in the programme
functions as follows:
∆
T
< 32 complete capacity
utilization
32 <
∆
T < 40
capacity is reduced linearly
to low load at 40 °C
40 <
∆
T < 45
low load
> 45 off
If the appliance is in central heating use and
T
return
> T
supply
+ 5 °C, the burner will be
switched off. For hot water operation, this
check will only be carried out 20 seconds
after ignition in connection with the heat in
the tap boiler.
26.3 Max. temperature protection
The maximum temperature protection is
obtained with the aid of the supply and
return sensors. If one of these sensors
registers a temperature in excess of 93 °C,
the burner will always be switched off.
If one of these sensors registers a
temperature in excess of 105 °C, the control
system blocks all further heating demand
and starts pumping through the central
heating circuit in order to remove the
superfluous heat as quickly as possible. ‘H’
appears in the status display and the
temperature display will show the supply
temperature.
If during burning, one of these sensors
registers a temperature in excess of 105 °C,
the appliance will be immediately blocked
with a flashing ‘H’ on the status display and
the supply temperature on the temperature
display. Pressing the reset pushbutton on
the display can only discontinue this
blocking. With a temperature in excess of
118 °C,
will be displayed.
The control system will then perform the
following three measurements.
1. Before the control system ignites the
burner, the difference between supply and
return temperatures must be less than
20°C.
2. The following check measurement
will be carried out each time the burner is
ignited. Both the supply temperature and
the ∆T will be measured just before the
burner is ignited. If the control system does
not detect an increase of three degrees in
the supply temperature or in ∆T after 10
seconds of burning, the burner will be
immediately shut down. The control system
will wait until ∆T is less than 5 °C and (if
there still a demand) will then make another
attempt at ignition. If this test is not
successful after three attempts, the control
system will block further operation with a
flashing ‘2' on the status display and the
supply temperature on the temperature
display.
Once in every two hours the difference
between supply and return temperatures
must have been less than 5 °C. Is this not
the case, than the burner will not be ignited
until this is the case.
While the system is waiting for this condition
to occur, the status display will show a ‘2'
continuously, and the temperature display
will show the supply temperature. A
combustion cycle will not be interrupted by
this protection.
26.4 Static pressure
The static pressure P in the appliance is
monitored. The following situations can
occur:
P <= 0.2 bar
All heating demand will be blocked, the
pump will be switched off and the status
display will show a P continuously.
The static pressure will be shown in the
temperature display. This is a indication that
the user must top up the appliance.
Page 40 ECO HOMETEC
(
UK
)
LTD
.