Maintenance FN
96
Maintenance FN
This function is intended as a service function for the chimney sweeper and/or as a simple burner
switch for the exhaust measurement. The preset output (generally 100%) is switched on for the set
time after the burner has been started. In addition, the heating circuits set in the input variables are
activated
with the maximum admissible flow temperature T.flow MAX
. The value of the output
variable T.flow SET of this heating circuit is displayed as 5°C during the active maintenance function.
These targets could also be reached via the manual mode (switch corresponding outputs to
MANUAL/ON). Assuming that the user does not have a manual for the controller or that the person
does not have enough time to read the entire manual, this function should make things easier.
Use the input variable "
EXTERNAL SWITCH
" to activate the maintenance function via a specially
installed switch or via a switch output of another function without any inputs at the controller being
activated. An "External switch" must be set to "ON" for the duration of the maintenance function (
no
runtime limit
). The function must be deactivated again via this switch.
Input
variables:
Output
variables:
External switch
Status burner demand, indication of the output
involved functions
= Indication of the heat-
ing circuits
Burner output, indication of the speed control
output
Entire menu view:
FUNCTION START
---------------------
Press the scroll wheel to activate the burner and the heating
circuits => number
FUNCTION STOP
DES: FL G INSP
Status: OFF
The function is deactivated (stopped)
Runtime: 0 Min
Remaining burner runtime
INPUT VARIABLE:
OUTPUT VARIABLE:
Ttl runtime: 20 Min
Total burner runtime after function start
Burner outp.:
100%
Desired burner output during service time
The function block provides the burner output as an output variable. It can be assigned to a speed
output or an analogue output. For instance, the burner performance can be controlled (assuming you
have the appropriate burner technology) via analogue output 15 or 16 (analogue output 0 - 10V).
The output of the burner performance is dominant in the maintenance function. In other words, no
other analogue signal is allowed during maintenance (such as from DHW demand). However, digital
signals can overwrite the analogue value at any time.
Once the burner demand has been switched off (function stopped), the heating circuits involved still
remain active for three minutes to take the residual heat from the boiler. If the mixer behaviour is
detected as "close" in the heating circuit, then the mixer is set to "closed" for 20 minutes (= maximum
remaining runtime) and the heating circuit pump is switched off. Only then does the heating circuit
return to the set operating mode.
