Honeywell SDC Service Manual page 237

SDC / DHC
7.3.12.3.3
7.3.12.3.4
EN2H-0221GE51 R0812
Control characteristics
• The heat generator that was switched on last adjusts the
system to the set nominal temperature.
• All other heat generators operate at the set maximum
temperature (base load).
• The boiler stage number can be reduced as soon as the
adjusting stage has withdrawn its demand to the heat
generator and the boiler temperature has risen above the
setpoint temperature plus the set switching differential.
• For each heat generator the displayed setpoint temperature
always is the currently demanded temperature to be adjusted
to.
• A heat generator that is not available in the system
(malfunction, external disable or outside temperature disable)
is ignored within the stage sequence. The next available heat
generator will be switched on instead.
Delay, enabling, full load in cascade operation
The switch-over power set within the cascade selection level is
only intended for the operation of automatic stokers. As long as
the last burner stage is not started, all burner stages up to that
point which are currently operating are reduced to the specified
switch-over power (power limit). When switching on the last
burner stage, all other automatic stokers are enabled to 100%
power (full load) after another progression of the dynamically
determined switch-on delay (at least 5 min.).
If the system is operating with all available stages, no power limit
is active for the automatic stokers. If a level is reduced, the set
switch-over power for the automatic stokers is once again in
effect.
Hydraulic Components
237