Honeywell DHC, Service Manual

Page: 193 / 262

SDC / DHC Hydraulic Components
EN2H-0221GE51 R0812 193
The current hot-water temperature overshoots the hot-water
circuit setpoint by half the amount of the hot-water switching
differential. After switching-off the heat generator, the tank loading
pump is stopped only after a time delay to prevent a safety
switch-off in case of high temperatures. The set value can be
adjusted to the holding capacity of the hot-water tank used.
Excessively long extended running times unnecessarily interrupt
heating and increase the temperature in the hot-water tank.
Depending on the parameter setting, a setpoint present in the
system may or may not be forwarded to the heat generator during
the extended running time
The boiler is operated according to the following rules during a
tank pump extended running time:
– Parallel hot-
water peration Hot-water
priority mode Conditional hot-
water priority mode
–
HC setpoint HC setpoint
DC
setpoint MC
setpoint
AUTO Active OFF OFF Active
OFF OFF OFF OFF OFF
For complete loading of a hot-water tank by means of automatic
measuring point switch-over between tank sensors 1 and 2 (layer
loading). The measured value of the hotter sensor (SF1 or SF2) is
evaluated for the activation of the loading pump. Termination of
loading is carried out on the basis of the measured value of the
colder sensor. The set values for the hot-water setpoint
temperature and the specified hot-water switching differential
continue to apply.
5.2.4 "DHW" menu, pg. 77
Quick hot-water connection in cascaded systems
With cascaded systems, it is often the case that all heat
generators are often not needed for hot-water production. In
addition, the required heat generators must be connected faster
than when heating.
If there is a demand for hot water, a fixed value of 10 seconds is
used for connection of the subsequent stages up to the set
Pump extended running
loading cancellation
NOTE
Tank sensor 2
See also
Function