Honeywell DHC, Service Manual

Page: 227 / 262

SDC / DHC Hydraulic Components
EN2H-0221GE51 R0812 227
7.3.11.2.9 Correction of the heat generator after the total flow
temperature
The sensor connected to variable input 1 (2, 3) measures the total
flow temperature in thermohydraulic distributors or in the common
flow.
Correction of the boiler temperature no longer occurs based on
the measured temperature of the boiler sensor, but rather based
on the total flow sensor. The boiler sensor still checks the boiler
minimum and maximum temperatures of the heat generator.
Using a PI control algorithm, the behaviour of the heat generator
can be influenced by a deviation between the total flow setpoint
temperature and the total flow actual temperature.
The PI controller can be influenced via three setting options:
P-part: Proportional part of the controller
Sample time: The sample time is a controller-internal value
which defines the time interval between two
subsequent actuator pulses in the presence of a
control deviation.
Adjustment
time: The adjustment time determines the dynamic
behaviour of the controller based on the set
sample time.
Important note for parameter setting:
The factor for the I-part within the controller is related to the
parameter setting values as follows:
(Ki = factor for the I-part, Ta = sample time, Tn = adjustment time)
Tn
Ta
Kp Ki
=
Total flow sensor