Honeywell AUTOMATIC CONTROL User Manual

ENGINEERING MANUAL OF AUTOMATIC CONTROL
CHILLER, BOILER, AND DISTRIBUTION SYSTEM CONTROL APPLICATIONS
397
Y
33
TI
32
QIR
17
T1
16
TIC
21
TIC
31
TI
18
TI
15
T1
13
TI
19
M
Y
14
M
DDC
TI
01
OUTSIDE AIR
DISTRIBUTION
CENTRAL
SYSTEM
SUBSTATION
CONSUMER
PSF
PRF
M11430
QIR
12
T1
11
HEX1
SSF
SRF
JET
PUMP
DHW
COLD
WATER
Fig. 144. Control of Heat Exchanger for DHW and Jet Pump for SSF.
Control Strategies
1. The SSF temperature depends on the mixing ratio of the
jet pump. Jet pumps do generally not require secondary
circulation pumps. Valve Y 33 on the return pipe provides
a limited amount of flow control. As the valve varies from
full open to 30%, flow through the jet pump varies from
full flow. When the valve is less than 30% open, SSF
flow cannot be guaranteed. TI 32 controls Y33 to maintain
the SRF temperature as reset from outdoor air.
2. Heat exchanger HEX 1 Transfers heat to the isolated
domestic hot water system (DHW). Control valve Y 14
in conjunction with temperature sensor TIC 21 control
the DHW temperature. Because the amount of DHW in
the heat exchanger is small, a fast control system response
time is required. The response times should be:
Controller cycle time < 1 sec.
Actuator on/off time < 1 sec.
Sensor rise time < 2 sec.

Honeywell AUTOMATIC CONTROL Specifications

General

Brand	Honeywell
Model	AUTOMATIC CONTROL
Category	Controller
Language	English