Dual Boiler Plant Control - Honeywell AUTOMATIC CONTROL Engineering Manual

DUAL BOILER PLANT CONTROL

FUNCTIONAL DESCRIPTION-
BOILER
LEAD SELECTOR
3
4
1
60
BOILER
SYSTEM
ON
OUTSIDE AIR
30
TEMPERATURE
18
BOILER
SYSTEM
24
CONTROL
135
21
SECONDARY
HOT WATER
RETURN
Item No. Function
1 ON-OFF-AUTO function for secondary
pumping system
2 ON-OFF-AUTO function for heating system
3 Selects lead boiler.
4 Heating system start point (Outside air
temperature).
5,6 ON-OFF-AUTO function for primary pumps.
7,8 OFF-AUTO function for boilers.
9 Heating system stop point (Outside air
temperature).
10,11 Operator information.
CHILLER, BOILER, AND DISTRIBUTION SYSTEM CONTROL APPLICATIONS
HEATING SYSTEM
ON-OFF-AUTO
SELECTOR
2
AUTO
9
65
BOILER
SYSTEM
OFF
12
C
NO
NC
VALVES DISPLAY
% OPEN TO
SECONDARY
RETURN
19
DECOUPLER
CROSSOVER
15
HOT WATER TEMPERATURE
RESET SCHEDULE
OUTSIDE AIR
TEMPERATURE
°F
55
5
Fig. 48. Dual Boiler Plant Control Graphic
10
P1
BOILER
ON
PUMP P1
BOILER -1
ON-OFF-AUTO
OFF-AUTO
SELECTOR
SELECTOR
AUTO
AUTO
5
S
25
11
P2
BOILER
OFF
6
PUMP P2
BOILER -2
ON-OFF-AUTO
OFF-AUTO
SELECTOR
SELECTOR
AUTO
AUTO
S
26
27
OUT
PID
SP
HOT WATER
TEMPERATURE
SET POINT
110
155
SETPOINT
180
12-14 Valve modulates to prevent entering water from
dropping below low limit setpoint (145F).
15-18 Secondary water setpoint reset from OA.
19,20 Valve modulates to prevent entering water from
dropping below low limit setpoint (145F).
21-23 Operator information.
24 Icon, selects the Boiler System Control
dynamic display (Fig. 49).
25,26 Software signal selection functions, allows
valve to control secondary HW temperature,
subject to boiler low limits.
27 OA reset valve control PID.
335 ENGINEERING MANUAL OF AUTOMATIC CONTROL
LOW LIMIT
SET POINT
13
160 145
14
180
22
1
7
88
23
2
8
IN 155
16
SECONDARY PUMP
SYSTEM
ON-OFF-AUTO
SELECTOR
PS
17
AUTO
SECONDARY
64
HOT WATER
SUPPLY
% SPEED
85
20
1
M15051