Dual Boiler Plant Control - Honeywell AUTOMATIC CONTROL SI Edition Engineering Manual

DUAL BOILER PLANT CONTROL

FUNCTIONAL DESCRIPTION-
BOILER
LEAD SELECTOR
4
1
16
BOILER
SYSTEM
ON
OUTSIDE AIR
-1
TEMPERATURE
18
BOILER
SYSTEM
24
CONTROL
57
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.
ENGINEERING MANUAL OF AUTOMATIC CONTROL
CHILLER, BOILER, AND DISTRIBUTION SYSTEM CONTROL APPLICATIONS
HEATING SYSTEM
ON-OFF-AUTO
SELECTOR
2
3
AUTO
9
18
BOILER
SYSTEM
OFF
C
NO
NC
VALVES DISPLAY
% OPEN TO
SECONDARY
RETURN
19
DECOUPLER
CROSSOVER
15
HOT WATER TEMPERATURE
RESET SCHEDULE
OUTSIDE AIR
TEMPERATURE
F
13
-15
Fig. 48. Dual Boiler Plant Control Graphic
10
P1
BOILER
ON
PUMP P1
BOILER -1
ON-OFF-AUTO
OFF-AUTO
SELECTOR
SELECTOR
AUTO
AUTO
12
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 IN
SP
HOT WATER
TEMPERATURE
SET POINT
17
43
68
SETPOINT
82
12-14 Valve modulates to prevent entering water from
dropping below low limit setpoint (63 C).
15-18 Secondary water setpoint reset from OA.
19,20 Valve modulates to prevent entering water from
dropping below low limit setpoint (63 C).
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.
333
LOW LIMIT
SET POINT
13
71 63
14
82
22
1
7
31
23
2
8
68
16
SECONDARY PUMP
SYSTEM
ON-OFF-AUTO
SELECTOR
PS
AUTO
SECONDARY
64
HOT WATER
SUPPLY
% SPEED
M15266
29.5
20
1