AERCO Combination Control Panel (CCP) - Manual (Page 4)

Sequence of Operation
The four KC Boiler Combination plant shown in Figures 1
and 2 is typical of plant piping and wiring arrangements.
The KC boilers dedicated for heating-only must be
ordered for Control Mode -5 for BMS mode operation.
The boilers for combination duty must be ordered for
Combination Mode -6. The Combination mode boilers
internal setpoint should be adjusted to the design water
temperature used to size the coil in the storage/generator.
The tank aquastat should be set at the desired domestic
water tank temperature.
As the tank aquastat closes sensing a demand for domes-
tic water recovery, the CCP will activate the coil pump and
Combination Boilers #1 & #2. The boilers will modulate
their own input as needed to maintain their setpoint. The
boilers will automatically reduce their input as the coil
water temperature approaches setpoint. Under heavy
load, the boilers will increase their input for maximum
recovery. The boilers and coil circulating pump will con-
tinue to operate until the tank aquastat is satisfied.
The system start within the Model 168 Boiler Management
System(BMS) activates the heating system circulating
pump and the heating-only modules. Heating Boilers #I &
#2 will fire normally as controlled by the BMS and modu-
late input up as the heating load increases. When both
dedicated heating modules reach 100% input, the BMS
Auxiliary contacts will close, activating the CCP panel.
The CCP will then open the motorized valve in the supply
piping. When the valve reaches 100% open, the end
switch will allow the CCP to transfer the control of both
combination boilers to the BMS. The BMS will modulate
the input of all four boilers to meet the needs of the heat-
ing system.
As the heating system temperature increases to the
required system setpoint, the auxiliary contacts of the
BMS will open. The opening of the Auxiliary contacts can
be adjusted from the keyboard of the BMS. As the auxil-
iary contacts open, the CCP closes the motorized valve to
isolate the domestic loop from the heating loop. The
control of the combination boilers is also returned to their
internal setpoint controls, and will only fire upon a signal
for domestic water production. If the domestic tank aquas-
tat closes while the motorized valve is open for heating,
the CCP will automatically close the valve and return
Combination Boilers #I & #2 back to domestic recovery
service. This internal feature provides priority to domestic
water heating.
Represented by:
HEAT EXCHANGERS • WATER HEATERS • BOILERS
CONTROL VALVES • STEAM GENERATORS
HOT WATER SYSTEMS
AERCO INTERNATIONAL, INC. • 159 PARIS AVE., P.O. BOX 128 • NORTHVALE, N.J. 07647-0128
(201)768-2400. FAX 201-768-7789
CCP-1 12/95 5M
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