DOMINATOR INSTALLATION AND OPERATION INSTRUCTIONS
Page 32
High Limit (Aquastat)
The high limit is located in the left side area of the boiler/
water heater. A remote capillary bulb is run to a well on
the outlet side of the supply header. The high limit can
be reset by depressing the black rubber plug in the front
top jacket panel.
The water heater high limit should be set a minimum of
20°F
,
11°C
higher than the operating control. Refer to
the HOT WATER SUPPLY section for the proper supply
water temperature.
Flow Switch
A fl ow switch is provided in the water outlet piping to
prevent the boiler/water heater from firing without
adequate water fl ow through the heat exchanger.
Low Water Cutoff
If the boiler is to be installed above radiation or if
required by other codes or regulations, install a low
water cutoff in appropriate piping. Wire the switch and
any external controls in series to the "Interlock" contacts
in the junction box (see the attached Connection
Diagrams for details). Ensure that the low water cutoff
device(s) will function properly.
Flame Sense Module
The fl ame sense module is located on the control tray.
It is an intermittent pilot control device that controls the
pilot gas fl ow, spark energy to ignite the pilot gas and
the main valve(s) once pilot ignition has been proven.
Two fl ame failure alarm terminals are provided on the
fl ame sense module. For CSD-1, these terminals will be
utilized to shut the unit down in case of fl ame failure.
The two terminals will be connected to a lockout control
module located on the control tray under the fl ame
sense module. This lockout control module contains a
magnetic latch relay that requires manual reset when
de-energized. To reset after fl ame failure, push and
release the momentary contact switch located within the
front control panel.
Relay Board
The relay board is located in the control tray. It provides
sequencing of the gas valves and blower(s) based on
the staging controller's input. It also provides the
following time delays for proper unit operation:
• A 40 second prepurge when stage 1 is energized.
• A 10 second pressure switch sequencing delay
when the blowers switch from low fi re to high fi re.
The delay enables the blower to come up to speed
before the high pressure side of the pressure switch
confi rms proper air fl ow.
These time delays are set within the separate time delay
board connected to the relay board.
Gas Pressure Switch
An optional low and/or high gas pressure switch will shut
down the 24V circuit if excessively high or low gas
pressure exists in the gas train or supply piping.
BTC Staging Control
The staging control is located at the front of the control
tray. It utilizes various temperature sensors to calculate
boiler/water heater demand and adjust the stages as
required. Various features of the control can be adjusted
from the 3-button panel on the controller. To change
settings of the staging controller, press and hold all three
buttons approximately 2 seconds until the “adjust”
screen appears, then release them. The staging
controller provides 6 modes of operation based on the
requirements of the system. The desired mode can be
set manually from the controller. Each mode is defi ned
b e l o w. R e fe r t o t h e c o n t r o l m a n u fa c t u r e r ’s
documentation for more information on the controller
and its adjustment features.
At the rear of the controller, two DIP switches are
provided to allow an installer to modify staging control
operation. These switches are factory set to provide a
"lockout" with minimum adjustment capabilities in the
fi eld. However, for experienced installers and operators,
changing these switch settings can offer many fi ne-
tuning features. Consult the control manufacturer's
documentation for more information on the controller
and its adjustment features.
CAUTION: DO NOT change DIP switch or controller
settings unless you have completely read and
understood this document and the control
manufacturer's instructions. Doing otherwise will
lead to improper stage control operation.
Mode 1: Setpoint control.
Dominator piped in parallel
with the system. The firing stages are operated to
provide a setpoint temperature at the boiler/water heater
outlet.
SETPOINT OPERATION - The control operates the
boiler stages to maintain the programmed temperature
at the boiler/water heater outlet sensor whenever a heat
demand is present.
Mode 2: Setpoint control.
Dominator piped in primary/
secondary confi guration. An additional system sensor
is required to properly control the system supply
(primary loop) temperature. The firing stages are
operated to provide a setpoint temperature in the
primary loop.
SETPOINT OPERATION - The control operates the
boiler/water heater stages to maintain the programmed
temperature at the supply sensor (primary loop sensor)
whenever a heat demand is present.
