Burnham Sage Boiler Control Specification Sheet

Consulting Engineer

Suggested Specification

Controls For

Multiple Burnham Commercial Cast Iron

Hot Water Boilers

Revision

January 26, 2010

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Lancaster, Pennsylvania 17605-3939

www.burnhamcommercialcastiron.com

P.O.Box 3939

Phone: [phone]

2.4 Boiler Control System

A Scope of Supply

Supply a Boiler Control System to provide safety interlocks and water temperature control.
The control system shall be fully integrated into the burner control cabinet and incorporate
single and multiple boiler control logic, inputs, outputs and communication interfaces. The
control system shall coordinate the operation of up to eight (8) fully modulating hot water
boilers and boiler pumps. The control system shall simply control boiler modulation and
on/off outputs based on the boiler water supply temperature and an operator-adjusted
setpoint. However, using parameter menu selections, the control system shall allow the
boiler to respond to remote system water temperature and outside air temperatures with
Domestic Hot Water Priority (DHWP) and Warm Weather Shut Down (WWSD) or Building
Automation System (BAS) firing rate demand, remote setpoint or remote start/stop
commands.

B Boiler Control

Using PID (proportional-integral-derivative) based control, the remote system water
temperature shall be compared with a setpoint to establish a target boiler firing rate. If the
secondary loop GPM is greater than the primary loop GPM, firing rate is increased in
response to secondary loop temperature decreases. When the remote system temperature
is near the boiler high limit temperature, the boiler supply sensor shall limit the maximum
boiler supply temperature to prevents boiler High Limit Trips. Alternately, using parameter
menu selections, the control system shall allow the boiler to respond to directly to boiler
supply temperature and setpoint to establish a target boiler firing rate while remote system
water temperature is used for display purposes only. Each boiler’s fuel flow control valve
shall be mechanically linked to the air flow control device to assure an air rich fuel/air ratio.
All the logic required to ensure that pre-p urge, post -purge, light-off, and burner modulate
cycles are automated shall be provided.

C Hot Water Temperature Setpoint

When the controller is in the local control mode, the control system shall establish the
setpoint based on outside air temperature and a reset function curve or be manually adjusted
by the operator. When enabled, the setpoint shall be adjusted above a preset minimum
setpoint upon sensing a domestic hot water demand contact input. When in remote mode,
the control system shall accept a Modbus or 4-20mAdc remote setpoint or firing rate demand
signal from an external Building Automation System (BAS).

D Multiple Boiler Sequence

Multiple boilers shall be modulated in “Unison” (all at the same firing rate). The control
system shall utilize both water temperature and boiler firing rate percent to start and stop the
boilers and shall minimize the total number of boilers in operation. The control system shall
start and stop boilers when the water temperature is outside the adjustable temperature limit
for longer than the adjustable time delay. In order to minimize temperature deviations, the
control system shall start and stop the next boiler when the “lead” boiler is at an adjustable
firing rate limit for longer than the adjustable time delay. The control system shall monitor
both boiler lockout and limit circuits to automatically skip over those boilers that are powered
down for maintenance, tripped or otherwise will not start. When rotation is enabled the lead
boiler shall automatically rotate every 1 to 168 hours. The boiler shall be run at low fire for
warm-up for a preset low fire hold time. When enabled, warm weather shut down control
logic shall prevent boiler operation.

E User Interface

A panel front-mounted English language, two line, sixteen character LCD message display
shall be provided to display numeric data, startup and shutdown sequence status, alarm,
system diagnostic, first-out messages and boiler histor ic al inf orm at ion. Histor ical i nf ormation
shall include the last ten lockout and alarm conditions, number of boiler cycles, boiler hours

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