Technical Drawing

BURNHAM COMMERCIAL 27 February 2008
MPC Multiple Pass Commercial Boiler – Suggested Specifications
Heating, Ventilating and Air Conditioning
15500-5
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 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 historical information. Historical information shall include the last ten
lockout and alarm conditions, number of boiler cycles, boiler hours and last ten low boiler return
temperature events. When boiler return water temperature is below a minimum setpoint a low tem-
perature events shall be stored with time, date, “lowest temperature for event” and “duration below
setpoint” data. A panel mounted red alarm light shall annunciate alarm messages. Alarm conditions
requiring a manual reset shall be annunciated by a flashing red light. At a minimum, the boiler sys-
tem shall display the following:
1. Numeric Display with Engineering Units:
a. Boiler Supply Water Temperature
b. Boiler Return Water Temperature
c. Remote System Temperature (when required by contract drawings)
d. Outside Air Temperature (when required by contract drawings)
e. Firing Rate %
f. Boiler Temperature Setpoint
g. Mixing Valve % (when required by contract drawings)