Technical Drawing

BURNHAM COMMERCIAL 27 February 2008
MPC Multiple Pass Commercial Boiler – Suggested Specifications
Heating, Ventilating and Air Conditioning
15500-7
h. High Supply Temperature
i. Supply Temperature Sensor Fault
j. Return Temperature Sensor Fault
k. Outside Air Temperature Sensor Fault
l. Remote System Temperature Sensor Fault
m. Remote Input Signal Fault
n. Modbus Communication Fault
o. Memory Fault
F Flame Safeguard (FSG)
An industrial duty microprocessor-based FSG shall provide: safety interlocks, flame monitoring pro-
tection and timed sequences. Sequences shall include forced draft fan start and stop, furnace purge,
burner light-off and shutdown and post-purge. FSG components shall be fully integrated for auto-
matic sequencing of light-off and shutdown.
G Boiler Pump Sequence
Include primary water pump control to allow boiler warm-up to the return water temperature before
the boiler start; continue water flow for an adjustable cool down period after the boiler has stopped;
and ensure water is always moving past the remote system temperature sensor even after the last
boiler has been stopped. The pump shall immediately stop if any trips occur during pre-purge, pilot,
or main flame trial for ignition.
H Flue Gas Condensate Protection
Include alarms and control logic to help prevent corrosion in the boiler due to sustained flue gas con-
densation. These features become increasingly important as we add energy savings modulation and
outdoor air reset functions. Provide a 4-20mAdc, 3 way mixing valve control output based on PID
control, measured boiler return temperature and minimum return temperature setpoint or measured
boiler return and supply temperature difference and differential setpoint. If the boiler return water
temperature drops below setpoint or the differential temperature is excessive the valve shall open to
allow hot boiler supply water to blend with cold return water temperature. The valve repositions to-
ward 0% recirculation after return water temperature increases above setpoint. Low boiler return wa-
ter temperature shall be alarmed using an alarm message, indicating light and an alarm contact out-
put. Excessively low boiler return temperature events shall be stored with boiler historical data.
I Mixing Valve (when required by contract drawings)
In order to prevent low return water temperature, provide an electric actuated three-way mixing valve
with a 4-20 mAdc input control signal and slow (1 minute) travel time for each boiler. If the boiler
return water temperature is below 130 ° F (adjustable), the valve shall slowly jog closed causing