Crown Boiler Phantom X series, Installation And Operating Instructions Manual, Page: 78 / 136

78
X. Operation
A. Overview
1. R7910 Controller
The R7910 Controller (Control) contains features
and capabilities which help improve heating system
operation, and efficiency. By including unique
capabilities, the Control can do more, with less field
wiring, and fewer aftermarket controls and components
– improving the operation of both new and replacement
boiler installations.
2. Advanced Touch Screen Display
Home Screen
Boiler status and setup selections are available from
an easy to use, dual color, LCD Touch Screen Display.
Over one hundred helpful information screens are
provided to explain status information and setup
functions. In the event of a fault condition the user
is guided by “blinking” touch buttons to Help screens
that explain the problem cause and corrective action.
Operation evaluation and problem-solving is enhanced
by historical capability including graphic trends,
lockout history records as well as boiler and circulator
cycle counts and run time hours.
3. Advanced Modulating Control
The Control modulates the boiler input by varying
the fan speed. As the fan speed increases, so does the
amount of fuel gas drawn into the blower. As a result,
a fairly constant air-fuel ratio is maintained across all
inputs. The Control determines the input needed by
looking at both current and recent differences between
the measured temperature and the setpoint temperature.
As the measured temperature approaches the setpoint
temperature, the fan will slow down and the input will
drop. The Control also utilizes boiler return water and
flue gas temperatures to adjust fan speed.
4. HeatMatch
TM
Software
When the boiler is installed with a Crown PN 3501505
Zone Control Panel (Zone Control) into a multiple zone
home the Control uses a patent pending HeatMatch
Software to improve home comfort, increase component
life and save energy. The R7910 Controller with the
Zone Control detects active (turned “on”) zones, totals
btu/hrs expected and limits the boiler firing rate to
“match” actual home demand. Instead of simply firing
to 100% in response to a cold supply water temperature
the Control combines heat matching with supply water
temperature control. The result is longer run times,
dramatic reduction in boiler excessive cycling and
higher operating efficiency. Avoiding extra cycling
saves customer fuel dollars (pre and post purge sends
heat up stack) and saves wear and tear on the boiler.
Lowering the boiler’s firing rate saves fuel dollars by
increasing the amount of flue gas condensation, always
the goal of condensing boiler installations.
5. Built-in Safety Control
The Control includes safety controls designed to ensure
safe and reliable operation. In addition to flame safety
controls the Control includes supply water temperature,
differential water temperature, and stack temperature
safety limits and stepped modulation responses.
Boiler modulation is adjusted when required to help
avoid loss of boiler operation due to exceeding limits.
Additionally, the Control accepts the field installation
of optional auxiliary safety limits.
6. Outdoor Air Reset
When selected the modulation rate setpoint is
automatically adjusted based on outside air temperature,
time of day and length of demand (boost) settings.
Outdoor air “reset” setpoint saves fuel by adjusting
the water temperature of a heating boiler lower as the
outside air temperature increases.
7. Warm Weather Shutdown (WWSD)
Some boilers are used primarily for heating buildings,
and the boilers can be automatically shutdown when
the outdoor air temperature is warm. When outside air
temperature is above the WWSD setpoint, this function
will shut down the boiler and system pump.
8. Energy Management System (EMS) Interface
The control accepts a 4-20mAdc input from the EMS
system for either direct modulation rate or setpoint.
A factory configured RS485 Modbus interface is
available for Energy Management System (EMS)
monitoring when not used for Multiple Boiler
Sequencer Peer-To-Peer Network. Consult factory
if this interface must be used in addition to the boiler
Peer-to-Peer Network.
9. Circulator Control
The Control may be used to sequence the domestic
hot water, boiler and system circulators. Service rated
relay outputs are wired to a line voltage terminal block
for easy field connection. Simple parameter selections
allow all three pumps to respond properly to various
hydronic piping arrangements including either a boiler
or primary piped indirect water heater. Circulators
are automatically run for a 20 second exercise period
after not being used for longer than 7 days. Circulator
exercise helps prevent pump rotor seizing.
10. Multiple Boiler Sequencer Peer-To-Peer
Network
The Control includes state-of-the-art modulating lead-
lag sequencer for up to eight (8) boilers capable of auto
rotation, outdoor reset and peer-to-peer communication.