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Xii. Operation
A. The Alpine (ALP) boiler uses a microprocessor based
Honeywell control, known as a “MCBA”, to manage
all boiler functions including ame supervision and
modulation. Two set point or “target” boiler supply
temperatures are stored in the MCBA’s memory;
one for space heating and one for domestic water
production. If an outdoor temperature sensor is
connected to the boiler, the space heating supply set
point will automatically adjust downwards as the
outdoor temperature increases. For more information
on this feature see the discussion on boiler water reset
below.
The MCBA modulates the boiler input by varying the
fan speed. As the fan speed increases, so does the
amount of gas drawn into the blower. As a result, a
fairly constant air-fuel ratio is maintained across all
inputs.
The MCBA determines the input needed by looking
at both current and recent differences between the
supply temperature and the set point temperature.
As the supply temperature approaches the set point
temperature, the fan will slow down and the input drop.
Depending on the model boiler, the minimum input
is between 1/3 (high altitude) and 1/5 (sea level) of
maximum input.
The MCBA also monitors boiler return and ue
temperatures. In addition, all other safety controls,
including the low water cut-off and safety limit, are
connected into the MCBA. The MCBA uses input from
all of these controls to either shut down the boiler when
an unsafe condition exists or, in some cases, to correct
the problem.
B. The display panel has three primary modes of
operation. These are:
1. Standby Mode – Displays boiler’s current status.
This is the default operating mode.
2. Parameter Mode – Used to change control settings
3. Information Mode – Displays boiler operating
temperatures
Under normal conditions, the boiler is in standby mode
and the display looks like that shown in Figure 49. The
three digits to the right of the decimal point are the
boiler’s supply temperature. The digit to the left of the
decimal point is the boiler’s status code. A list of status
codes, and their meanings, is shown in Table 26.
Figure 50 is a map of the menu structure for the control
panel. Push the mode key to move from one mode
to the next. As you change modes, the mode you are
entering is shown on the display:
a. “PArA” for Parameter Mode
b. “Info” for Information Mode
c. “Stby” for Standby Mode. Upon entering
standby mode, “Stby” will briey appear on
the display and then the display will show the
boiler’s status along with the supply temperature
(Figure 49).
The control will return to standby mode from any
other mode if no key is pressed for 20 minutes.
Figure 49: normal Display in Standby Mode
C. In standby mode, it is possible to view both the
heating supply set point temperature and the “domestic
hot water reference set point”. The “domestic hot
water reference set point” plus 45°F equals the boiler
supply set point when it is responding to a call from
the indirect water zone. It is not the actual domestic
hot water set point. The Alpine (ALP) is designed
for use with a storage type indirect water heater such
as the Alliance SL™. The domestic water set point
is controlled by the thermostat on the indirect water
heater. The “default domestic water reference set point”
is 135°F and target boiler supply temperature when
responding to a call from the indirect water heater is
therefore 180°F (135°F +45°F). The default heating
supply set point (parameter 4) is 180°F.
In standby mode it is also possible to turn on or off
either the heating or domestic water zone. There is
normally no reason to turn off either of these zones and
doing so is not recommended.
WaRning
Pushing and holding the “+” while in Standby
Mode will prevent the boiler from responding to
a call for heat. Pushing and holding the “-” while
in Standby Mode will prevent the boiler from
responding to a call for domestic water. if this
happens, “cOFF” or “dOFF” will appear on the
display. To turn back on the heating function,
press and hold “+” until “c” and the set point
temperature appears on the display. To turn back
on the domestic water function, press and hold “-”
until “d” and the set point temperature appears on
the display. after pressing any keys, and before
leaving the installation, verify that the boiler res
in response to a call for heat and domestic water.

I. Factory Preset Boiler Operating Parameters

(See Table 25 for Parameter Descriptions)