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Installation & Operation Manual
52
11 Operating information
Ramp delay
For systems with lower flow, the SMART SYSTEM can limit the
firing rate (when enabled) when a space heating call for heat
starts, or when switching from a DHW call for heat to a space
heating call for heat. There are six (6) limits that can be
programmed, as well as six (6) time intervals corresponding to
each limit. The sixth limit will also limit the firing rate for the
rest of the call for heat.
Gradient limiting
If during operation of the boiler the outlet water temperature is
rising too quickly, the control will reduce the firing rate to its
lowest setting.
Outdoor air reset
With the outdoor air sensor connected, the control module will
calculate the set point based on the programmed reset curve.
The installer can change the slope of the reset curve by several
adjustable parameters. The user can limit the maximum set
point for the system using the space heating set point.
Boost function
If outdoor air reset is active, and a space heating demand has
been active continuously for a set period of time (time
adjustable by installer) and there has been no DHW demands,
the control will increase the set point by a fixed number of
degrees (adjustable by installer). This process will continue
until the space heating demand ends, the set point reaches the
programmed set point or a maximum of 20 increases has
occurred. Once the system heat demand is satisfied, the set
point will revert to the value determined by the reset curve.
Night setback
The controller may be programmed to reduce the space heating
set point during a certain time each day. A start and stop time
can be programmed for each day of the week.
Flame current support
To prevent nuisance shutdowns when the boiler is firing at
minimum rates, the control will increase the firing rate when the
flame signal drops too low.
Protection features
Outlet temperature, flue temperature, and
temperature rise limiting
The outlet temperature is monitored by the boiler outlet
temperature sensor. When the outlet temperature exceeds
185°F, the unit will reduce the fan speed. If the outlet water
temperature exceeds 195°F the control will shut the unit down
until it cools off.
The control module monitors the flue temperature by a sensor
located in the flue exhaust. If the flue temperature exceeds
215°F the control will reduce the maximum fan speed. If the
flue temperature exceeds 240°F the control will shut the unit
down. The unit will restart automatically once the flue
temperature drops 25°F and the minimum off time has expired.
The control monitors the temperature difference between the
inlet and the outlet sensor. If this difference exceeds 55°F the
control will reduce the fan speed. If the temperature difference
exceeds 60°F the control will shut the unit down. The unit will
restart automatically once the temperature difference has
dropped below 55°F and the minimum off time has expired.
Freeze protection
DO NOT install the boiler in a room likely to freeze.
The following integral feature of the SMART SYSTEM control
module provides some protection for the boiler only -- not for
the system.
• The SMART SYSTEM control module provides
freeze-up protection as follows when the boiler
water temperature drops below 45°F:
• Below 45°F, the boiler and system pumps operate
constantly.
• Below 37°F, the boiler turns on.
• Boiler and pumps turn off if boiler water
temperature rises above 45°F.
This feature of the SMART SYSTEM control
module does not eliminate the possibility of
freezing. The installation must still use
recognized design, installation and
maintenance practice to prevent freeze
potential for the boiler and system.
ƽ CAUTION