NOTICE
When system return temperatures
are maintained below the dew point,
condensation will form on the inside of the
boiler jacket causing some internal sheet
metal components to rust.
Low voltage blocking
The blower and gas valve require a minimum amount of voltage
in order to operate properly. If an ignition attempt is made
when the line voltage is temporarily low (such as during a
brownout), the control could enter a manual reset lockout. To
prevent this, the control monitors the voltage and blocks any
heat demands until the voltage returns to an acceptable level.
Installation & Operation Manual
11
Operating information
61
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 (90°C) 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 (102°C) the control will reduce the maximum fan speed.
If the flue temperature exceeds 225°F (107°C) the control will
shut the unit down. The unit will restart automatically once the
flue temperature drops 10°F (6°C) and the minimum off time
has expired.
The control monitors the temperature difference between
the inlet and the outlet sensor. If this difference exceeds 70°F
(39°C) the control will reduce the maximum fan speed. If the
temperature difference exceeds 80°F (44°C) the control will
shut the unit down. The unit will restart automatically once the
temperature difference has dropped below 70°F (39°C) and the
minimum off time has expired.
Night setback
The controller may be programmed to reduce the space heating
and DHW set points during certain times each week. Seven
different start and stop times may be programmed for the space
heating setback and seven start and stop times for the DHW
setback.
Vacation mode
Vacation Mode is used to lower the Space Heat (SH) and/or
DHW set points much like night setback. The set points will
remain lowered until Vacation Mode is disabled. Night setback
will not function when Vacation Mode is enabled.
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.
Neither this feature, the boiler control module, nor the use of
glycol, eliminates the possibility of freezing. The installation
must still use recognized design, installation, and maintenance
practice to prevent freeze potential for the boiler and system.
The Freeze Protection feature will not work if the appliance
does not have power, is locked out, is in shutdown mode, had a
component failure, or is otherwise prevented from firing.
The following integral feature of the boiler control module
provides some protection for the boiler only -- not for the
system.
The boiler control module provides a freeze protection feature
with the following attributes:
• Below an inlet temperature of 45°F, the boiler pump
operates constantly.
• Below an inlet temperature of 37°F, the burner fires.
• Boiler and pumps turn off if boiler water inlet
temperature rises above 45°F.