LAARS SC 12 - Install and Operating Manual - Manual (Page 24)

Page 24 LAARS Heating Systems
SHUTDOWN
• This feature allows the user to shutdown all Stage Outputs on the SC from a remote location.
• A typical use of this feature would be to turn off all boiler stages when the outdoor temperature rises above a certain point. The
outdoor thermostat would close a dry contact and the SC would then turn all the Stage Outputs off until the outdoor temperature
fell and heat was once again required.
• On systems where the DHW input is used, a call for domestic hot water will override a Shutdown. During the DHW call, the
water temperature will be maintained at 200°F. When the call for DHW is removed, the SC will then resume Shutdown.
• To enable the Shutdown, the Setback/Shutdown (Stb) control setting must be set to zero. Zero is the default value. Any
nonzero number will enable Setback Stb (see below).
• When the Shutdown is activated, all active Stage Outputs are immediately turned off. However, the System Output (and the
individual Pump Outputs on the SC-6P) will remain activated for the period of time set by the System Delay Sd (see pg. 22).
• For wiring a remote Shutdown, see pg. 6.
SETBACK
• This feature allows a user to temporarily reduce the Set Point or Calculated water temperature.
• A
are sleeping. An external time clock could be programmed to close a dry contact to reduce the water temperature during these
times. When the time clock contacts open, then the SC will resume circulating the higher temperature water.
• To enable the Setback, the Setback/Shutdown (Stb) control setting must be set to the desired number of Setback degrees. If the
default Setback/Shutdown value of 0 is not changed, the SC will shutdown all stages when Input terminals 7 and 77 8 are shorted.
• On systems where the DHW input is used, a call for DHW will override the Setback. Stb During the DHW call, the water
temperature will be maintained at 200°F. When the call for DHW is removed, the SC will return to the Setback Stb Set Point
temperature.
• For wiring a remote Setback, see pg. 6.
PROVE
• This feature is provided to check if system components are running properly.
• The PROVE input terminals must be continuous for any Stage Output to be active. If the PROVE PROVE PROVE inputs are opened when Stage PROVE PROVE
Outputs are active, then they will immediately de-energize (and the individual Pump Outputs on the SC-6P will de-energize after
the System Delay time).
• The Prove function is the default value for Input terminals 9 and 10. However, the same input terminals can be programmed to
provide a DHW input. To check or change the function of these terminals, see pgs. 6 and 8.
• The Set Point or Calculated water temperature will display PrF to indicate when stages are not being energized because the
Prove signal is not made.
• The PROVE input does not affect the status of the System Output. PROVE PROVE
• A typical use of this feature is to check for fl ow before fi ring any boiler stages. When there is a call for heat, the System Output
activates the system pump starter. When the pump establishes fl ow, a fl ow switch shorts together the PROVE input terminals. PROVE PROVE
The SC then adds Stage Outputs as required to hold the temperature set point.
• Another typical application is to check the combustion air damper. When there is a call for output, the System Output can be
wired to open a combustion air damper. An end switch on the damper can then be wired back to the PROVE input terminals. The PROVE PROVE
SC then activates Stage Outputs as required.
• The PROVE input must be shorted for Stage Outputs to be activated. When not using the Prove function, the PROVE PROVE PROVE input must PROVE PROVE
be shorted. (The SC is shipped with a jumper to short out the PROVE terminals.) PROVE PROVE
• For wiring the PROVE input, see pg. 6. PROVE PROVE
WARNING
The SC PROVE input can not be used as a safety limit. All equipment must have its own certifi ed limit and safety PROVE PROVE
controls as required by local codes. Any combustion air damper signal or other interlock provided for safety
MUST be wired back to the individual boilers and any other equipment required by code, in addition to being
wired into the SC PROVE terminals. PROVE PROVE