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Setpoint Temp — This is the lowest boiler operating temperature that the boiler will maintain when the outside air temperature is at the O.A. Max. This setting is a Changeable Point from the Command Display.
Calculated Set Point — The water temperature as adjusted by the optional outdoor air reset function used on a heating boiler only. If no outdoor reset function is used, this displays the same temperature as the set point. The Outdoor Air Reset function is not available on a water heater application.
These functions are shown in the screens of the Command Display. Where noted, these settings are changeable from the Command Display to configure boiler operation to the building heat load and weather conditions in a specific geographic area.
MULTIPLE APPLIANCE
INSTALLATIONS
SEQUENCING BOX
REMOTE DISPLAY MOUNTING
CLOSED VIEW | COMPONENT |
| LOCATIONS |
FIG. 58 Sequencer Control Panel
SEQUENCING OPTIONS
The sequencer is supplied as a separate control enclosure that is connected to the multiple appliances via an
NOTE:
Separate sequencers are required to control multiple boilers and water heaters.
1.First On - First Off — This is a lead/lag control functionality. The sequencing of the boilers or water heaters is based on the total loop load with
added units | being | brought | on | when | the units | ||||
that are running are at 100% and | the loop | load is | |||||||
not | being | met. Boilers | or water | heaters | are | turned | |||
off | when | the | loop | load | falls | and | the first boiler or |
water heater on is at minimum load.
2.First On - Last Off — This is a simple first on/last off without rotation of the lead boiler or water heater.
3.Efficiency Optimized — The lead/lag will be based on first on/first off lead/lag. The overall efficiency will be optimized to run the boilers or water heaters at their highest efficiency. Highest efficiency occurs at the minimum loading for each boiler or water heater. Therefore, this option will add boilers or water heaters when the load reaches a
point where the next boiler or water heater can run at minimum load.
4.Efficiency Optimized with Time Equalization —
This is the same as “Efficiency Optimized” but the lead/lag is based on boiler or water heater run times. The boilers or water heaters will be sequenced to equalize run times to within approximately a 24 hour time period. If no opportunity is given to cycle, the control will not interrupt action to equalize runtime.
5.None — This is the default for any boiler or water heater control which has not purchased one of the Sequencing Option Packages.
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