Plant checks the chillers or boilers on one circuit against the load Circuits worked out for it. The plant is saved on the circuit itself, so the load and the capacity it's judged against always belong to the same circuit.
Enter the plant
- 1
Under Circuit, choose the circuit this plant serves. A project with only one circuit has it chosen already.
- 2
Under Plant units, choose Add a unit for each chiller or boiler. Enter its Capacity at this circuit's water temperatures and design ambient, and the Source it was read from.
- 3
If the maker states the unit's lowest steady output, enter it as Min. turndown. Left blank, that unit isn't checked against a turndown.
- 4
Under Redundancy, choose N+1 if the load must still be met with the largest unit out of service.
- 5
Read Sizing and Staging, then choose Save plant.
Sizing
The load is the circuit's total from Circuits, diversity included, worked out again from the circuit as saved. Sizing sets the Installed capacity, the sum of the capacities entered, against it, and gives the Margin against the load as spare or short.
- Capacity reads Meets the load when the installed capacity is at or above the design load, and Undersized when it isn't, with the shortfall.
- Redundancy says whether the load is still met with the largest unit out. It's reported either way: with N+1 chosen a shortfall is a failure, and with None the same N+1 not met is a note, for information.
Staging
Staging brings the units on smallest first. Each stage covers the loads between the capacity of the stage before it and its own, and Min. part load is the fraction of its capacity at the bottom of that band: the lowest the running units are asked to work before the stage below takes over. The first stage's figure is its unit's own stated turndown, where it has one.
- Held: every running unit holds that part load.
- Below turndown: a running unit's stated turndown is above it, so that unit can't hold the bottom of the band. The stages must overlap, or the unit will cycle.
- Not stated: no running unit states a turndown, so the stage isn't checked.
Kelvin takes the running units as sharing the load equally, so each sits at the same fraction of its own capacity.
Limits
- Kelvin holds no plant catalogue and doesn't rate a machine itself. Every capacity is your figure from the selection at this circuit's conditions, and the plant isn't saved until each unit names its source.
- Plant judges capacity, redundancy and turndown only. It doesn't model the plant's efficiency or energy use.
- Until Circuits can work out the circuit's load, there's nothing to size against, and Sizing says so. A unit with no capacity entered holds the sizing back until it has one.
- The version a save replaces stays in the circuit's history.