BOM & Running Cost lists a refrigeration system's equipment and pipework as quantities, and counts what the plant costs to run: its electricity, and the refrigerant bought to replace what leaks.
- 1
Choose the system in System. Kelvin fills the page from its latest equipment selection, refrigerant charge and energy analysis, and Calculated from names each record or says which is missing.
- 2
Enter Refrigerant cost per kilogram, and set Annual leak rate to the share of the charge you expect the plant to lose each year.
- 3
Set Period to the number of years to count the running cost over.
- 4
Check Equipment BOM: correct a quantity, remove a line, or add one with Add equipment line.
- 5
Check Pipework BOM: change a length, tick or clear the insulation under a pipe, or add one with Add pipe item.
- 6
Name the record in Name and choose Save.
Where the figures come from
- Refrigerant charge comes from the system's latest refrigerant charge calculation, and Annual energy cost from its most recently updated energy analysis. Both stay editable, and the line under each says where it came from or that you edited it.
- Equipment BOM lists the latest equipment selection's models and quantities, grouped by type, coolroom and suction group.
- Pipework BOM comes from the refrigerant charge's pipe schedule: each pipe size and line totalled, with its design pressure, outside diameter and wall, and how much of it is riser.
- Pipe is counted in whole pieces: 5 m for CO₂ and 6 m for other refrigerants, unless you change a line's piece length.
- Each pipe carries its insulation on a line beneath it: on or off, its wall thickness and the matching part number. Imported suction lines start insulated, and so do liquid lines on CO₂; other lines start without.
- With no equipment selection or charge saved, those lists start empty, and you add lines by hand. A pipe added by hand takes its outside diameter and wall from Kelvin's built-in tube table once you choose its nominal size; its design pressure stays unknown.
The running cost
Running cost sets out four figures, each with its working:
- Annual energy cost, from the energy analysis or as you entered it.
- Refrigerant leaks: the charge × the leak rate × the price per kilogram.
- Annual running cost: the two added together.
- The running cost over the period: the annual figure × the years, undiscounted.
If the energy analysis it came from has months whose cycle didn't solve, its annual cost is a lower bound, and the running cost says so too.
What this station doesn't do
It holds no prices for equipment or pipework, no labour and no capital cost. The bill of materials is quantities only, for you to price. The only money on the page is the running cost, and that isn't discounted.
Saved records
Save stores the BOM and running cost against the system. Saved records are listed under Saved; choose one to open it exactly as it was saved, without importing later changes to the equipment, charge or energy. Once one is open, the button reads Update, and the version it replaces stays in its history.
Note
When you change the system while this page is open, that system's most recently saved record opens, if it has one.