Kelvin finds each bend and branch in the ductwork you draw, but it doesn't assume a loss coefficient for any of them. You enter each one from your own lookup in the ASHRAE Duct Fitting Database, with the inputs you used, so the coefficient and its citation travel with the network.
- 1
In the Duct plan, choose Select and click a duct run. Fittings found on this run lists each bend and branch on it, and where it is.
- 2
Look the fitting up yourself, and type its coefficient in C.
- 3
Under Referenced to, choose the velocity the coefficient is referenced to: This section, Branch or Main downstream. Kelvin presets it from what the fitting is; change it to match your lookup.
- 4
Under Source, type the fitting code and the inputs you used.
The list appears once the network is compiled from the plan, so choose the network's Role and Air system first. The fitting's loss is C times the velocity pressure at the velocity you chose, and it is added to its segment's drop.
Until a fitting has a coefficient
- A fitting with no coefficient is left out, not guessed. The segment table says how many detected fittings have none, and the notes under the plan name each one.
- A coefficient without its source is refused: the network waits for the citation.
- Give an offset its own coefficient, or give its elbows theirs, not both. Kelvin refuses the pair because it would count the bend twice.
Library rows
When Kelvin's reference library holds fitting rows, Choose a library row instead offers them, and Enter the coefficient instead goes back. Without any, the coefficient is always entered.
In a typed network
On a network entered as a Segment table, choose Add fitting on a segment, then Entered C with its name, coefficient, velocity and source, or Library row.
Note
The network keeps your lookup: the coefficient, the velocity it is referenced to and its citation. When you redraw the ductwork, check each citation's inputs still match the fitting.