Summary: There is an issue with the default hydraulic parameters when setting up a new calculation option, which can lead to erroneous fire flow results. The hydraulic parameter “Use Linear Interpolation for Multipoint Pumps?” should default to "True" instead of "False".

Detailed description: When setting up a new calculation option from scratch, the hydraulic parameter “Use Linear Interpolation for Multipoint Pumps?” defaults to “False”. We have found that this parameter yields erroneous Available Fire Flow (AFF) results, and needs to be set to “True” to provide reliable AFF results that would align with an equivalent Hydraulic Only run’s output.

Recommendation: When generating a new calculation option, the default parameter for “Use Linear Interpolation for Multipoint Pumps?” should be set to “True”.

Rationale:

a) The results are consistent with equivalent Hydraulic Only runs, where fire flow demands are applied to the nodes.

b) When modelling existing systems, granular information about pump curves is nowadays more readily available, such that an approximation using a quadratic equation is not necessary. Using a linear interpolation between the available datapoints would better ensure that the pump curves are applied as intended and inputted.

c) Individuals new to modeling might not understand the need to pay attention to these parameters when setting up their calculation options. The default settings would result in them reporting erroneous results.