Getting Started Guide: Estimating Variables
The support function Estimate allows the user to guess a value required to initially solve a closed loop steam system, and have it automatically replaced later on when a calculated result becomes available. A common example is the inlet mass flow to the deaerator from the bottom steam header (see the Tutorial step here). This is required in order to solve the mass balance across the bottom header, in order to solve up the sheet. Once the deaerator has been solved (by completing the boiler loop), this value can then be replaced by the calculated result.
A secondary feature of the Estimate function is the ability to automatically catch errors propagating through the sheet by using the estimated value if the actual value contains an error. This includes all default Excel errors such as #VALUE!, #NUM!, #NAME!, #N/A, etc.