For network iterations two kinds of convergence criteria are applied: the residuals and the change in the solution must be both small enough.
For the mass and energy flow residuals 
![]() and
 and
![]() are calculated as specified in Equations (380) and
(381) with
 are calculated as specified in Equations (380) and
(381) with ![]() and
 and 
![]() equal to the mass flow (unit of
mass/unit of time) and the energy flow (unit of energy/unit of time). For the
element equation
 equal to the mass flow (unit of
mass/unit of time) and the energy flow (unit of energy/unit of time). For the
element equation  
![]() is taken to be 1 (the element
equation is dimensionless) and
 is taken to be 1 (the element
equation is dimensionless) and 
![]() is calculated based on the
element equation residuals. The residual check amounts to
 is calculated based on the
element equation residuals. The residual check amounts to 
| (390) | 
where ![]() takes the value
 takes the value ![]() ,
, ![]() and
 and ![]() for the energy
balance, mass balance and element equation, respectively.
 for the energy
balance, mass balance and element equation, respectively.
In the same way the maximum change in solution in network iteration i
![]() is compared with the maximum change in the solution
since the start of the network iterations, i.e. the solution at the end of
iteration i minus the solution at the beginning of the increment(before
network iteration 1). This is done separately for the temperature, the mass
flow, the pressure and the geometry. It amounts to the equation:
 is compared with the maximum change in the solution
since the start of the network iterations, i.e. the solution at the end of
iteration i minus the solution at the beginning of the increment(before
network iteration 1). This is done separately for the temperature, the mass
flow, the pressure and the geometry. It amounts to the equation:
| (391) | 
where ![]() takes the value
 takes the value ![]() ,
, ![]() ,
, ![]() and
 and ![]() for
the temperature, the mass flow, the pressure and the geometry,
respectively.
 for
the temperature, the mass flow, the pressure and the geometry,
respectively. 
The parameters ![]() ,
, ![]() ,
, ![]() ,
, ![]() ,
, ![]() ,
, ![]() and
 and
![]() can be changed using the *CONTROLS,PARAMETERS=NETWORK card.
 can be changed using the *CONTROLS,PARAMETERS=NETWORK card.
Both criteria are important. A convergent solution with divergent residuals points to a local minimum, convergent residuals with a divergent solution point to a singular equation system (i.e. infinitely many solutions).