diff --git a/OpenHPL/Data.mo b/OpenHPL/Data.mo
index 4667b6a..6d7d3fb 100644
--- a/OpenHPL/Data.mo
+++ b/OpenHPL/Data.mo
@@ -5,7 +5,7 @@ record Data "Provides a data set of most common used settings"
     annotation (Dialog(enable=false, group = "Constants"));
   parameter Real gamma_air = 1.4 "Ratio of heat capacities at constant pressure (C_p) to constant volume (C_v) for air at STP"
     annotation (Dialog(enable=false, group = "Constants"));
-  parameter SI.Pressure p_a = 1.013e5 "Atmospheric pressure"
+  parameter SI.Pressure p_a = 0 "Default calculation is gauge pressure (set p_a to atmospheric pressure if absolute pressure is required)"
     annotation (Dialog(group = "Constants"));
   parameter SI.MolarMass M_a = 28.97e-3 "Molar mass of air at STP"
     annotation (Dialog(group = "Constants"));
@@ -13,7 +13,7 @@ record Data "Provides a data set of most common used settings"
     annotation (Dialog(group = "Waterway properties"));
   parameter SI.DynamicViscosity mu = 1.3076e-3 "Dynamic viscosity of water at T_0"
     annotation (Dialog(group = "Waterway properties"));
-  parameter SI.Height p_eps = 5e-2 "Pipe roughness height"
+  parameter SI.Height p_eps = 0 "Pipe roughness height (default is smooth pipe)"
     annotation (Dialog(group = "Waterway properties"));
   parameter SI.Compressibility beta = 4.5e-10 "Water compressibility"
     annotation (Dialog(group = "Waterway properties"));
@@ -21,7 +21,7 @@ record Data "Provides a data set of most common used settings"
    annotation (Dialog(group = "Waterway properties"));
   parameter Boolean SteadyState=false "If checked, simulation starts in steady state"
     annotation (choices(checkBox = true), Dialog(group="Initialization"));
-  parameter SI.VolumeFlowRate Vdot_0=19.077 "Initial volume flow rate through the system"
+  parameter SI.VolumeFlowRate Vdot_0 = 0 "Initial volume flow rate through the system"
     annotation (Dialog(group="Initialization"));
   parameter SI.Frequency f_0 = 50 "Initial system frequency"
     annotation (Dialog(group = "Initialization"));