Hi,

I set the radiant floor heating design capacity at specific value, say 1,000 W, but when I check the "Zone Radiant HVAC Heating Rate" the output is 2,000 W. I tried other values, 500, 300 and the output is always twice of the input.

=== IDF === ZoneHVAC:LowTemperatureRadiant:VariableFlow, Zone HVAC Low Temperature Radiant Variable Flow 1, !- Name Always On Discrete, !- Availability Schedule Name Thermal Zone 1, !- Zone Name Zone HVAC Low Temperature Radiant Variable Flow 1Floors, !- Surface Name or Radiant Surface Group Name ConvectionOnly, !- Fluid to Radiant Surface Heat Transfer Model 0.012, !- Hydronic Tubing Inside Diameter {m} 0.016, !- Hydronic Tubing Outside Diameter {m} Autosize, !- Hydronic Tubing Length {m} 0.35, !- Hydronic Tubing Conductivity {W/m-K} MeanRadiantTemperature, !- Temperature Control Type ZeroFlowPower, !- Setpoint Control Type HeatingDesignCapacity, !- Heating Design Capacity Method 1000, !- Heating Design Capacity {W} , !- Heating Design Capacity Per Floor Area {W/m2} , !- Fraction of Autosized Heating Design Capacity