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Coil cooling rate results higher than autosize values

asked 2025-10-01 06:36:17 -0500

Thit's avatar

updated 2025-10-01 09:12:44 -0500

Hello everyone, how does Unitary Furnace Heat Cool System auto size cooling capacity? When I observe the result in Cooling rate for each zone, the simulation result is higher than the one in EIO auto size capacity. Is there something I was doing wrong in the model setup, please help me :) Thank you EIO Cooling Rate [W]https://drive.google.com/drive/folder...

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answered 2025-10-02 11:07:18 -0500

The Sizing:Parameters object multiplies the heating/cooling capacities by the heating/cooling sizing factors. Looks like you've got a 1.2 factor on both heating and cooling. Set these to 1 if you don't want oversizing.

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I have changed sizing factor to be 1, but still, it is 1.248 times higher than in EIO Component autosized calculated cooling capacity, so I modified some of curve values (Quadratic and Biquadratic) which is automatically generated values from unitary furnace heat cool template. But the problem is the modified curve values make the system no outdoor air intake.

Thit's avatar Thit  ( 2025-10-09 05:18:45 -0500 )edit
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answered 2025-10-09 07:44:09 -0500

The information above shows the zone and system sizing information. There is also "Component Sizing Information" information on coil sizing below this section in the eio file. Also look at the Capacity as a Function of Temperature performance curve for your coil. If the operating conditions (e.g., outdoor temperature and indoor wet-bulb temperature) are different than when the coil sized the capacity multiplier (the curve result) might be different. You can report all of this information using Output:Variable reports listed in the rdd file.

From eio file:

Component Sizing Information, COIL:COOLING:WATERTOAIRHEATPUMP:EQUATIONFIT, MAIN FLOOR WAHP COOLING COIL, Design Size Rated Total Cooling Capacity [W], 5725.81490

From rdd file:

Output:Variable,"your coil name",Cooling Coil Total Cooling Rate,hourly; !- HVAC Average [W]
Output:Variable,"your coil CAPFT curve name",Performance Curve Output Value,hourly; !- HVAC Average []

Output:Variable,"your coil INLET NODE name",System Node Temperature,hourly; !- HVAC Average [C]
Output:Variable,"your coil INLET NODE name",System Node Wetbulb Temperature,hourly; !- HVAC Average [C]
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Asked: 2025-10-01 06:36:17 -0500

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