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Hi, My system has a cooling tower that provides condenser water to a hydronic economizer. When the outside air temperatures below 17°C the chilled water from the demand side of the hydronic economizer is fed into the chilled water demand loop(cooling coils and radiant slabs). When the outside air temperature exceeds 17°C, the hydronic economizer is shut and an air cooled gas heat pump feeds the chilled water demand loop. The aircooled gas heat pump also feeds the hot water demand loop (heating coils and radiant slabs).

Based on this question, I used a ChillerHeater:Absorption:DirectFired component to model the air-cooled gas heat pump. And based on this question, I tried overriding the non-integrated hydronic economizer with the ChillerHeater component.

I still get the following severe errors:

   ** Severe  ** SetComponentFlowRate: trapped plant loop index = 0, check component with inlet node named=HP1_COND_IN
   ** Severe  ** GetDensityGlycol: data not found in input for requested glycol "", called from: CalcGasAbsorberChillerModel
   **  Fatal  ** Program terminates due to preceding condition.

Since the ChillerHeater component is air cooled, the Condenser inlet (HP1_COND_IN) and outlet nodes (HP1_COND_OUT) are outdoor air nodes. So, I am confused by this error. I have two questions:

1. Even before I use an EMS code to control the plant components, I am not sure if I am using the air cooled ChillerHeater component correctly. Are there any example files for this component that I can refer to?

2. Does the override feature for the hydronic economizer work the same way for a chiller component and an aircooled chillerheater component?

Any help is appreciated.

Thank you, Raghu

Hi, My system has a cooling tower that provides condenser water to a hydronic economizer. When the outside air temperatures below 17°C the chilled water from the demand side of the hydronic economizer is fed into the chilled water demand loop(cooling coils and radiant slabs). When the outside air temperature exceeds 17°C, the hydronic economizer is shut and an air cooled gas heat pump feeds the chilled water demand loop. The aircooled gas heat pump also feeds the hot water demand loop (heating coils and radiant slabs).

Based on this question, I used a ChillerHeater:Absorption:DirectFired component to model the air-cooled gas heat pump. And based on this question, I tried overriding the non-integrated hydronic economizer with the ChillerHeater component.

I still get the following severe errors:

   ** Severe  ** SetComponentFlowRate: trapped plant loop index = 0, check As the (air-cooled) ChillerHeater:Absorption:DirectFired component with does not have a condenser water loop, the condenser side inlet node named=HP1_COND_IN
   ** Severe  ** GetDensityGlycol: data not found in input for requested glycol "", called from: CalcGasAbsorberChillerModel
   **  Fatal  ** Program terminates due to preceding condition.

Since the ChillerHeater component is air cooled, the Condenser inlet (HP1_COND_IN) and outlet nodes (HP1_COND_OUT) are outdoor air nodes. So, I am confused by this error. I have two questions:

1. Even before I use an EMS code to control the plant components, were modeled as outdoorair:nodes. For the hydronic economizer (HeatExchanger:FluidToFluid component), I am not sure if I am using the air cooled ChillerHeater component correctly. Are there any example files for this component that I can refer to?

2. Does the override feature for the hydronic economizer work the same way for a chiller component and what node name should be used in the field "Component Override Loop Demand Side Inlet Node Name". This is similar to this question but I do no see an aircooled chillerheater component?

Any help is appreciated.

Thank you, Raghu