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After spending some time with a grocery store model, it seems there is an issue with how the Refrigeration:Condenser:AirCooled object is controlling the condenser fans. This object has very few inputs to determine power and capacity, just the rated fan power and a linear curve for condenser capacity. If it is cold outside, everything operates as it should, the fan speed drops and the condensing temperature is set constant at the minimum specified in the input. When the outdoor air temperature rises above that minimum condensing temperature, the program forces the fans to run at 100% all the time. Instead these fans should operate to maintain a dT between the outdoor air temperature and condensing temperature.

For example, if it is 90F outside, the condensing temperature should be 100F if we are maintaining a 10F dT. instead, I am seeing the dT at 3-5F because the fans are running flat out, using way more energy than they should. This isn't a big deal for colder climates, but when I move this model to Miami, the condenser fans run at essentially 100% all year.

Looking at the [Engineering Reference], the condensing temperature is determined by a variable called Hrej divided by HrejRated rather than a constant dT when the outside air temp is warm. The system then thinks the condenser fans need to run at 100% to maintain this low condensing temperature.

So far, I have experimented with the linear curve coefficient, min/max values, speed control type, and minimum fan speed. Please let me know if I am missing something.

Here is the % capacity by outside air temperature:

and the dT between outside air temp and condensing temperature:

After spending some time with a grocery store model, it seems there is an issue with how the Refrigeration:Condenser:AirCooled object is controlling the condenser fans. This object has very few inputs to determine power and capacity, just the rated fan power and a linear curve for condenser capacity. If it is cold outside, everything operates as it should, the fan speed drops and the condensing temperature is set constant at the minimum specified in the input. When the outdoor air temperature rises above that minimum condensing temperature, the program forces the fans to run at 100% all the time. Instead these fans should operate to maintain a dT between the outdoor air temperature and condensing temperature.

For example, if it is 90F outside, the condensing temperature should be 100F if we are maintaining a 10F dT. instead, I am seeing the dT at 3-5F because the fans are running flat out, using way more energy than they should. This isn't a big deal for colder climates, but when I move this model to Miami, the condenser fans run at essentially 100% all year.

Looking at the [Engineering Reference], the condensing temperature is determined by a variable called Hrej divided by HrejRated rather than a constant dT when the outside air temp is warm. The system then thinks the condenser fans need to run at 100% to maintain this low condensing temperature.

So far, I have experimented with the linear curve coefficient, min/max values, speed control type, and minimum fan speed. Please let me know if I am missing something.

Here is the % capacity by outside air temperature:

and the dT between outside air temp and condensing temperature: