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Hello,
I’m currently performing an HVAC analysis for an indoor swimming pool. After modeling a solution using a boiler to heat the supply air, I’m now looking to implement a similar setup using a heat pump.
However, I’ve encountered some limitations with Type143. It doesn't allow me to vary the mass flow rate or define a setpoint temperature for heating control. As a result, the indoor temperature is not regulated properly—leading to supply air temperatures exceeding 100 °C, which is clearly unrealistic.
I don’t have access to the TESS library. Could anyone let me know if it includes components that address this issue, or if there’s another library or method that could help me achieve temperature control and flow regulation with a heat pump?
Best regards,
Henrique Sousa
EllaMae 12/12/2025 7:53 am
@henriquesousa16 Hi Henrique, maybe try a different heat pump model or add a controller to manage the temperature and airflow.
The TESS HVAC library does include some variable-speed heat pump models that vary the compressor speed to maintain a specified outlet temperature, but I don't believe there are any variable-speed heat pump models in the standard library.
If you haven't already, I would connect a thermostat to the heat pump that cycles the heat pump on and off to maintain the indoor temperature within a reasonable range. You can see an example of this in the Examples/HVACTemplates/System2.tpf example project in your main TRNSYS directory (the example uses an air-to-air heat pump, but the connections between the thermostat, heat pump, and conditioned zone will be similar). You may still need to change the air flow rate and/or performance data files you use with Type143 to get reasonable supply air temperature values and temperature control in the space.
Type143's capacity and power are very specific to the data files used with the model. There are some sample files connected to the model by default, but the expectation is that users of Type143 will create their own data files specific to the heat pump they are modeling. There are links to YouTube tutorials that walk through how to understand and create data files for TRNSYS models here ( https://trnsys.com/support/tutorials.php.html ). You may be getting unreasonably high supply air temperatures out of Type143 because the air flow rate and/or zone size are too small for the heating capacities in the performance data files. The TESS HVAC Library includes heat pump models that are similar to Type143, but that use "normalized" data files that are easier to scale to different capacities.
Dear @a_weiss,
Thank you very much for your support.
I'll reach out to my mentor to request access to the library and will try to work with the models available there.
Do you happen to know if the components in the TESS HVAC Library include any way to limit the supply air temperature?
Also, do you have any suggestions for obtaining performance data files for real heat pumps? I've tried searching online and contacting a few suppliers, but I haven't been able to find the detailed data required to build the performance file.
@henriquesousa16 I would check a heat pump manufacturer's website for performance map data. Carrier, Trane, and others usually have performance data published under 'Product Literature' or 'Technical Data' for different models on their websites. Sometimes a Google search for a specific model number is the most productive way to find it.
HenriqueSousa16 Topic starter
12/05/2025 10:38 am
@a_weiss is it possible to use Type143 or Type919 with only one value of air flow rate? I'm asking this because the only HP I found that suits my project has only a single value of 9000 cfm.
The easiest way (I think) to accomplish this is to just repeat the single air flow value twice at the top of the data file (so the first line of the data file would read:
4247.52 4247.52 !Values of Airflow in liters per second [l/s]
), and repeat the data from the first flow rate for the second flow rate. Make sure to also set Parameter 20 of Type143 to 4247.52 l/s.
The other thing you can do is use a single value for air flow rate in the data file, and modify the proforma (the icon for the Type in the Simulation Studio) to allow the minimum number of air flow steps as one. There is a video that walks through how to make proforma modifications here: Changing Cycle or Parameter Limits in a TRNSYS Proforma . Note that this only works if the underlying source code of the Type is also configured to allow the given value for the parameter. In TRNSYS18.06, it looks like the source code for Type143 can accept a minimum of one value for air flow rate, but older versions of TRNSYS may return a parameter value error if you try to set less than two air flow steps in Type143. Again, make sure the value of Parameter 20 matches the heat pump manufacturer data as well.
A_Weiss 12/05/2025 2:13 pm
One note that may help explain/resolve some warning messages: If the air flow value(s) in the data file don't match the value of Parameter 20 exactly, you may get a lot of warnings that Type143 tried to read a value above or below the limits of the data file. If you're only using a single flow rate in the data file, you can safely ignore those warnings. If you're using two air flow rates with the same performance data at both flow rates, you can either ignore the warnings, or you can set the upper and lower flow rates in the data file to some arbitrary high/low values that encompass the flow rate set by Parameter 20 (i.e. 4240 and 4250 l/s, or 0 and 10000 l/s). Since the data at both flow rates are the same, the difference between the upper and lower limits for interpolation doesn't really matter.
HenriqueSousa16 Topic starter
13/05/2025 3:55 pm
@a_weiss Thank you very much! I was able to solve it with your help!
