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Re: [TRNSYS-users] Type 941 air-to-water heat pump, floor heating



László,

  The most common problem when dealing with non convergence is too long a timestep or not enough thermal capacitance in the liquid loop. I would recommend running with no more than a 5 minute time step and that you estimate the volume of liquid in your floor heating loop. Make sure that you have piping or a buffer tank whose volume is at least as large as the larger of the estimated volume and the amount of liquid that the pump can push in one time step.

kind regards,

 David



On 08/30/2021 08:01, Gergely László Zsolt via TRNSYS-users wrote:
Dear All,

I am trying to simulate Type 941 air-to-water heat pump system (file Multizone_AWHP_V2_H&C_08.30_BP.idf), directly connected to floor heating and slab cooling, however the model does not work for some reasons. Trnsys message 441 comes up, saying that some listed inputs have not coverged during the simulation. It seems to occur escpecially in case of heating - the simulation does not even finish. However, in case of cooling the model seems to work - starting with June the simulation goes on until the first periods of heating. 

Do you have any ideas what the problem could be and how to solve it? 
Would really appreciate it!

Also, it is strange that it is the case for Budapest weather data, or all other that needs heating a lot. In case of Sydney weather, it seems to run properly (Multizone_AWHP_V2_H&C_08.26_massflow.idf). I am also attaching a file calculating the heat loads for a specific case (Multizone_AWHP_HeatLoads.idf), and the building itself (AWHP_V2_H&C_08.26.b18)

Hope you have solutions!
Thank you in advance,

Laszlo GERGELY
PhD student
Budapest University of Technology and Economics

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