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

[David BRADLEY]

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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> TRNSYS-users at lists.onebuilding.org
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-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
3 North Pinckney Street - suite 202
Madison, WI  53703 USA

P:+1.608.274.2577
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com

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