[TRNSYS-users] Two warnings regarding the 954c air source heat pump and the 166 controller

[David BRADLEY]

Jim,

   I am not sure to what extent you changed the time step but I am 
almost always using something between 1 and 5 minutes these days. If 
your heat pump is the right size for the space and you're using a 1 
minute timestep already then you might send the project to your 
distributor in the hopes that they can give some guidance.


   The heat pump data file out of range issue is not uncommon and if it 
isn't happening too much of the time then I wouldn't worry about it. The 
issue is that the routine that reads that data file can interpolate 
within the range covered by the data file but can't extrapolate beyond 
it. Instead, if a value comes in beyond the range, the routine will just 
find the closest value (at the bottom or top of the range given) and 
report that value. This can get you into some trouble; if your heat pump 
data file only goes down to an outdoor ambient temperature of 5C and yet 
during your simulation an outdoor ambient temperature of -20C is 
encountered then your heat pump will report the same available heating 
capacity at both 5 and -20C, which probably is not accurate. Again if it 
is only happening a few times per simulation it is nothing to worry 
about. If it is happening more then you can edit the data file to extend 
its range.

kind regards,

  David



On 08/18/2021 12:42, dimitris soukoulis via TRNSYS-users wrote:
>
> Hello! I am modeling a multizone building air conditioning scenario 
> using the type 954c air source heat pump. I keep getting two kind of 
> warnings. *The first* is for the type 166 controller and says that the 
> controller is stuck for some considerable amount of time (17 percent). 
> I tried changing the heat pumps characteristics to fit the rooms needs 
> better and also changed the timestep  but  I couldnt erase the 
> warning. *The second warning *was for the heat pumps data file. It 
> says that in the simulation the cooling performance data file was 
> called several times with a first (and sometimes second and third) 
> independent variable value below (or sometimes above) the range 
> supplied in the data file. Does anybody have any ideas about how to 
> fix those two problems ? Thanks in advance.
>
> Jim Soukoulis.
>
>
>
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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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