[TRNSYS-users] Experience with cooling if there´s an off period??

[David BRADLEY]

Michael,
   There are a few likely causes. First, make sure that you have changed 
the default zone thermal capacitance. In TRNBuild, the default zone 
capacitance is set to 1.2*1.007*ZoneVolume, which accounts only for the 
thermal capacitance of air in the zone. A value 5 times higher than the 
default is usually appropriate. Second, make sure that your infiltration 
and ventilation are set up properly. In normal commercial building 
operation, the outdoor air dampers are turned OFF during the heating 
(and cooling) system off periods. You also may see this effect if your 
infiltration rate is high.
Kind regards,
  David

On 10/12/2012 08:23, Michael Diekerhof wrote:
> Dear all,
>
> I´ve simulated an two hour heating off-period for my Type 56 (year of 
> construction 2002). To keep it easy, i was just working with 1 Zone 
> and a total volume around 500m3.
>
> My problem is that the roomtemperature decrease during the off-period 
> is extremly high. For example: It decreases from 20°C to 17°C (of 
> course depending on Tambient) in the space of one or two hours. I 
> think this decrease is much to high. In this case TRNSYS is not 
> simulating the thermic inertia right ?!
>
> Does anyone have already experiences with this problem and knows if my 
> decrease is correct or seriously wrong ?! In my case i think it´s 
> wrong because of both the huge volume (without internal walls etc) and 
> the missing thermic inertia.
>
> Best,
>
> Michael
>
>
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> TRNSYS-users at cae.wisc.edu
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-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA

P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com

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

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