[TRNSYS-users] Error Message 441 after using equation

[David BRADLEY]

Ole,
   I'm not sure if anyone responded to you about this but it is a 
classic problem in controls. It is not just a TRNSYS problem. When your 
zone temperature is greater than 24 then the cooling turns on and brings 
the zone temperature back to 24C at which point your controller realizes 
that cooling should be off because the zone temperature is not greater 
than 24. Cooling is turned off and the zone temperature rises above 24C 
again. You need to use a controller that has a deadband (cool to 23.5C 
and then turn off. Don't start cooling until zone temperature reaches 
24.5C - or something like that.

   What makes this a little complicated in TRNSYS is that you're mixing 
two ways of doing heating and cooling (energy rate control and 
temperature level control). I would recommend that you go though the 
tutorial called "Temperature Level Control from Energy Rate Control" 
that can be downloaded from 
http://sel.me.wisc.edu/trnsys/downloads/tutorials_and_examples/tutex17.htm)
Best,
  David





On 1/30/2015 03:36, Ole Nienaber wrote:
> Dear All,
>
> I'm modelling a building zone with TRNBuild and I'm controlling my 
> heat and cooling demand by the Heat and Cooling Type Manager. It 
> worked when I use a simple schedule for my Cooling Type Manager to 
> control the temperature. But then I tried to use an input instead of 
> the schedule. In the deck, I implemented an equation which should give 
> back 1 or 0 while using the mathematical function GT(T_zone, 24), so 
> that I get back a 1, when my Zonetemperature increases over 24°C and 0 
> otherwise to regulate my cooling. But when I tried to calculate it, I 
> received this message like 30 times
>
> TRNSYS Message 441 : The inputs to the listed units have not converged 
> at this timestep. The values at the last iteration will be used and 
> the simulation will proceed.  Reported information  : UNITS: 56
>
> and then this one:
>
> TRNSYS Message 450 : The maximum number of warnings allowed per 
> simulation has been exceeded. Please fix these warnings or increase 
> the limit on the number of warnings allowed per simulation (LIMITS 
> command)  Reported information  : Not available
>
> Can anyone help me with this problem?
>
> Thank you so much in advance,
>
> Greetings,
> Ole Nienaber
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> TRNSYS-users at lists.onebuilding.org
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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
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