Re: [TRNSYS-users] Control of on active layer

["Jeff Thornton" <thornton@tess-inc.com>]

<I would like to pre-heat the inflow of the ventilation during the
heating period to see the impact that this would have on the heating
bill.

To do so I would like find a controller to model:
if Tzone>20°C then Tinflow=Toutside_amb
if Tzozne<20°C then Tinflow=35°C

Do you know wich controller should I use?>

<All you need is an equation:

Tinflow = gt(Tzone,20) * Toutside_amb + not(gt(Tzone,20)) * 35

the GT and LT functions return either 0 or 1, so this contruction gives
you, in effect, an in-else statement.>

While that seems like the ideal solution, using a simple equation to watch
the zone temperature and control the heating temperature will likely
result in a non-convergence situation.  During one timesteps, the zone
will likely rise above 20 C when the heating temperature is 35 and fall
below 20 C when the heating temperature is ambient - causing an unstable
solution.  I would suggest you use either the thermostat model or the Type
2 controller - they're made to handle situations like this.

Jeff



Jeff Thornton
President - TESS, LLC

22 North Carroll Street - Suite 370
Madison WI 53703 USA

Phone: 608-274-2577
Fax: 608-278-1475
E-mail: thornton@tess-inc.com
Web: www.tess-inc.com