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Re: [TRNSYS-users] Simplified heating and cooling based on operativetemperature

Sabine,

  1.    it takes two timesteps for the ideal heating to reach the required setpoint..

Is this normal or what am I doing wrong?

if you have limited the capacity of the heating type in TRNBuild, it could take some time for the building to reach its setpoint. If you have unlimited heating capacity then it should reach the new heating temperature instantly. However, Type65 (the online plot) only plots one point per time step and it draws a line between points; looking at the figures that you attached, I think you are just seeing Type65's interpolation. If you hold down both the SHIFT and CTRL keys at the same time and move your mouse around the plot, you'll see the ACTUAL value of each output (not the interpolated value that Type65 is showing you. You can prove it to yourself as well by changing to a shorter timestep - you'll see that it appears now as though it takes less time to reach setpoint.

2.   When using a schedule in trnbuild (so not in the operative correction trick of above), somehow the heating only switches on at exactly the time of the switch (in my case 7 h and 17 h), while I assumed the schedule to mean that at the new time the new temperature must be obtained (see attached document). The heating switches OFF at exactly the changing time, so it then takes the new setpoint temperature. (see figure 2).

again, I think this is purely a matter of how the online is plotting the results (one point per timestep).

3.   Does anyone know why the temperature seems to be fluctuating a little (in other words: it is not a smooth line) as soon as the heating turns off?

Also when using a smaller timestep the line is not smooth, but the temperatures stay constant during a hour, so the line looks like a staircase..

     (note: the non-smooth line occurs when the heating is OFF)

I think Arie's response is the most probable one here.
Best,
 David



 
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