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Thermostat Tolerance in AvailabilityManager:NightCycle

I don't understand the thermostat tolerance :

The zone temperature must exceed the cooling set point or fall below the heating set point by 1/2 the Thermostat Tolerance in order for the availability manager to signal that the system should turn on.

I want the heating to turn on at night if the temperature falls below 14 °C. I have my heating set point to 16 °C, my tolerance thermostat to 4 °C and my cycling run time to 1600s. So I expected my system to turn on at 16-4*1/2 = 14 °C and to stay on during 1600s. However it is not the behavior I observed: T.PNG

I have only two zones controlled with this NightCycle: image description

Any thoughts on what happens ?

Urado's avatar
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Urado
asked 2016-05-26 03:28:17 -0500
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Once the zone/s temperature falls below 14 C, night cycle turns on the fan which remains on for 1600 s (26.67 minutes). After 1600 s, fan is off for entire zone time step(15 min if Timestep input is 4 and 10 min if Timestep input is 6 etc.). After that night cycle again turns on the fan which remains on for 1600 s and the cycle continues. This is the behavior above plot is showing. Reporting times series data at detailed or timestep frequency will make it easier to see what is happening.

Chandan Sharma's avatar
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Chandan Sharma
answered 2016-05-26 08:49:26 -0500
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The behavior you described is what I expect but not what I observe. The plot I showed already uses timestep frequency (10 min) so why my system turns on above 14 °C ?. Here it's more like 14.8°C and it's not even regular.

I would have understood if it turned on a little below 14 °C (due to the 10 min timestep)...

Urado's avatar Urado (2016-05-26 09:23:01 -0500) edit
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Is output variable Availability Manager Night Cycle Control Status at detailed frequency showing expected control status? If not can you attach spreadsheet with zone temperatures, and above output variable reported at detailed frequency.

Chandan Sharma's avatar Chandan Sharma (2016-05-26 09:44:11 -0500) edit
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Thanks a lot, Timestep (used for the plot) was not enough to see the temperature fall below 14°C ! With Detailed I can observe it:

  • 02/12 04:10:00 14.0875908
  • 02/12 04:12:30 13.82292834
  • 02/12 04:15:00 13.81977706
  • 02/12 04:17:30 14.32698974
  • 02/12 04:20:00 14.98434769
Urado's avatar Urado (2016-05-26 10:32:27 -0500) edit
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