How to override schedules using EMS?

asked 2019-06-17 20:54:18 -0600

I want to implement a specific control strategy to control the ventilation system coupled to a radiant cooling system. The ventilation system should be on during the occupation period (from 8:00 to 17:00). I also want to turn on the ventilation system during at night (after 17) or early in the morning (before 8) but only if the inside surface temperature is 1 C above the dew point temperature and only for 1 hour or 2 hours after it turns on. I have tried to use schedules as sensors and as actuators to accomplish this, but I am having difficulties with specifying the operation duration. Does anyone have any suggestions? Thanks in advance for your help.

answered 2019-06-21 12:03:36 -0600

shorowit

11931 ●203 ●9 https://www.nrel.gov/b...

Here's an example of using EMS to override schedule values for purposes of night ventilation: https://unmethours.com/question/8954/...

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@shorowit thanks for your answer. I checked that link before and it helped me to modify the schedules as I wanted, but as I previously mentioned, I am still having difficulties specifying the operation duration. I am still trying to figure out how to turn on the ventilation system when the dewpoint temperature is at 1 degree below the surface temperature, but only for a prescribed amount of time. I know I should be able to model this starting and stopping in EMS by using Trend variables to record the history of the actions, but I am still struggling with it.

andresgallardo ( 2019-06-24 10:09:15 -0600 )edit

I wouldn't think you need to use Trend Variables. Rather, you could use some of the built-in EMS variables to record the hour/day/etc when the ventilation system turns on, and then compare the current time to that start time to determine if it should turn off.