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Hourly Economizer Status

asked 2016-06-09 09:53:13 -0500

kbk78's avatar

Is there a way to find if the economizer is active during the hour in the hourly report. The output variable "Air System Outdoor Air Economizer Status" only indicated if there is a potential for economizer usage, not necessarily if it is active. Not sure if checking the outdoor air ratio is good idea esp for a VAV system as the economizer could operate part hours too.

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answered 2016-06-09 15:50:54 -0500

I was working on this very problem recently, I wanted to not only see if the economizer was working but I also wanted to make sure that it was bypassing the Heat Exchanger when I wanted it to. What I ended up doing was taking the system node flow rates and temperatures for all the OutdoorAirMixerNodes (inlet, outlet, return and exhaust) and used excel to calculate what was happening.

I knew the following information: Outdoor air flow rate Maximum flow rate through the system economizer limits

From this you can ask excel, if the outdoor air temperature is higher and/or lower than my economizer limit return a 0, otherwise return a 1. Then you can ask excel, if my outdoor air flow rate higher than the amount set in my outdoor air controller, return 1 if yes, 0 if no. Then you can compare, if you have a 1 and a 1 in each column then the economizer is working. That should give you a good understanding of whether the economizer is working. You can also plot this on a graph for all the hourly values to give your a visual interpretation of the entire years worth of data.

You can also view these variables in the ESO viewer, if you look up the outdoor air supply flow rate variable, you can spot the times visually that the flow rate is above the outdoor air flow rate that is expected.

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Asked: 2016-06-09 09:53:13 -0500

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Last updated: Jun 09 '16