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Why does sunspace ventilation cease at night? (eQ 3-64)

asked 2014-10-22 13:55:44 -0500

updated 2015-11-08 10:36:49 -0500

Hello all,

Looking for advice on proper sunspace venting. I have a single zone/space shell which is entirely a sunspace and construction is almost entirely windows. The intended operation is for the space to be heated to 73F via HVAC, float up to 80F from solar gain, at which point the windows open and the space hopefully equalizes with ambient temperatures (maybe a bit higher). The hourly reports show that there is NO natural venting between about 8PM and 5AM, which during the summer causes the space to stay at ~90F at night, leading to 130F space temps the next day even though the windows open properly. I think I can keep the space from overheating if I could just maintain the sunspace venting at night.

HVAC type is Unit Heater Zone venting schedule (SS-VENT-SCH) is set to 1 between 3/31 and 10/31, and 0 otherwise (which successfully prohibits sunspace venting during the winter months) Venting threshold temperature (SS-VENT-T-SCH) is to 80F year-round Zone heating setpoint (HEAT-TEMP-SCH) is 73F year-round Infiltration rate (AIR-CHANGES/HR) is steady at 3 ACH, with natural convection venting constant (SS-VENT-CST) set at 2.5 ACH. If SS-VENT-CST is set any higher I get an error which aborts the run (I think because the dT between the space and OA is too high)

Is there some other parameter/schedule that is causing the sunspace venting to cease at night, even though the above schedules are essentially ON at night?

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answered 2015-05-08 10:47:23 -0500

I know this thread is old, but - Could this be due to the outside air schedule taking a "0" value at night? Its similar to getting an economizer to work at night by setting this value to "0.001" in the schedule, which allows the economizer to turn on. Look at the help file on the OA schedule trigger values and see if this works....if your're still working on this...

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Asked: 2014-10-22 13:55:44 -0500

Seen: 359 times

Last updated: May 08 '15