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 73* via HVAC, float up to 80*F 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 10PM and 5AM, which during the summer causes the space to stay at ~90*F, leading to 130*F space temps the next day even though the windows open. 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 80*F year-round
Zone heating setpoint (HEAT-TEMP-SCH) is 73*F 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), but more on that later.

So my question is: 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?

As for the error, I have seen this brought up before but never any insight given:

***ERROR***********************************************************************
In routine TEMDEV for ZONE E3 Zn (G.1) on 4/10 hr 13 (InitialFlg = 0)
SUNSPACE INTERIOR-WALL calculations produced bad values:
CSSVEC (convection) = -1282312. CSSVEC (conduction) = -177074.
This would cause a -21. degree ZONE temperature change. Values are being ignored.
Check wall definitions for errors and report this inp/lib/wth to DOE-2 support.

Thanks!

William Hillsinger, EIT
Project Manager
Energy Squared, LLC
1 Independence Way, 3rd Floor
Princeton, New Jersey 08540
609-751-9655 ext: 109
609-751-9658 fax
william.hillsinger at energysquaredeng.com
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