#1970 SZVAV Heating Controls not functional

[Nikhil Kapur]

CEC : for a SZVAV it doesn’t seem intuitive, why does the min CFM of the fan affect what is needed for heating? Why wouldn’t the fan ramp up (as needed) as the heating demand increases, as a VAV system should?

[Nikhil Kapur]

DR - This is a known issue; see Issue #1424

This short-coming was also known back when I first implemented SZVAV. At that time, I tested most of the available E+ controls and I was never able to get the fan to ramp up during heating. I can try to find an email, but I'm pretty sure I informed the team of this short-coming when we first implemented SZVAV.

The only reference to SZVAV I can find in the E+ documentation is in the I/O ref for VAV HVAC Template. However, back when I implemented SZVAV, I tried this control with our current AirSys configuration and found that it didn't work (used way more energy than the other Warmest control strategy). All my testing was done quite a while ago, so I could revisit the issue to see if, for some reason, it now works.

Recommend looking at using UnitarySystem, SZVAV was one system I wanted to test with it to see if it fixed this control issue.

[John Arent]

No packaged DX single zone VAV unit that I have seen or tested continuously modulates the airflow in heating. Recommend no change.