Tracer VAS Setup Problem

[Ice Machines]

I have an IntelliPak RTU with cooling only, coupled with VariTrane VAVs (Comm3/Comm4), that are defined in Tracer Summit as a VAS. The system behaves properly in all respects but one.

When in Unoccupied mode (controlled by schedule), after a few hours with RTU and all VAVs in "unoccupied" mode:
1. The VAV units go into Night Heat/Cool mode to heat (all 8 of them, within a 1 hr. period, once it'sw cold enough)
2. The VAV units open their air valves & heating coils to heat
3. The VAS's AHU Fan Request = 'ON'
4. The RTU's Present Value = Night Heat/Cool
5. The RTU's Active Mode = Unoccupied Cooling (the RTU is cooling only)
6. RTU Fan will not run.

Not sure what I've missed, but any help would be grreatly appreciated.

[Chris_Worthington]

Thread relocated to "Controls"

[controldude]

Try a simple CPL program that will tell the RTU to go to Opt Start this will control the fan on keep OA Damper closed. ie:
PROGRAM NIGHT_HEAT_COOL

DEFINT Night_Heat_Cool

DEFOBJ RTU, VAS

/// This program controls the Present Value of an I-PAK to OPT/START

/// If the Present Value of the vas is night heat cool

///Routine Execution: This program is executed every minute.

///Routine Text File:night_heat_cool.CPL

RTU = {Retreat Bldg RTU}
VAS = {Retreat VAS}
IF (VAS.{Present Value} = 8)
THEN
CONTROL ({Retreat Bldg RTU}, {Present Value}, 1, 5, SET)
ELSE
CONTROL ({Retreat Bldg RTU}, {Present Value}, 1, 5, RELEASE)
END IF

END

[Ice Machines]

Many thanks!!!! I will try when the site re-opens after Xmas. I have to ask, though, why does the Summit application not do this on its own? Seems to me to be a fairly basic feature that most HVAC applications would want. I mean, why does the VAS application activate the AHU Fan Request = 'ON' if it's not going to actually activate the fan?

[mallron]

Your description of what's going on makes me wonder what's controlling the RTU to "Night Heat/Cool", I've never seen VAS control to 'night heat.cool' so I wonder if Area is taking control of the RTU and it's not responding because it's 'cooling only'.