Trane Inteelipak trips on "low supply air temp"

[thecomp]

I have a 25 ton Trane Intellipak, which is under factory warranty, and it is tripping on "low supply air temperature" (Human Interface) only on very cold days and at start-up when the outaide air temperature is 15F or colder.

Here is what I observed, under 10F, and windy conditions:

After resetting the disconnnect off and on, the unit started.
Two minutes later, the steam pipes, going to the intellipak, got warm.
Two minutes again, and the supply and return blowers started.
About 30 seconds later, the compressors came on (no condenser fan, thank god) and ran for about 3 minutes.
I cracked opened the filter access door and observed the fresh air opened 100% and the return was closed.
The compressors stopped.
I left the roof

Trane is blameing our building automation system because they can't find anthing wrong. And they want to install a time clock and sensor to control the unit. The area in question needs more cooling because of its' design and will cycle cooling on 0F days and nights.

Regardless of who is to blame, the fresh air and compressors sound like a problem.

Any ideas?

[The Doctor]

have you sorted through the supply air tempering ? that much said, I'm not sure if the sensor looks at the temp before or after it looks to your supply air tempering parameters... I'm involved in similar issue..and will post if it gets resolved. hope you get it taken care of...:cool:

[maxster]

take the unit out of BAS and run it stand alone,the tripping sensor is doing its job.your driving for 100% OA and that is a exhuast fan in the rear not a return fan at 15F.find out why the compressors are coming on and the CFs are off because it is toooo cold.check/read your OA sensor that the unit runs might be wacked reading a false temp OA.two most important things to check out.....why the unit is doing 100% exhaust/OA and the compressors are trying to run with that ambient?

[chiller32]

I have a 25 ton Trane Intellipak, which is under factory warranty, and it is tripping on "low supply air temperature" (Human Interface) only on very cold days and at start-up when the outaide air temperature is 15F or colder.

Here is what I observed, under 10F, and windy conditions:

After resetting the disconnnect off and on, the unit started.
Two minutes later, the steam pipes, going to the intellipak, got warm.
Two minutes again, and the supply and return blowers started.
About 30 seconds later, the compressors came on (no condenser fan, thank god) and ran for about 3 minutes.
I cracked opened the filter access door and observed the fresh air opened 100% and the return was closed.
The compressors stopped.
I left the roof

Trane is blameing our building automation system because they can't find anthing wrong. And they want to install a time clock and sensor to control the unit. The area in question needs more cooling because of its' design and will cycle cooling on 0F days and nights.

Regardless of who is to blame, the fresh air and compressors sound like a problem.

Any ideas?





First off you need to tell us what type of hvac system you have because that will determined how you setup the rooftop unit. example is this a vav unit or cv unit. if its a vav unit do you have reheat? is moring warnup setup? is the unit configured for supply air tempering? ( this might not be an option with steam heat. I can't remeber ) what is the min OA damper setting? If you need to check the mech cooling lockout setpoint. if its set too low they will run.

To set one of these units up you really need to read the book, and based on your installation make adjustments to the default settings and unit configureation to insure correct operation.

[thecomp]

We found a very poorly located factory outside air sensor, so we relocated it in a better spot in the middle of outside air in take. It was reading high about 15 F, especially on sunny, cold days.

I know many techs wouldn't agree with this, but the HVAC system is a constant velocity and VAV.:(

Keep me posted if anyone comes up with anything.

Thanks!

[duke of earl]

Check the sensor wiring and see if it is bundled along with the fans wiring. If so relocate the sensor under the condenser coil and reroute the wires. This was a problem in the past and was Trane's recommendation for a fix.

[duke of earl]

Please enlighten us on the constant volume/VAV setup.

[thecomp]

I'm not the engineer, only the messenger, but from what I was told and saw from the drawing, most of the office area is VAV and some is constant volume.

[tim fox]

It's not unusual to have a unit serving a combination of zones. Office spaces,restroom/locker rooms,labs,kitchens.

[onebadgrif]

I have come across that problem just recently . . . was on 2 nd or 3rd floor of an office building 2) 80 ton intelis and one 60 i think it is . . . . there is a computer onsite used to monitor . . it controls hw pump as well which starts the whole ball rollin , , we also schedule on and off times and hollidays with it . . it was warm in this suite . . i didnt like the air temp so i went to look at unit . . noticed right away power exhaust was on and almost wide open . . not the other 2 units . . . all are setup to start exhausting if outside air is more than 15% open . . keep the building pressure balanced . my supply air temp was like 62 or 63 . .. i reset unit . . it staged up normally no power exhaust supply temp good. went to onsite computer and it was off rebooted it checked everything out all good it has happened more than once now . . only to find computer is down