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View Full Version : Static Pressure Reset with Distech GFX


381engineer
03-21-2010, 09:26 PM
I am working on a code snippet for static reset and I'm trying to figure out a way to disregard any VAV's that are at 100%. I am currently using the nvi for fan_in_avg configured for Hi_Select bound to the VAV damper position.
It seems to me that the only way to do this would be to bind the VAV's to individual nvi's.
Hopefully I'm just missing something simple.

Thanks,
azzad
03-21-2010, 09:52 PM
Why do you want to disregard the 100%?
381engineer
03-22-2010, 01:34 PM
Why do you want to disregard the 100%?

I'm going to assume it's a bad box and if it's not the others won't be far behind.

I may just set an alarm to let me know when the first box hits 100% during occupied times.
dapper
03-22-2010, 02:55 PM
Generally a rogue box alarms after a period of one hour or so of 100%. I would definitely put in some sort of delay.

I have also been wondering how this would be done in a Distech controller seeing how the NVIs are somewhat limited. I am curious to see if anyone else does this. It's not unusual to see this in an engineers spec.

Have you tried to bring the nviDamperPosition into your iLON and manipulate the data there? It's been some time since I worked with the math functions but pretty sure you can do average and high select etc.
381engineer
03-22-2010, 03:14 PM
Generally a rogue box alarms after a period of one hour or so of 100%. I would definitely put in some sort of delay.

I have also been wondering how this would be done in a Distech controller seeing how the NVIs are somewhat limited. I am curious to see if anyone else does this. It's not unusual to see this in an engineers spec.

Have you tried to bring the nviDamperPosition into your iLON and manipulate the data there? It's been some time since I worked with the math functions but pretty sure you can do average and high select etc.

The math stuff is built into the nvi (nviFP18) so no problem there, just no way to break out a rogue as far as I can tell.
azzad
03-22-2010, 03:57 PM
If it is a bad box don't include it?
381engineer
03-22-2010, 06:49 PM
If it is a bad box don't include it?

Even a good egg goes bad sometimes.
azzad
03-22-2010, 07:13 PM
If your maximum static setpoint is the same as before you applied the reset then you will be no worse off than before you implemented it.

You could catch the good eggs that have gone bad on your regular service.
NINAX
03-22-2010, 07:47 PM
Have you tried to bring the nviDamperPosition into your iLON and manipulate the data there? It's been some time since I worked with the math functions but pretty sure you can do average and high select etc.

I would think along the same lines, except AX.
It would be a really nice 'future upgrade' suggestion for the fan-in nvi.
leaflying
03-22-2010, 08:38 PM
You can handle that in a program object.


I would think along the same lines, except AX.
It would be a really nice 'future upgrade' suggestion for the fan-in nvi.