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-   -   How to bypass industrial unit locally... (http://www.diychatroom.com/f17/how-bypass-industrial-unit-locally-149645/)

theatretch85 07-09-2012 07:27 AM

How to bypass industrial unit locally...
 
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I'm trying to figure out how I can bypass this unit locally and wondering if someone can tell me how. Previously all I had to do was set the switch from "auto" over to "manual" which works on another unit in the same area. This no longer activates when set to "manual" and hitting the "start" button on the keypad doesn't go anything. I am doing some work in the area of the building that this unit serves and just want the a/c on for a little while.

biggles 07-09-2012 03:41 PM

that should be full HZ speed as in Constant Volume.is it just a air handler or a self contained cooling unit....? check out on the other owkring unit in manual what contactor closes in manual...then check for voltage and continuity on the non-working one...

theatretch85 07-09-2012 07:38 PM

I believe it is an air handler unit, its mounted to a wall in a maintenance room. I was thinking there has to be some key combination to get the unit to "Start" with the start button. The working unit has a light lit up on the start button, this one is lit up on the stop button and pushing the start button doesn't do anything. I even tried holding the button for a few seconds and nothing. I'm not exactly interested in stepping on anyone's toes by opening this unit up to start poking around and testing anything. I just was curious if I am missing something to get the unit to "start" manually. When I switch the other unit from auto to manual it starts right away (and this one did a couple weeks ago when I was in there, but not this last weekend).

COLDIRON 07-09-2012 07:39 PM

Equipment looks like it's tied into an energy management system (main computer) that no matter what you index it to the program is controlling it.

theatretch85 07-09-2012 07:44 PM

I know it's tied into a central computer, (and seems to be why its hot and humid in this part of the building) hence the reason for switching it to "manual". Which like I said in my last post it was working by switching it to manual mode a couple weeks ago.

biggles 07-09-2012 09:53 PM

if it worked before in manual and doesn't now the BAS has it out they control AUTO and MANUAL

theatretch85 07-09-2012 10:03 PM

Hmm, I was afraid of that. This doesn't sound like I am going to have any luck in getting this thing to run for me.

I'm guess it wouldn't matter in what order I set these two units to "manual" mode in right?

Unless anyone else has anything to add I guess I am going to have to track down someone at this building to get the a/c on next time I'm there.

Thanks for the replies!

COLDIRON 07-10-2012 05:52 AM

Actually that's the first thing you should have done before turning any switches on such an expensive piece of sophisticated equipment.

biggles 07-10-2012 06:11 AM

when you put those to manual that is direct 3 phase from the source into the panel there with the key pad off line and not reading anything.might also be a fire situation as smoke purging that the other runs manual and that one doesn't.imagine the building engineers seeing you diggin' into the contactors...they would flip out:wink:.take note on the working one which contactor closes in manual if you get to see it.now thinking back the key pad goes dead in manual run.:thumbsup: did you attemp to ramp the VFD up in manually off the key pad reading the Hz.

theatretch85 07-10-2012 10:09 PM

I don't know anything about these other than when putting it in manual it came on. I've tried resetting the power to the unit (big black switch at the top) and it seems to have no effect. The working one shows something different on the display (when in manual mode) and the green start button is lit up.

Not even sure how to do this:

did you attemp to ramp the VFD up in manually off the key pad reading the Hz.

I know hitting the "Display" button cycles through I think 2 display options, that seems to be the only button that does anything on the key pad. When I am there next i'll take a picture of what the working one shows, maybe that will help.

vln 07-10-2012 10:40 PM

Try turning the knob from normal to test. It might override the automated system.

COLDIRON 07-11-2012 05:57 AM

Try leaving it alone and schedule the work with the building super to have the unit indexed to on when you are working in the area.


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