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Thread: Outside Air Measurments
01-07-2010, 06:40 PM #1
Outside Air Measurments
I am currently working on a school project and am being told that it is my responsibility to set the required outside air on all air handling equipment. I have been in the HVAC trades for 23 years and have never had this expected of me ( maybe a tenant fit out or auto shop years ago..but never a school ) . I was instructed on how to adjust the economizer damper to the " thickness of my fingers " to achieve " 20 percent " . There is a " certified balancer " awarded to this project ( paid by the customer ).
I tried to explain that I am not certified by any " air balance authority " , ' NIST has never seen any of my tools " , but I'm still being told that it is mine to do. And it is written in the job specifications that it is ours to do ( and what is this " balance company " even there for? ).
I have alerted them to ASHRAE 1999-62 ( an email link ) . I'm sure I'll be sticking a screw driver in these " min pots " ( 2002 I'd refuse ...but things are kinda tight now I guess ) ...but any ideas for sarcasam / retaliation apreciated.
01-07-2010, 08:37 PM #2
Who is asking you to set OA? The school? Your boss? Or are you the boss?
The best way I know to set OA is by temperature but there needs to be 10F or better difference between return and outside to do that. When you do it that way you will see some units with the damper almost shut so it will look like it hasn't been balanced.
Grill airflow has to be in the ballpark to do OA, so first step is to verify indoor supply is within 10%, then set OA, then recheck one of the supplies to verify that hasn't changed much or any.
I would ask who is doing the indoor balancing, that I need that done first.
That being said, I am sometimes thankful to be doing balance because I will actually be measuring flow, not just sitting in my truck making up numbers. They could at least be creative and throw in some 8% low or 9% high values from time to time, instead of making it look like everything is perfect.
01-07-2010, 10:18 PM #3Professional Member
- Join Date
- Mar 2003
if it were me, i would let them know that i will be more than willing to set the damper position while the balancer takes his readings.