VAV box flow station not reading any more
VAV box flow station not reading any more
(OP)
We have an office building where many of the VAV box flow stations don't read the flow anymore (just read 0). I also measured the dP manually and didn't really get much of a reading. My suspicion is that over the years the pitot-tubes in the flow rings got dirty.
this seems to be the only building where we observe this problem and the affected VAV boxes basically act as CV.
None of the contractors I talked to ever heard of such a problem. The VAV boxes are not very accessible, so we can't easily cut open the duct to clean the flow station. I believe they have the flow ring like shown here.
Did you ever have such problem and how did it get resolved? the AHU has MERV 13 filter, so there should be little dirt. I wasn't here for construction, so it is possible there was construction dirt.
this seems to be the only building where we observe this problem and the affected VAV boxes basically act as CV.
None of the contractors I talked to ever heard of such a problem. The VAV boxes are not very accessible, so we can't easily cut open the duct to clean the flow station. I believe they have the flow ring like shown here.
Did you ever have such problem and how did it get resolved? the AHU has MERV 13 filter, so there should be little dirt. I wasn't here for construction, so it is possible there was construction dirt.





RE: VAV box flow station not reading any more
The building is 30 years old and has about 500 boxes-never seen dirt loading hit more than a few at a time, and never across every box controlled by the same NCM or NAE. In this case, we get a question mark instead of a zero. Are the failures common to a single NCM/NAE?
RE: VAV box flow station not reading any more
RE: VAV box flow station not reading any more
B.E
You are judged not by what you know, but by what you can do.
RE: VAV box flow station not reading any more
RE: VAV box flow station not reading any more
RE: VAV box flow station not reading any more
the problem is as it is we can't physically access the flow-ring to see if it is dirty.
RE: VAV box flow station not reading any more
B.E.
You are judged not by what you know, but by what you can do.
RE: VAV box flow station not reading any more
RE: VAV box flow station not reading any more
Are you getting any measurement at all, on the air tubes, can you get air to flow through the pitot and the static lines?
Can you get a Manometer connected to the airlines? I am presuming that the existing DP sensor has a static, or does it just use a general duct static from somewhere else in the system.
B.E.
You are judged not by what you know, but by what you can do.
RE: VAV box flow station not reading any more
RE: VAV box flow station not reading any more
RE: VAV box flow station not reading any more
this may be a good opportunity to provide access panels to help for future maintenance not only for HVAC.
RE: VAV box flow station not reading any more
RE: VAV box flow station not reading any more
RE: VAV box flow station not reading any more
RE: VAV box flow station not reading any more