Vav filters

[techreptdh]

Anybody have thoughts on changing filters in fan powered vav boxes? If this has been discussed before post the thread please.

[techreptdh]

Let me add these boxes have electric reheat, and of course they are filtered through the AHU.

[Chris_Worthington]

Yes they need to be changed :D

I assume that your wondering about the interval as to change them?

Could be 4 X year to 1 X a year. Depends on the building being served :cheers:

[ControlsInMT]

Rule of thumb...if it has a filter, said filter will need changed.

[Control Man]

Just did a building retrofit aprox 9 years old 140 VAV boxes and operator asked WHERE DID the dirty FILTERS come from.

They had never been changed , originals from construction.

[Tech Rob]

Just did a building retrofit aprox 9 years old 140 VAV boxes and operator asked WHERE DID the dirty FILTERS come from.

They had never been changed , originals from construction.

That happens a lot here. I have found huge return air ducts that are like 6' x 3' above ceilings with 15 year old blue filter media still clipped onto the open end.

[Tool-Slinger]

I have a very strong opinion on this based on personal experience in the DFW area. It is normally not done, as there is not much money in it for the contractor and it is a discretionary expense for the tenant or owner. The filters are just discarded and never given another thought.

I have 2 buildings where I do the FPB filters once a year in one and twice a year in the other. They are next-door and I have no idea why I have to do one twice a year but they clog up faster. In both cases the filters are really bad when I do replace them, I use pleated filters.

The dirt will either end up in the filter, or it will be on the desk and furniture and collect on the blower-wheel in time. Ultimately, the dirt is the property of the customer and it should be up to the customer to decide what they want to do with their dirt. I would say it depends on the building. If you have a nice office space or computer rooms then cleanliness is very important and the filters need to be on a schedule. If it is a box retail store, toss filters in nearest dumpster and do not replace.

Beware quoting prices, changing these filters can be a real PITA for a number of reasons.

[ceg22]

in our facility vav filters are changed once a year.

[Control Man]

In the case of the building I mentioned the operations staff do their own filters , all the AHU's are spotless , it is just that no one realized that the VAV's had filters. Other 2 buildings they operate do not have them so they never checked these.

Sad thing is that the owner hired 2 companies over past 9 years to put together a full report on the HVAC / CONTROLS in the buildings and they both missed the filters as well.

[techreptdh]

I appreciate the comments.I brought the question up because we recently had a visit by a team of experts hired by the real estate co. that owns our facilty. Their goal was to find and recommend ways to the maint. staff for improving bldg systems performance. Well, one guy asked another what his thoughts were on frequency of changeing vav filters. To my surprise (and delight, because we have @ 600 vav boxes) he sad " I just pitch em after construction and not worry about em anymore". But I thought I would post the question to get answers from my peers. Btw, I think I'm going to go once a year for the majority and three times a year on all the ground floor units because these are the ones that seem worse.But believe me, the thought of pitch'n em was tempting.

[acdave17]

Glad to hear your not taking the easy road ad pitching the VAV filters.

Always leave it better than you found it

[maxster]

most of the time they are on the perimeters just outside of the walled offices but dragging a ladder around popping ceiling tiles hanging off a 6' ladder over a cubical..those color round dots are great on the ceiling grids to locate on overtime after the troops leave....usually generated when the cold complains come in during the winter nights along those perimeter offices with the unit clocked out in unoccupied

[Tool-Slinger]

most of the time they are on the perimeters just outside of the walled offices but dragging a ladder around popping ceiling tiles hanging off a 6' ladder over a cubical..those color round dots are great on the ceiling grids to locate on overtime after the troops leave....usually generated when the cold complains come in during the winter nights along those perimeter offices with the unit clocked out in unoccupied
Agreed. I use a map, noted which tile to pull and indicated which way to orient the ladder. Also which ladder to use, one building I use 3 different ladder for the job.

[MUNC]

You wouldn't believe how many fan powered vav boxes with electric reheat I've had to replace high limits on from over tripping, had to replace burnt wires and terminals and blower motors. all due to filters not being serviced. Motors packed with dirt, squirrel cages packed, air proving switches "stuck". As far as replacing or tossing filters??? pay me now or pay me later!