The architectural firm I work for has been trying to trouble shoot an annoying noise in a newly constructed building since January’s punch list.
The tenant has moved into an office section and has a noise that the contractors, engineers, and architects, so far, cannot correct, or find. All efforts have been futile!
The sound would be similar to a “loud” CPU/hard drive! It appears only on sunny afternoons in two offices on the western wall of the building.
How does one find the source of an intermittent noise?
What special instruments are needed?
Any thoughts from the BT crew???
Thanks…………………………Iron Helix
Replies
If this was a home I'd suspect a thermostatic attic fan. In a commercial building some sort of thermal expansion is probably more likely.
The engineers should be able to find someone with a data recorder that could be hooked up to microphones or accelerometers attached at various places in the structure.
Re:"If this was a home I'd suspect a thermostatic attic fan."That was my first thought. I have see it a few times. It can be a serious issue partly because a fan motor that seizes up can overheat and cause a fire. Most motors larger than a small shielded pole unit have a thermal overload that will cut the power if the motor overheats but these too are mechanical devices and they do wear out. While some fail open, a good thing because they make it essentially fail-safe, too many times I have seen them fail closed. Very bad.On one house the HO complained that on hot days there was an annoying but slight roar that had gotten louder with time. We suspected the bearings were going. It was a complicated roof built in a fairly modern dormer-over-deck layout. Which means that all the roof deck areas were not easily accessible. In a few spots it was clear people had gone at the roof deck under dormers and sections with a saw. Clearly after some of these holes were cut insulation was added. Both disguising the holes and making their use more difficult. Nothing like a roll in the fiberglass while sweated up to make a day go smoothly. We got called in and couldn't find an exterior vent. Even walking around the house at a considerable distance and using binoculars. usually an easy to spot allocator for through-roof fans. You might want to give this a shot. We could hear the sound but couldn't tell where it was coming from. And really weren't sure it was an attic fan. We pretty much figured it was electrical when we cut power to the building and it stopped. Progress. At least we now knew it wasn't ghosts or supernatural. Neither of which are thought to be dependent on electrical power. So then we flipped breakers until we knew which branch circuit it was on. We were hoping they had tapped off an existing circuit. Electricians are lazy, like everyone else. If we tap of a circuit it is likely pretty close to the fan.
Slight breeze getting under siding and vibrating the tyvek. I had one that was a low droan once and one that was an absolute screamer!
No tyvek...30# felt under steel sdg, lucabond & masonry.
...........Iron Helix
only on sunny afternoons in two offices on the western wall
Dan's comment on thermal expansion differential is likely correct. Steel to glass is a big thermal coeff. or expansion (TCE) difference, look for that type interface as a start.
One approach is to do a specturm analysis of the noise and that will tell you the resonant and harmonic frequencies of the source, then one can look for that size/mass panel, etc. .
Some of the acoustics guys I occasionally work with have a whole catalog of spectrum analysis charts for various noise signatures. Steel, aluminum, conduit, etc == all have their distinctive signature.
Junkhound, you just stepped beyond my life's experiences and into the Twilight Zone for me!
But, I will print your reply and take it to the office to the powers that be....thanks!
Surely the university has some of that type of equipment in the science labs.
.........Iron Helix
The general thought is that the afternoon sun heats up the side of the building, thus changing/distorting some "shapes" in the vicinity of the HVAC return air duct intake from the above ceiling space as the return air plenum.
The person in the one office dampens the noise as it vibrates the Ceiling grid system by propping a long (6') skinny wooden stick between the credenza and the ceiling. One can actually watch the stick oscilate! At the same time it seems the sound is coming from the exterior wall and if you reach out and touch the wall the sound goes away for a while!
If you lean your head against the wall or use a dowel between the wall and your ear, nothing is to be heard/felt. It seems the wall is resonating to an unknown source.
The HVAC techs have changed cfm's in the VAV boxes and the static pressure cut-ins at the exterior air handler/coolers....all to no avail! The sheet metal crew confirms that the ducts are insulated, isolated and hung according to good practices/methods. None of the ductwork exhibits vibration. Return air turbulance is still being discussed.
The possibilty of vibration conduction from the concrete HVAC pad supporting the two large air handlers has been discussed as details show that the slab is doweled to the foundation wall of the building. Instruments of detection are needed.
Thanks for all of your replies................Iron Helix
PS...I assume that a CRX is a vibrational wave generator...some kind of laboratory instrument......Right?!!? :>)
Note that the heat may originate in one place and cause expansion in another. That expansion may result in vibration in yet a third place, which may be transmitted until it finds a "sounding board" in a fourth place.
If Tyranny and Oppression come to this land, it will be in the guise of fighting a foreign enemy. --James Madison
10$ stethascope...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
Forget the primal scream, just ROAR!!!
I think ones used my mechanics to find noises (like valve lash) might work well.Rebuilding my home in Cypress, CA
Also a CRX fanatic!
with a CRX .. how can ya seperate all the racket...
medical supply house... Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
I don't know how many post I have read of his but untill you said that I thought he was a crc fanatic
You know the wd40 alternitave.Do you look to the government for an entitlement, or to GOD for empowerment. BDW
go with Tri-Flow instead....
it'll even help a CRX...
did you have a..... duh.... moment....Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!<!----><!---->
Forget the primal scream, just ROAR!!!
OH just a little one.Do you look to the government for an entitlement, or to GOD for empowerment. BDW
Nice one guys! You would hear me laughing too, if it wasn't for the parts falling off your crappy american trucks drowning out the sound :)Rebuilding my home in Cypress, CA
Also a CRX fanatic!
As of yesterday the university (owner) has decided to tentively accept the building with this "weird noise" undiagnosed and "as is" until the 9th month post substantial review.
I would think the "as is" condition would be final when the 12 month warranty expires on 1/3/07.
The expense of bringing in an acoustics engineering firm to assess the situation may outweigh the size of the noise. It has been suggested that the one most effected office be converted to a different use (storage) and the current occupant moved to a different office area.
Once again, I appreciate this forums experiences and insights!
Thank you...........Iron Helix
Use a mechanics stethoscope - here is the link to one.
http://www.amazon.com/gp/product/B0002KPYYU/102-9643695-0909743?v=glance&n=15684181
You can drill a small hole if needed to home in on it.