Jon,

If you can get me a copy of the Test and Balance report and  a link to the IOM manual, I should be able to walk you through changing the fan speed.  Should be well within your capabilities, but i understand if you don't want to potentially make yourself liable for any unit failures.

I can ask the landlady.

On 8/18/2024 at 12:41 PM, BillyBones said:

JHCC, have you any info on who did the installation? There maybe some kind of service agreement with the unit that they will come out and look at it for free.

I had a chat with the landlady today, who says (A) that she won't do any more business with the company that did the installation, but (B) that I am welcome to open it up and make adjustments. 

I'll see how things go with the addition of sound-absorbing material, and if there's further reduction needed, we can explore the option of changing the settings.

The sound absorbing foam panels have arrived and are awaiting installation.

They come vacuum-packed, so you have to let them expand overnight before installation. More to come....

First panels are up. Hard to tell from the decibel meter, but there's already some noticeable improvement (which is to say, people can have a normal conversation nearby even when the AC is running).

We’ll see how things go with the addition of the “floor” to the open space. Looks like the filter could use replacing as well. 

They might be fun to paint if it didn't un-damp the sound.

A clean filter should reduce the work the blower has to do and reduce noise proportionally.

Frosty The Lucky.

 

The plywood I plan to use for the "floor" is already painted the same color as the wall, and the "wood wool" panels I want to use for baffles on the sides will be hiding most of the foam from view.

That's not what I meant John. I was thinking of painting each fin thingy, a contrasting color on opposite sides. That way the overall color(s?) would change when you move. Oooh, it could look REALLY cool if they vibrate or shiver when the AC is running. 

I'm surprised you're using plywood rather than baffle board to box it. Baffle board doesn't look as good as ply or OSB even but it really damps noise. I used it to box the LA Abrasion machine in the mat lab, back when. The LA drum is IIRC about 30" dia x 30"+ hardened steel drum with a lift lug that turns about 45 rpm. You charge the drum with 1,000gm of aggregate and 12, 1 lb. hardened steel bearing balls. When it's running the lug lifts the sample and balls, dropping them so they impact the drum as perpendicular as possible. 

LOUD doesn't cover it, you could hear it running in or out of the lab, lab building and across the state yard. Gluing wool felt to the drum made a huge difference but it needed more so it got a baffle board box that I ended up having to add another layer with fiberglass insulation in the space like a frame wall. 

It was still loud but bearable in the same room if you wore ear plugs. 

Anyway, baffle board works well and a lick of spackle compound troweled over it makes it smooth and paintable to "invisible."

Frosty The Lucky.

32 minutes ago, Frosty said:

I'm surprised you're using plywood rather than baffle board to box it.

Only using plywood for the floor, and its inside/top surface will be covered with the same foam panels as shown on the wall and ceiling.

stupid question, and just point out the obvious I think.  But how recently was the filter changed? The date written on the side looks like 2023?

I may have to call and find out if the sound damping panel I used is even available, I can't find anything remotely like it online. I'll try different terms for a while before calling one of the local speaker cabinet shops. The stuff was a low strength construction board like fiberboard though softer and weaker. 

Heck, the stuff might not be available anymore, just because I built the LA box maybe 35 years ago. Last time I drove past the lab the LA machine was in a separate small building with flashing light on it and a sound wall around it. 

Frosty The Lucky.

Cut out the plywood, bolted it in place, and added its sound absorbing foam, filling in a couple of bits on the wall as well. Also changed the filter.

Result: TOTAL SUCCESS. Significant difference to the ear, and a 10 dB drop on the meter. I may not even bother with the side baffles, except perhaps for cosmetic reasons. 

10 dB drop is a huge improvement.  Might be another career in this for you if you aren't careful....

It’ll have to get in line behind fundraising, blacksmithing, and selling yarn!

Thanks for your advice; it’s very much appreciated.