Home A/C compressor noise

[Mschulze]

If I wrap the cylindrical compressor with noise abating insulation, will it overheat or stress the cooling efficiency.? Re.: RUDD central air, outside unit.

[D-Allen]

Has the system been checked lately?

[skippedover]

How load is the noise? If it's an objectionable noise, I'd say it needs some attention. If it's just a normal noise, I don't think you'll do any harm to wrap your compressor anymore than the manufacturers who wrap them in the higher SEER models. The compressor motor is actually cooled by the low side of the system returning cool refrigerant to the crankcase before it's compressed and heated.

[Mschulze]

Has the system been checked lately?
D-Allen: not checked since installed about 4 yrs ago, but the whining noise was there from the start. The installer suggested I do what I wrote, insulate the compressor. I did that yesterday, with a noticeable decrease in noise, but concern over the overheating.

[Mschulze]

As mentioned to D-Allen, it has always been there, and is very objectionable. The is another unit near my house that sounds almost the same, so I have resisted trying to resolve my issue until now, but I did have a Carrier before,and buy comparison it was almost silent.

[lynn comstock]

How load is the noise? If it's an objectionable noise, I'd say it needs some attention. If it's just a normal noise, I don't think you'll do any harm to wrap your compressor anymore than the manufacturers who wrap them in the higher SEER models. The compressor motor is actually cooled by the low side of the system returning cool refrigerant to the crankcase before it's compressed and heated.Right on.

[D-Allen]

The only problem I have ever seen with a compressor blanket was on a Copland compressor where the A/C was installed on a metal roof in direct sun. When the O.D. temp reached in the 90's for awhile. I removed the blanket an cooled it down with water to bring it out of internal overload, checked the charge and never had another issue.

[Mschulze]

Thanks all for replys. In a test yesterday I used un-faced fiberglass insulation to wrap the compressor. A neighbor suggested it would be a fire hazard, that double faced would be better. Comments??

[ScorpionLeather]

Take some ideas from the manufacturers.. My Lennox XC21 has a super quiet compressor. What they did is to enclose the compressor with a metal enclosure, and the inside of the metal enclosure is lined with acoustic fiberglass. A metal enclosure is not the best for noise control on its own (unless it is thick and massive) so I figure that the metal enclosure helps contain any fire.

[lynn comstock]

Thanks all for replys. In a test yesterday I used un-faced fiberglass insulation to wrap the compressor. A neighbor suggested it would be a fire hazard, that double faced would be better. Comments??Unfaced fiberglass is not combustable. Facing is paper and is combustable. If either should get oily, the oil is combustable.

[euroboy]

I did some experiment with my outside unit, and found that how level the unit is makes a huge difference - in my case I used thick rubber to place it between the unit and the bracket - combination of rubber and isolation and leveling made a huge difference.

One thing I am not happy with my new house, is the unit being mounted to a wall using L brackets - I would much prefer the unit being isolated from the house, using it's own pad - that is what I had in my old house and never had any issue with sound entering the house - what is the main reason to mount the AC to a wall as suppose to have a pad isolated from the house ?

[ScorpionLeather]

what is the main reason to mount the AC to a wall as suppose to have a pad isolated from the house ?

Contractor laziness. Something that I'm getting annoyed with my own contractor right now.. even though he's a very knowledgeable guy, he hires young guys who just love to cut corners. Anyone with HVAC experience should know that if you mount a compressor to a wall it's going to transmit the vibrations right into the wall. Probably cheaper than making a pad.

[horrocks]

Thanks all for replys. In a test yesterday I used un-faced fiberglass insulation to wrap the compressor. A neighbor suggested it would be a fire hazard, that double faced would be better. Comments??

Does your unit offer an optional sound blanket? The problem with using fiberglas insulation is that you do not want to get it wet. I have a Lennox unit and installed the optional sound blanket. It helped a little but did not help much with my start up noise that I was trying to muffle. My unit is right outside my bedroom window. I considered a lot of options such as a sound fence, and even moving the unit to the side of the house. My unit was waking me up at night when it started up. I run a white noise fan at night and last night decided to kick it up a notch, and it seems to work. I did not hear the compressor start up at all last night. If this works permanently, it will not cost me a dime for this solution.

[kb3ca]

Walmart sells some of those real soft foam ear plugs that work pretty well also.
lol.

[ScorpionLeather]

I considered a lot of options such as a sound fence, and even moving the unit to the side of the house. My unit was waking me up at night when it started up.

Depending how far you want to take it.. you could even soundproof the bedroom wall. Here's how:

Open up the wall on one side. Cut some of the thicker HardiBacker cement board to fit exactly between the wall studs. Glue it in place using thick globs of silicone. Fix up the side of the wall that you broke open.

To get rid of noise, the trick is to use mass + isolation. The cement board is like a super heavy drywall that adds mass, and the silicone provides isolation so that the walls boards are not coupled together.

And if you have windows, those can also be replaced to reduce noise transmission..