Compressor Blanket

[jasruby79]

Thanks for all the help so far... I can't promise this will be my last question, but I am sure we are getting there. :)

I have been reading other posts about reducing noise on the outdoor unit... Can a compressor blanket be added to a unit that does not already have one? Does this really reduce noise, and by how much? Also..I does it have any ill effects on the compressor? Is this something my hvac company will sell or is this something that a homeowner obtains?

[tpa-fl]

It can be added... but it's not a cure-all. Only 1dB reduction in most cases. They're best at reducing higher-frequency noises, less effective at mid & lower frequencies. They're usually not available for sale to homeowners. If it's RIGHT outside your bedroom window, then I'd go for it...otherwise forget it.

[jasruby79]

any other accessories that can quiet the outdoor unit?
ICP Model # N4A430
Copeland Compressor?

http://hvac-talk.com/vbb/showthread.php?t=136721&highlight=compressor+blanket

[jasruby79]

Here's the reason I am asking about these blankets. I have a new install halfway finished. (HVAC contractor worked late last night, but was unable to finish). Outdoor unit sits about 15ft from property line. City ordinance will only allow 45dB at the property line at night and 55dB during the day.

The unit the contractor is about to intsall is an ICP N4A4 model. Very basic, basic unit and it runs at about 76dB. :eek: I assume this is measured at the unit. I also know from reading posts that the noise will lessen the further you get. The only thing is...how will I know until the unit is up and running?

My contractor has offered to provide me with a free sound jacket from ICP for the unit...but he cannot tell me how much the sound levels will decrease. The other option is to upgrade my unit to the T4A4 model at additional cost. HOWEVER...when the T4A4 model runs in high-speed fan it is rated at 74dB. SO...1.) how loud is 76dB from 15ft away 2.) how much reduction will I see with the ICP "sound jacket"? 3.) Is it worth the extra $$$ to upgrade and see only a 2dB reduction.

Unfortunately, the indoor coil is already in so I don't want to stray from ICP brands. Also, contractor is very reliable and did a very good install on another house for me but not very knowledgable in regards to sound levels, etc.
Thanks.

[lra]

I would go with the blanket. It's free and you won't be that much behind the game (should it be insufficient.) I have personally had much better results than 1 db when using the blankets on Tempstar products-particularly scroll compressors.

[jasruby79]

Do you know if this unit has scroll? Here are the specs. It only claims to have "Copeland Compressor" but I do not see the word scroll.
Since I am not an HVAC person I do not know, does Copeland only make scroll?


http://icpindexing.mqgroup.com/documents/086477/42121520001.pdf

[tpa-fl]

Here's the reason I am asking about these blankets. I have a new install halfway finished. (HVAC contractor worked late last night, but was unable to finish). Outdoor unit sits about 15ft from property line. City ordinance will only allow 45dB at the property line at night and 55dB during the day.

The unit the contractor is about to intsall is an ICP N4A4 model. Very basic, basic unit and it runs at about 76dB. :eek: I assume this is measured at the unit. I also know from reading posts that the noise will lessen the further you get. The only thing is...how will I know until the unit is up and running?

My contractor has offered to provide me with a free sound jacket from ICP for the unit...but he cannot tell me how much the sound levels will decrease. The other option is to upgrade my unit to the T4A4 model at additional cost. HOWEVER...when the T4A4 model runs in high-speed fan it is rated at 74dB. SO...1.) how loud is 76dB from 15ft away 2.) how much reduction will I see with the ICP "sound jacket"? 3.) Is it worth the extra $$$ to upgrade and see only a 2dB reduction.

Unfortunately, the indoor coil is already in so I don't want to stray from ICP brands. Also, contractor is very reliable and did a very good install on another house for me but not very knowledgable in regards to sound levels, etc.
Thanks.

Usually (at least with professional audio and industrial product testing) sound pressure levels are measured at 1 meter (3 feet) away. Assuming they've used this standard way of measurement, 76dB @ 3 ft = 62dB @ 15 ft. Going from 3 feet to 15 feet only reduces sound by 14 dB, on average... Keep in mind that reflected sound can also increase the overall level of sound, ie: sound bouncing off the wall, etc.

For reference, normal speech @ 1 meter is 60dB.
Keep in mind that the decibel scale is logarithmic, thus a 3dB increase in noise is actually double the noise level. I'm not familiar with the ICP product line, but compressor jackets are usually only good for a 1-2dB reduction in noise, which isn't a whole heck of a lot numerically, but does have some effect, just not huge. The best you can do with ICP would be to get the quieter unit AND compressor blanket. 74-2=72, 72-14=58dB...which is still over the codes even during the daytime, but unless you're willing to go with a non-ICP product, that's about the best you can do. Or, just take the 76dB beast and throw the blanket on there, which will give you 60dB at the property line. Not sure which part of the country you live in, but some nice broad-leaf or dense shrubbery planted between the property line and the unit can easily knock the sound down by 5dB or more. Just make sure it give the unit at least 12" to breathe.

The other aspect of this is the actual sound of the unit itself. 2 AC condensing units may have the exact same decibel reading but may sound totally different because they're louder & quieter at different frequencies. This does make a huge difference. If the unit's primarily putting out a very low hum/rumble sound, people usually will find this less objectionable/noticable than a mid to higher-pitched sound of the same level. The tonal quality/balance of the sound is where you're likely to get people complaining about things. I know there's an 8dB difference between my new Carrier HP and my neighbor's new Goodman HP. I can clearly hear their HP over my HP when I'm standing next to my HP...and they're on the next street over. It's the middle frequencies that stand out most on their unit.

How close is the nearest neighbor and does the city code specify what noise sources are covered under the noise laws? Usually AC condensing units are exempt unless they're majorly noisy. In just about every tract home development, 45dB at night / 55dB during the day would be totally unattainable using traditional American-made HVAC equipment. The only thing that's really in that range are the Japanese mini-split systems, which are very quiet and some of them are only 45dB at three feet.

[OOC]

Ignroe this post - read the other. I can;t figure out how to delete- sorry new poster.

[OOC]

I think this is right- feel free to comment. I'm not sure where the sound is measured in the dB ratings, but everytime you double the distance where the dB is measured from the source, sound drops off approximately 6 dB (ignoring reverb, reflections, absorption, blocking, etc.). So, if the 76 dB is measured at 1 ft, at 16 ft, the sound would be approximately 52 dB. Here is a website showing this with a calculator-

http://hyperphysics.phy-astr.gsu.edu/hbase/acoustic/isprob.html#c3

I would think though, that adding a hedge between the unit and property boundary may help- just not too close to the unit to cause air flow problems. Who knows, with landscaping, soil, trees, etc. there may be ebnough sound absorption to get you to the 45 dB easily.

[Mr Bill]

I had a customer once that took a small kitchen trash bag wrapped it over his compressor
and tied it down around the bottom of the compressor, then opened up a hole in the bottom
of the trash bag which would have been up at the top of the compressor and the took two
cans of the foam sealant stuff and filled it up all around the compressor and man you could
not even hear that thing, I was really surprised at how quite it was. :D

[HPLearner]

I had a customer once that took a small kitchen trash bag wrapped it over his compressor
and tied it down around the bottom of the compressor, then opened up a hole in the bottom
of the trash bag which would have been up at the top of the compressor and the took two
cans of the foam sealant stuff and filled it up all around the compressor and man you could
not even hear that thing, I was really surprised at how quite it was. :D

:D ...because it wasn't running anymore!