Soundproofing an Reverse Cycle AC Unit

Peas · #1 (**permalink**) 10-11-2011

I just had installed a Pompanette 16k BTU reverse cycle unit under my v-berth.
I have a vent that feeds the berth, and 2 more feeding the main salon and it works like a charm...BUT...it's kinda LOUD in the V-berth now...

I remember looking at every AC unit at the Miami Boat Show a couple of years ago, and this unit was by far the quietest at the time. It is sound insulated on the front by the air intake, but I'm thinking that being in the compartment under the v-breth, the fan and compressor noise is being echoed around, amplifying the noise inside the 'box'. Sort of like a speaker enclosure.

I'm looking for thoughts on whether or not if I built a box and had sound insulation lining the interior if that would help, or if given the large size of the return air grill, that it is what it is...and this is the price of staying cool and dry?

deniseO30 · #2 (**permalink**) 10-11-2011

Did you have to put it under your bed? err.. vee birth

christyleigh · #3 (**permalink**) 10-12-2011

Yup.... they are noisy. I don't know which is louder on my boat the AC or the Very Well insulated 75 hp turbo diesel

I would treat it like another engine compartment and line it with Sound Stop Foam or whatever they (Defender, WM, etc...) are selling now. On my last boat I lined the fiberglass engine compartment with 1" stuff that I believe back then actually had lead (the best) as part of the sound barrier and it made a BIG difference. BUT..... I think the sound proofing stuff is more designed to stop the higher frequencies like Diesel Clatter and such. It may not do as much for the Low Drone of a compressor and fan. But ....for a few hundred compared to the few thousand you just laid out I would give it a shot if it is really bothering you.

Allanbc · #4 (**permalink**) 10-19-2011

Ours is pretty loud too. Sound insulating is on this winter's list of projects. On the flip side, in the Texas heat, the sound is much more tolerable than lying awake sweating all night!

treilley · #5 (**permalink**) 10-19-2011

I have advised many folks to not locate the unit anywhere near the sleeping berth. Ours is in the salon with a vent in the forward cabin. We can close the door and this makes it background noise.

Your best bet is to relocate if possible.

You are right that the intake will allow sound to escape even if you insulate the unit better.

Peas · #6 (**permalink**) 10-19-2011

Quote:

Originally Posted by treilley

I have advised many folks to not locate the unit anywhere near the sleeping berth. Ours is in the salon with a vent in the forward cabin. We can close the door and this makes it background noise.

Your best bet is to relocate if possible.

You are right that the intake will allow sound to escape even if you insulate the unit better.

Thanks Treilley,
There really wasn't any other place to locate the unit, without having to take out water tanks or lose valuable storage space in the galley...so unfortunately, the V is where it went...

That said, on HOT nights, when it does need to be left on, I figured I could always crash in the salon. I was just wondering if I spent the $500 for vibration mats and soundproofing foam, if that would help given the 12"x12" intake vent...that you obviously cannot seal....

Cptken · #7 (**permalink**) 10-19-2011

If it is vibration noise that is being amplified, bigger rubber mounts might help. If it is just the ambient compressor/fan noise, not much you can do. Might want to try a baffle between the air intake and the unit, may keep some of the noise under the berth rather than radiating out. Try a cardboard template first before you build anything permanent.

saildog1 · #8 (**permalink**) 10-20-2011

I get most of my noise from the water pump. my compressor unit is mounted in the cockpit lazerette and the condensor is under the Vee berth. So I hear blower noise and a humm from the water pump.

deniseO30 · #9 (**permalink**) 10-20-2011

Someone in the HVAC trade could relocate the compressor and reversing valve to another location of the boat then it would only be fan and controls under the bunk... but not something a DIY should try... and, all warranties would of course be void...

GaryHLucas · #10 (**permalink**) 10-20-2011

I have had pretty good success over the years quieting noisy equipment down. I have found that mastic self-adhesive pads work on flat surfaces of sheetmetal and plywood, reducing transmitted sound. A few years ago I installed a 15 HP vertical high pressure pump in a quiet shipping area of a plant. The union was going to file a grievance over the noise. I took a cardboard drum, cut out the bottom and lined it with a 1" foam and mastic pad that I got from McMaster Carr. Everybody thought it was joke, but the noise reduction was huge. I could then hear the noise made by high pressure water shooting through valves and piping. Some 1" thick black neoprene pipe insulation made a big difference. It's still running after 7 years, and no complaints.

There usually isn't one source. I find that adding sound proofing a little at a time then listening carefully lets you figure out what the biggest source is, and you can focus on that.

Gary H. Lucas