New air conditioner considered

[AZ2Loop]

For those who have replaced older AC/heat pumps, I have an "Is it worth it?" kind of question.

Our 16,000 BTU is our primary unit. The boat has another 9,000 BTU (I think) unit as well. Both units are around 20 years old. The 16K unit is louder than I think it should be. It is the compressor noise that is loud. It is also located right between our master stateroom and the salon. So, the noise is somewhat annoying. It works, though. It works well. Yet we are considering replacing it, primarily in hopes a new 16K would be much quieter than our 20 year old one.
I have also wondered if a sound shield for the compressor is a good idea.
Have any of you added a sound shield to an older AC compressor? Was it helpful? Or have you replaced an older unit with a new one and do you feel a newer model would make enough difference to make it worth it?
It is an AquaAirrrr system, and it looks like the compressor is a Tecumseh brand from the mid 90's.
Thanks for any thoughts/suggestions. We'll likely be in warm/humid places most of 2021 so it will be run a lot this year.

 

[Comodave]

Yes, the newer ones are a lot quieter. How much is hard to define but substantially quieter. You should mount it on a rubber, or the like, pad to help stop mechanical structural born noise. You could line the cabinet with some Soundown insulation, ask them for their recommendations as to frequency of the noise and what insulation would work the best. Good luck and let us know how it works out. Maybe get a dB app on your phone and make before and after comparisons.

 

[STB]

Has it always been loud? Did it get louder in a relatively short period of time? Or, over time?

A lot of time HVAC noise is related to the installation. For example, my forward and aft units are exactly the same, except for the installation. My forward unit does everything right. My aft unit does a lot wrong. You could not possibly believe the difference in the sound. The forward unit sounds very modest. The aft unit sounds like a wind tunnel of airflow through which, somehow, one can hear the compressor.

W.r.t. my forward unit, the intake is large enough to breath freely low to the ground, and is recessed under a bit of a cantilever on the bed. The discharge is plenty large enough, connected by a soft insulated duct, and bends 90 degrees twice (once to go from horizontal to vertical, and again to the vents in each room), and discharges into two different rooms. (It would probably cool more efficiently with a higher intake, but where it is wins in the other ways).

My aft unit does everything wrong. The discharge is a short, uninsulated, hard metal duct coming straight out of the unit with no bends, discharging straight up. The intake can breath freely, but is directly exposed. Basically, there air is rushing out because the vent isn't large enough to reduce the volume, and the metal duct broadcasts all of the compressor and fan vibration, etc.

I'd be hesitant to replace a perfectly good air conditioner over a noise issue, unless the noise isn't original, e.g. grew over time or abruptly, and seems expensive or related to lifetime, e.g. a compressor failing vs a failing generic 12-volt fan.

Unless there was reason to believe it hadn't always been that way, I'd start with the installation. Are the vents large enough to have a reasonable airflow velocity? The ducts? Are the ducts hard or soft? If hard, are there soft segments near the unit to isolate vibration? Are the bends to projection of noise from the unit? Is there anything that can vibrate or project sound nearby? Can a hard enclosure be lined in a sound absorbing material (except for intake). Etc.

If it looked like there was a lot of reason for noise, I'd fix that first. If it fixes the problem, great. If not, the improvements will make the newer replacement unit seem quieter. Nothing lost.

Just to offer the color of my lenses, my own philosophy is that I try to avoid replacing anything that is working well and seemingly unlikely to fail, but when something isn't working well or is starting to show signs of sliding down the hilll, I either do whatever it needs to make it last a long time or replace it. I tend not to get myself into a heavy or repetitive maintenance situation with older equipment wherein I end up constantly fixing or messing with this or that. I value reliable a lot, but not necessarily newness.

 

[DrissZougari]

The newer compact units are much quieter however, I find that split units much quieter because of the compressor location in bilge.
Good luck,

 

[AZ2Loop]

Thanks for the responses so far. I appreciate the info!

gkesden, you asked some good questions. I have looked at the install. It has two decently sized ducts. The intake is large and allows great airflow. Basically it is installed as your forward unit and I see nothing wrong, other than the possible improvement of adding a sound shield.

You also asked about whether the sound has changed. I cannot speak for the first 23 years of operation, as we have only owned the boat for a couple of years. It has been this loud for those 2 years with no changes.

From others who posted, it sounds like newer technology is quieter, but hard to say if it will be an improvement by enough. Like you, I am hesitant to replace what is working, but I do think it is too loud. I wonder, though, if the sound is an indicator the compressor will fail, so perhaps it is time to replace it anyway. Hard to say.

I will add that if a new one is quieter by enough of an improvement, then it would certainly be worth it.

 

[HopCar]

I would imagine that the compressor of your old AC is a reciprocating piston type.
Most of the modern units use a rotary compressor that should be much quieter.
Twenty years is a good life for an air conditioner. You’ve gotten your money’s worth.

 

[ranger58sb]

We replaced vintage 2002 MarineAirrrr 16K BTU units with new Dometic Turbo 16K units, latter offering a sound shield option. I decided to NOT add the sound shields at first, since the new units were touted as already quieter. Yep, the compressors were nicely quieter, so we didn't bother adding the sound shields afterwards.

OTOH, wind noise was slightly louder, because the new units pushed more air faster. Sound shields wouldn't have done anything about that.

OTOOH, we could mitigate increased airflow noise by turning down fan speed, easy enough to do once a given area was either cooled or heated to whatever our set point was.

-Chris