Rather than hijack Warbird's thread to continue a conversation I started with Jim, let me start over here. In my opinion the noise level from our Coleman Mach 8 Low Profile 9,000 BTU air conditioner is simply unacceptable. I downloaded a decibel meter APP and took some measurements after a four day local trip spent trying to talk loudly enough to be heard over our AC unit. What I had was 66 decibels on low and 72 decibels on high. I know those levels are not likely to damage our hearing, however, they are really irritating inside the camper. Outside it is fine. I should note this is all with a non-ducted system, if you have a ducted system there are aftermarket "air silencers" already on the market that do reduce noise level.

After taking those measurements I did a good deal of researching on the Internet as complaints about low profile units and noise level in small RVs like van campers and truck campers appears to be commonplace. I proceeded first by simply comparing the noise level with the compressor running or not running and surprisingly what I found was the decibel level did not increase with the compressor running. The unit is just as noisy on fan only.

Next I was curious if there was anything I could do to the air distribution box (the inside cover) to improve things. I first removed the filters so any turbulence they created was gone and again no change. Next I removed the deflectors on each end of the box to see if eliminating turbulence around them would improve things and it did not.

Next step was to add a layer of sound deadener to the inside of the air box as one blogger suggested in a YouTube video. In that video he alleged he was able to tell an improvement but did not supply any decibel numbers. I found no improvement at all when I did it.

Now here is what I know. There is an aftermarket kit available that is tied into the wiring for the compressor fan that slows the fan on low speed, however I am reluctant to go in that direction since the compressor operating does not change the inside decibel level. Coleman also has a relatively new Quiet model that looks very good on YouTube with dramatic reductions in decibel level, however it is not a low profile unit and is a 13,500 BTU unit. I do, however, like the fact it can include a air box that can be blue toothed to your phone and you actually set a temperature rather an simply hotter or colder.

Finally, there is a company located I believe in Indiana that has developed their own low profile quiet unit that reportedly reduced amp draw by 50% and drops decibel level into the 50s. As I understand, it is now available on some motor homes and they also will install it on your own RV following a down payment and making an appointment. As you can see here, the price is a shocker https://www.upfittersresource.com/co...-benz-sprinter.

I'm still thinking!

Steve

 

I have been looking at that NDQ unit for awhile, it draws the same current as the coleman 11K unit on the rig now but it would be about 3" shorter. I'm very limited since my AF 992 has a skylight directly behind it so at last measurement the penguin and mach 8 won't fit. I kicked around a minisplit but seems like a large project.

 

I know many folks out West may not see the need for an air conditioner, but for those of us living in the Southeast it is a bit harder to just jump in and drive a couple of hours to gain some elevation and even then our elevations here are not that high or that cool. My wife and I were just discussing whether it would be a better investment to upgrade our AC or invest in a solar system. Her point well taken is even if dry camping we have our genny with us as otherwise the temperatures are unbearable.

I would spring for the NDQ as I am impressed with the quiet level of operation, but the worry I have is oversizing may lead to short cycling of the compressor so we end up cool enough, but clammy. That being said, give me a smaller version and I will write the check. I know the specialty unit I linked is incredible, but near $3,000 is a bit steep for a rooftop AC.

Steve

 

I'm in phoenix. We do the same, in under 2 hours I can be at 7600' but it can still get warm so we get under the trees and that's detrimental to my solar production. Seems that people use that unit on sprinter size vans without much issue, 1 feel my 11k short cycles but we seem to tolerate much warmer temps unless the humidity is high. I agree on the price of that unit, I have considered a mini split with a cassette but my research has led me to thinking they don't like the condenser unit far off level so that may be an issue...along with mounting.

 

I do think mounting a split system would be a real challenge. Humidity here in Tennessee can be a bear

 

Ok, this is my first truck camper and last summer was my first trip with it. I was surprised how noisy the AC was compared to my travel trailer. I guess it's common.

 

There is also typically a lot less space in a cabover for sound to travel before reflecting versus a trailer. Same goes for padded and carpeted surfaces. Also less room means ears are stuck being closer to the roof unit.

 

All true, however, the AC in our 04 Hallmark was substantially quieter. I think slowing the evaporator fan would make an improvement as Coleman makes a selling point about CFM, however I am afraid the evap coil would ice up. There is also very little room in the air box so the air has to make rapid turns in tight space. Dometic's Penguin usually gets a quieter rating and I would give that a try, but I think the 13.5 output is overkill and it carries a price tag that is a little much just to try something. I think the air box on the Penguin also would be low enough to hit the fridge door on the Northstar. If Coleman comes out with a quiet model in this size, this one will be out the door for us!

Steve

 

I agree about the noise. We have a Dometic Penguin II 11K unit in our Host and it too is very loud. We are leaning towards the 13.5 NDQ partially because anywhere we have been this summer in the Midwest has been unbearable and the 11K cannot keep up. My thoughts are the comfort of a camper in the Southwest is far better with working AC that's bearable to be near than solar. We have 680 watts of solar on our roof and it rarely charges fast enough to keep up with the demands of an AC unit. My little Honda 2200 is way faster and easier to run (although I'm thinking of switching it to a Predator 3500). While you can argue solar is "free", the cost to set it up is far from cheap and the cost to make enough usable energy in battery costs/ inverter- would be a hard sell to see a return on investment (we have 720 amp/hours of LiFePo batteries). That's a lot of gas you could buy. Id get the AC and possibly a small desk top dehumidifier and small fan to keep circulation. We love ours

Just my thoughts.

 

If you get the NDQ please report back. I would like to see what you have to say.

Steve

 

Our Mach 8 Cub (9,500btu) is very loud and way too big for our smallish truck camper which causes it to short cycle and doesn't pull out much of the humidity.

I did install a MicroAir EasyStart which, though expensive, was cheaper than pairing another generator or upgrading the Champion 2,000 inverter to a Honda or even a Champion 3,500.

I wonder if adding a vent just under where the air is being forced down and then squished out the two vents would relieve some of the pressure and maybe lower the noise a little? In out floor plan, the rear vent blasts at a wall that is less that 2 feet away and the other vent blasts directly into the cab over.

 

Leo,

That has already been tried. You can find it on YouTube. It did not make any improvement. I also tried it with the entire air box off and decibels were the same. The fan is just too darn loud!

Steve

 

Dang...ok. We don't need 9500 BTUs either, half that would be enough.

 

I agree. I think what we need is a 7,000 BTU or thereabouts quiet low profile rooftop.

Steve

 

As my Coleman aged it finally got the point it would not start unless it was on shore power. I looked at the Micro Easy Start if I was going to pay that much money I might as well buy a new one. This nagged on me for some time and with summer coming on I was close to buying a new AC. Then I tried one more approach. Instead of firing up my Onan genset, I used my house batteries to start the AC and it worked. Then I wait on the AC to cycle to compressor off and I started my genset and bingo worked perfect. Years later I sold that Truck Camper and showed the guy how to do, that was 3 or 4 years ago and its still working for him.