sound proofing refrigerator....questions?

[Roonie]

I am about to do this project today. I have already taken the fridge out of the space.


and found that the refrigerator was basically rammed into the space denting the back and it has been riding on the bolt that holds the panel wall in place. In fact it looks like SMB actually shaved off part of the bolt holding the panel wall with a dremel bit just so the refrigerator could be rammed a little tighter in there. This has directly transmitted to the sound of the refrigerator transmitting to the entire van. When it turns on it feels like the entire van shakes with it every time it turns on. I can not sleep with the Norcold turned on at night so I am trying to remedy this situation before we leave for a week and half trip.



I picked up some dynamat at the local car audio store as well as reflextix at lowe's. My question is this....... should I dynamat the refrigerator entirely or should I dynamat the space the refrigerator sits in. I ask because the dynamat is $$$$ basically $10 a square foot. Dynamat is sticky on one side and will be stuck wherever I end up installing it. I think eventually the refrigerator will be replaced at some point which would mean if I dynamatted the fridge then say goodbye to the dynamat. Where as if I dynamatted the space then it would be there regardless what fridge is being used. Reflextix is cheap so I don't care where I put that.

Any thoughts on the best way to go about this from those who have done this before? Dynamat the fridge or space? reflectix the fridge or space? I was thinking of using both around it to maximize the sound proofness.

[Skywagon]

Dynamat reduces noise by absorbing vibration. So, I would Dynamat the cabinet and Reflectix the space or the refer. But before I did anything, I'd make sure that bolt head wasn't touching the refer or you're just pouring the Dynamat money down the drain.
Bill

[Roonie]

I am going to move the side cabinet wall over by taking the bracket off and cutting a slot in the bottom so the bracket can slide left to right freely when bolt is loose and this will allow it to be moved over by 1/2" or more if needed without relocating the bolt which happens to go through the floor.

Also going to cushion all points of contact. Like the rim where the refrigerator screws to I will put weatherstripping rubber gasket underneath so it has a cushion. Also putting rubber under any points it touches on the floor.

[Roonie]

So to follow up on what I did if anyone is interested and the outcome......

First I cut the bracket so I can adjust the wall. Moved wall out about 3/4" from where it was.



Then I dynamatted all the walls and floor.



Then I sprayed on adhesive over the dynamat on the walls and ceiling and applied a layer of reflextix.


I had to cut out the areas around the bracket so I could still fit the fridge in the space.


I put a piece of weatherstripping foam seal around the opening as I am trying to keep contact minimal between the fridge and the cabinets. I installed fridge back in as it went fine. I put foam sliders on the base of the fridge so it slid on the dynamt easily. Even with the reflextix it still has a 2" breathing gap on the top of the fridge for air flow to get to the compressor which is basically what it had before.


So the final outcome is that I reduced the noise by 50% if not more. Interesting note... the fridge is held in place by four screws through the face and two through the sides. I left the two screws out through the sides and kept the four screws on the face relatively loose. I noticed when I tightened them up it transmitted the vibration back into the van again. The fridge is secure and not going anywhere as it doesn't budge when I move it with everything loose so that is how I am going to keep it.

If someone wanted to reduce some immediate noise without pulling the fridge entirely out it can be done right at the face mount. Hope this helps someone.

Also this was probably the more expensive route to take due to the dynamat. One might be able to get same results with just reflextix I imagine? Noise bothers me when sleeping so I need it to be quiet. This fix should also have the refrigerator run less due to being better insulated now as well.

[Skywagon]

Nice job.
I'd be interested in reading your report on how much efficiency you think you gained. ie., how much less do you think it runs, or can you run it at a lower power setting?
I did a similar mod on a boat we owned and it made a huge difference. (Same basic fridge).
Bill

[BACKRDS]

I'd like to comment on efficiency and cooling problems with the Norcolds. I have a DC0051 (the 3.7 CF) and was having occasional problems where in some conditions it would run constantly and did not get below 50 inside. The manual for the frig says the small external fan should come on when the air around the frig exceeds 90 degrees. I checked mine by putting the frige in my sauna and slowly raising the temperature. The fan did not come on until it was about 125 degrees.

The heat that is removed from inside the frig needs to get dumped via the coils into the space behind the frig. When the temperature difference between the coils and the surrounding air is not much, the heat transfer is almost non existent so the frig runs continuously but doesn't get colder. To minimize that problem you need to maximize air circulation across the coils. SMB usually provides a very tight enclosure, with virtually no space on the sides. The bottom of the frig is about 1/2 inch off the shelf, and there is maybe 1 inch across the top. Air circulates by convection, and is "helped" by the fan if it gets too warm. If the van is very warm inside the efficiency is very poor. I put a thermometer with a probe behind the frig and was surprised to see how fast the temperature climes in that space when the frig kicks on.

I modified my system to increase the air flow, and I'll do a separate post, with photos, in several days. Bottom line, I hard wired the frig fan to a switch so I could have it go on well below the 125 degrees that I determined by my test. I also cut a larger opening into the support shelf behind the frig and added a second small, very quirt fan to further increase the air flow. The switch is ether OFF, one fan on, or both fans on. I kept the temperature sensor in place so I can monitor the space and the effect of the fans. The modification has made a big difference.

More soon, Steve