Insulating Dometic fridge?

[LookinUp]

Somewhere I think I saw a video where someone covered their Dometic 12 v fridge with reflectix. Has anyone done this or used some other material to do so? Is it something to even consider? I have a 50 L fridge and on a recent road trip kept spare blankets, towels, etc on top and could feel the cold on them when I removed them. Thanks in advance!

 

[Spaceman Spiff]

I have a Norcold upright refrigerator that I insulated with ~3" of isopoly (sides, top, bottom, & part of back).  Makes a big difference.  I could only get ~ 1/8" of foam on the door.  Sternwake has a good writeup on insulating his refrigerator.  Reflectix would only be useful if direct sunlight hits the refrigerator.

 -- Spiff

 

[BradKW]

I saw this on a youtube channel I watch...took some googling to find the product, I think it's new and not yet available for every model size:

[img=400x400]https://images-na.ssl-images-amazon.com/images/I/91iGPAiHLKL._SL1500_.jpg[/img]

Dometic CFX-CVR35 Insulated Protective Cover

 

[SternWake]

Xtra insulation is wise.
I used 3/4" foil backed foam board and flexfix foil tape on my fridge Exterior and cabinet interior.

Of equal importance to efficiency is proper ventilation to cooling unit. A fridge does not.force things cold, it.removes heat. So this heat must be released to atmosphere.

So extra insulation is as beneficial as insuring the condenser can easily . expunge the heat it harvested.

When both are attended to a good fridge becomes a great fridge.
When neither are attended to, it will consume much more electricity to perform same task.

b

 

[Oberneldon]

I put Reflectix on my Engel Fridge. The Engel is painted dark brown and sits under my Prius hatch. Since I use my privacy cover I did not have height room for foam insulation.

Even with the privacy cover over my fridge with Reflectix, when I remove the Reflectix the top and sides of my fridge are much cooler.

I know it's not the best but works for me.

Brent

 

[ldmccain]

Had some left over 1/2 inch foam and aluminum tape. [emoji1]

Wandering Larry

 

[JT646]

My 3-way Dometic fridge is built in but I also added insulation--replaced the door panel with 2 layers of reflectix.  In additon I glued some on to the inside of the door.  This did help--I have been able to reduce the cooling setting from 5.5 to about 4.5 and still maintain the same temperature.  As Sternwake noted, proper heat removal is also important.  I've read where people have added a mini computer fan to increase heat removal from the coils.

 

[MrNoodly]

Here's the insulated box I built for my Dometic. Two inches of foam all around (except for the cool-air-in and warm-air-out ports) with some decorative Reflectix on the outside. Actually, the Reflectix on the lid reflects sunlight coming in the windows, so it's not totally just for looks.

https://rollingsteeltent.blogspot.com/2014/06/rst-renovation-project-2.html

 

[SternWake]

Love the foamboard covers, but they do get beat up over time.  When I first was insulating my Vitrifrigo upright fridge, I had 3/4 inch foamboard temporarily taped to sides while fridge was running overnight. Temp readings on outside of foam when I removed it was 82 f, and an immediate reading on fridge wall when I removed foamboard panel revealed 62F showing how effective more insulation is.

Those thinking of doing this on an chest style fridge might consider protecting the foamboard insulation to help retain R value.
Bamboo skewers can help hold the foam edges together when taping the corners, and reduce cursing when doing so.

I really like the Nashua Flexfix tape, as it is stretchy and durable, unlike the thicker foil tape with the backing which rips and punctures easily. Mates with reflectic nicely and can be found in home despot.

https://www.amazon.com/Berry-Plastics-684098-1-89x120-3YD-Flex/dp/B000WEMH8M

Those fridges that use a danfoss/secop compressor can add another computer fan to the vent port of a chest style fridge or in the cabinet of an upright fridge  to vastly increase heat removal.  A Noctua NF-f12 fan consumes only 0.05 amps and is very quiet.  I replaced the 120mm fan provided with my Vitrifrigo fridge on my condenser with one of these, and installed it to push air through condenser rather than pull it.  not only did amp draw of the fan decrease from 0.12a to 0.05amp, the Noctua pushing air through condenser is so much more effective it reduced the time the compressor needed to run( duty cycle)

The Waeco compressor used in Newer dometics seems to be a clone of the venerable Danfoss Secop bd35f, and should likewise be able to have another fan easily added for additional heat removal from condenser.
waeco:

Danfoss bd35f:

Here is Danfoss's instruction sheet:

http://files.danfoss.com/TechnicalInfo/Dila/06/bd35-50f_electronic_unit_ac-dc_04-2009_ei100g402.pdf

I'd think the waeco is similar in the ease of adding another fan to assist heat removal, but am not sure.

Also consider the dust build up on fan blades and condenser fins.  This was so extreme on my upright fridge I added an air filter on the air intake below my fridge, and it loads up surprisingly fast.  Mine seems to be similar to dryer lint in consistency, and even with the filter there is some build up on leading edges of my Noctua fan and condenser fins which I clean every 8 to 12 months.

http://www.homedepot.com/p/Vent-Fil...gclid=CLa87reZiM8CFcVcfgodEEAG1w&gclsrc=aw.ds

It is said dust build up on fan blades can diminish airflow by 30% pretty easily depending on fan design.

So insuring best possible heat removal vie proper unrestricted ventilation not only increases efficiency and reduces draw on the battery, it also increases compressor life.

In the danfoss data sheet above, notice the wire gauge recommendations are much thicker than one would thing a maximum 5 amp circuit requires, and that they say to not share any power busses with other devices, and to instead run right to battery with a fuse at the battery terminals. This is not only from a voltage drop standpoint but a power surge standpoint.  When some devices are turned off a surge can backfeed back through circuit back to the filter(battery) possibly damaging the compressor controller( cumulatively over time)

These portable units need to come with a Ciggy plug, but the quality of these plugs is generally horrid, and the wiring to these ciggy plugs is only 16awg, much much less than danfoss recommendations, and does not take into consideration that the 12v ciggy receptacles in most vehicles are already underwired with many voltage dropping connections from the long distance from vehicle battery to 12v receptacle.

So the higher the voltage reaching the compressor controller, the more efficient, yet these ciggy plugs and thin wiring are dropping voltage to the compressor controller, decreasing efficiency, and then there is the unreliability of the ciggy plug itself, when it inevitably wiggles loose.

AND the stress of the ciggy plug working loose while the compressor is running has to be cumulatively stressful to the circuitry within the compressor controller.

So improvements can also be made with delivery of electrons to the compressor controller not only for efficiency, but possibly longevity of the electronics in the compressor controller, simply by getting rid of the Vile ciggy plugs and receptacles used to power the fridge.

The Noctua NF-f12 fan is truly impressive, especially when mounted to push air through a restriction such as a condenser.  It is significantly louder when mounted to pull air through the condenser, and much less effective.

i've not personally opened up a chest style fridge and do not know how easy or hard it is to access the compressor controller or swap out a fan.  Swapping out the fan on mine required a very long phillips screwdriver to reach 2 of  the screws. but a 90 degree screwdriver could likely have done it as well.

Relocating fan to other side of condenser on mine allows easy access for cleaning.  My extra insulation on fridge and cabinet interior allowed this relocation, otherwise there would not have been  enough clearance for the fan to pull sufficient air.

I do not know how close the condenser is to the sides of a chest style fridge or whether it can be relocated, but the airflow direction can be reversed by flipping the fan.  Pushing air through a restriction is so much more effective than pulling it through, and quieter.  I am not sure why they do not do this at the factory.

The 120mm fan provided with my VF fridge is rated at about 72CFM and the Noctua is only ~53CFM, yet mounting the Noctua to push works so much better, is quieter, and consumes less electricity while being more effective.  The Noctua fan has a higher static pressure rating, meaning it does better when there is a restriction in front of the blades.

Next month it will be in near continuous operation for 4 years with only ~2 weeks off per year.

Here are a few Pics:  

Here is looking down on the top of my Danfoss as mounted on my VF as it came originally.  one can see the 120mm computer  fan mounted between condenser and compressor, airflow direction was originally from right to left, and still is but can be reversed.

The above pic one can just see 3 vertically oriented fins on the back of the compressor controller.  heatsinks.  Air from fan should flow over these to keep the electronics cool. 

In the Below pic, one can see the green circuit board to which is mounted a resistor, on the thicker  blue wire.  This 270 ohm resistor is to increase compressor speed from 2000 to 2500.  This aids in faster heat removal on initial cool down or when warm items are placed within.  The slowest compressor speed which still allows less than a 50% duty cycle is most efficient.  I removed this resistor to slow rpms to 2000 and amp draw when compressor is running is less, starting at 2.9 amps or so and decreasing to 2.2 amps about 5 minutes later when it cycles off. It was about 0.5 amps higher with resistor installed.  The actual amp draw varies with the voltage the compressor controller receives. Most chest style fridges with Danfoss/Secop units will have additional circuitry somewhere inline on this blue wire to automatically control compressor speed.  the maximum rpm on this compressor is 3500 and at this rpm it can cool a fridge more than 2x the size of my fridge.  Bigger fridges  like BradKW's, step upto the Danfoss BD50f compressor.

The thinner red and black wires run to the condenser fan.  you can see the thicker wires are the main power leads and have two thinner wires butted right up against them, these wires are for the internal LED light inside fridge.

Inside the fridge, before the magnetic reed switch, with turns light on and off with the door, I tapped these wires to run a 40MM 0.03amp Sunon 12v fan, which runs 24/7 and helps to cool items within faster and keeps internal temps much more even.  It does not decrease overall amp draw however. The fan itself adds some small heat load to the fridge, which Is why I found the lowest amp draw fan I could at just 0.03amps.  High CFM not required.  Sunon said this fan would not work in this application.  It has been working for nearly 4 years now.  Here it is just hanging on a bamboo skewer blowing into the freezer compartment.  Not ideal but good enough. This internal fan allows me to use a setting of about 2.5 of 7 to maintain sub 35f temperatures inside the box.  Without it it requires a setting of  close to 4 of 7 to maintain sub 35f most everywhere inside, but the range of temps would be 27f on floor to 42F in the far back just under cooling unit.  With the internal fan there is only a ~2 degree swing from warmest to coolest spot in fridge.   With more 'overhead' on the dial I could more easily turn it into a freezer, but never have. I don't really employ the  small freezer portion and have removed the door. I only make ice and keep an ice pack frozen in there.

I made a cooling unit tunnel so that all the Noctua's airflow has to flow over compressor and compressor controller:

When fridge is inside cabinet the fan cannot recycle any air that the condenser has already heated.  it can only pull cooler filtered air from the other side for maximum efficiency. Warmed air is either purged out a louvered vent in a conversion van sliding window or into an adjacent section of cabinet which houses my other electronics and which has an 80Mm fan exhausting 24/7.

 Sliding my fridge into the insulated cabinet is a Very tight fit in an awkward spot because of my 3rd captain's chair directly in front of fridge, so this cooling unit tunnel also protects the cooling unit from installation stresses.  I adhered some peel and seal roof flashing to the interior and exterior of this stainless steel cooling unit tunnel to help dampen sound from compressor, though the sound was about 1/3 less than my previous Norcold fridge that used a Sawafuji Swing compressor, that failed after 5 years of near continuous use.  The aluminum  L brackets are just riveted to the stainless 'tunnel'.  I hold it to the insulation on fridge body with more Nashua flexfix tape and just cut the tape when I pull the fridge to clean the dust from fan blades and condenser fins..

Before filter, ~ 6 months of dust build up:

Hope this is helpful to readers who seek to increase efficiency of their danfoss based compressor fridges, and possibly Waeco.

My fridge  in average 75 f ambient temps consumes somewhere between 12 and 18 amp hours in a 24 hour period, but of course the amount of door openings and the contents of the fridge can swing the consumption numbers well outside this average.  In ~65f  ambient temp Averages I have seen as little as 6.5Ah consumed in 24 hours to maintain sub 36F internal temperatures.

 

[MrNoodly]

Love the foamboard covers, but they do get beat up over time.

Which is why I covered my foam with plywood.

 

[TooManyDogs]

$18 dollars and 2 hours later, my insulated "box" is still not completed. Might've been cheaper to buy the pre-made fabric bag for my Whynter frig from Amazon.

 

[SternWake]

$18 dollars and 2 hours later, my insulated "box" is still not completed. Might've been cheaper to buy the pre-made fabric bag for my Whynter frig from Amazon.

DIY vs Buying a substandard made in China product infused with toxic chemicals for your sniffing, bowel voiding  and DNA mutating pleasure.

Define 'cheaper'

 

[Silver6gen]

  

Can you repost your photos?  Photobucket decided to boot the photo part of their site.... I know...