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Norcold Fridge improvements

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LRUCH

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Norcold Fridge improvements
« on: October 13, 2022, 11:15:00 pm »
The last week of August I was camping on Lake Livingston, TX and the peak outdoor temp was 104F and my PC was in full sun.  I noticed a few things about my fridge.
   1.  The Freezer was higher than normal and hovering around 28F. My ice cream was getting soft.
   2.  The Fridge was much higher than normal and hovering around 43F.
   3.  I had already raised it to number 6 and it running on 120V electric.
   4.  The cabinet around the fridge was getting hot.  On the right side (facing the couch) it was easily 5 (probably 10) degrees warmer along the portion of the wall which was between the back of the fridge and the outside RV wall.  On the left side where the burner is, this backs up to my shower and it was at least 10 (probably closer to 20) degrees warmer along that 4 inch wide strip.  I can't give precise numbers because I don't have a IR camera to measure surface temps.  Side Note, I had also noticed this same section of the walls to be cold when in Illinois in 15F freezing temps.
   5. I checked it from the outside and there was a bit of a draft in the bottom (Kleenex test confirmed this), but it was really hot in there.

A bit of history here.   I bought my 2010 2900D in 2020, so it was 10 years old at the time.  There were no appliance insect screens on it at all and I found some mud dauber nests in the fridge back (and furnace!) and cleaned those and all dust/dirt out the first week I owned it.  Very soon after, I added a "Fin-Fan" that attaches to the fridge fins and it really helped keep an even temp throughout the fridge.  I was happy.
https://www.amazon.com/DutchAire-RV-Refrigerator-Fin-Fan/dp/B089BWZ3PX   

Up until August I never parked in such a hot spot with zero shade on my fridge.  But, this told me I needed to improve the situation.

Hence, I thought I would writeup my "rebuild the fridge" adventure.  I know this will be lengthy, so I'm breaking this up into 4 parts.
   - this posting with history, original config and what I discovered
   - what I insulated and installed
   - my test results, before and after
   - and later I may add a 4th posting if I decide to add exhaust fans in the fridge roof vent

I did a lot of research and found that other RV owners who encountered the same issue benefitted by:
   - cleaning the back of the fridge and the the inside of the cabinet
   - adding insulation
   - improving the baffles, or adding them if missing
   - adding fans, sometimes at the bottom, sometimes at the top and sometimes both.

So I decided to pull the fridge out and see what I found and what I could improve.  I removed the doors.  I emptied the fridge of as much as I could including all shelves & bins, because I knew it would be heavy. I removed 6 screws inside the RV, and 3 in the back.  After disconnecting the 120V, the 12V and the propane (as well as turning off the propane at the tank FIRST), everything was disconnected and the fridge was moveable.

With the anticipation that it would be heavy, I had 2 large buckets upside down in front of the fridge and slowly wiggled the fridge out.  However it was stuck.  I could only move it about an inch.  After about an hour of frustration I decided to give it a jerk and dislodge whatever was holding it..  That worked.  The fridge came out and I set it on the buckets... caught my breath and then set it in the middle of the RV on the floor. 

It turns out,,, there were LARGE mud dauber nests in the gap between the fridge and the ceiling.  The fridge was glued in place by these nests.  I threw out more than 2 pounds of dried mud nests as well as a large handful of paper wasp nests.  They were all up and out of view and reach from the outside access door.  One small one was inside the heating tube.  One was embedded in the rear fins.

The rear wall wallpaper was peeling off the wood baffles.  It had evidently got hot enough to release its glue.  You can see it curled up in the photo below.  The baffles themselves were almost up to spec.  I found a large gap on the right side that should be closed to eliminate wasted airflow that should pass the fins.  The parts of the wall that are visible to a person looking through the door are spray painted black.   At first I thought the heat had charred it, but it is black paint. The insulation is all un-faced fiberglass and fills the left and right side cabinet gap.  There was NOTHING on top except the carpeted ceiling.  There was no insulation on the side walls or outside wall behind the fridge.  I totally understand why there is nothing on the outside wall, you want as much heat dissipation as possible.  But, the side walls are basically my interior walls that I found be transferring a lot of heat.

The back of the fridge and pipes were not too dusty.  The top was very dirty.  The fins were not bad, except for the one nest.  There was only a very thin layer of insulation on the back top half of the fridge.

See attached photos of inside the cabinet and back of the fridge AFTER I cleaned it out.  Sorry, I didn't think to take pics before cleaning.
Larry

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LRUCH

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Re: Norcold Fridge improvements
« Reply #1 on: October 13, 2022, 11:19:41 pm »
Now that everything was clean it was time to improve.  I had learned that the top, sides and back of the fridge should get as much insulation as possible, but keep the insulation away from the fins, pipes and heating tube.  So, I added:
   - nothing to the sides as there was no room.
   - foam board insulation (from Lowes) in the gap between the fridge top and the ceiling with, and put flexible Reflectix over the face of it from the front of the cabinet to the edge of the roof vent, with all edges sealed with aluminum tape.  The Reflectix ensures a smooth surface so that the fridge slides back in easy.
https://www.amazon.com/gp/product/B0009XCJA2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1 
   - 2 layers of 1cm thick UXCELL heat insulation on the side walls between the back of the fridge and the outside wall, as well as across the bottom.   As a precaution I only put 1 layer along the heating tube to keep the recommended distance as per the Norcold installation manual.  I added a 3rd layer on the right rear side wall as there is nothing that gets hot there. I wanted to make that section as well insulated as possible for summer and winter.  You can see this deviation of thickness in the photos.
https://www.amazon.com/gp/product/B07V6TNF6B/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1
   - 1 layer of the 1cm UXCELL on the back of the fridge,,, mostly the blank middle section and some of the top, while being careful to not block fin air flow.  I felt that a 2nd layer would be too close to the pipes.
   - a Norcold fan control thermistor.  I may use this to control future exhaust fans mounted in the roof vent. TBD.  It was only $12 on Amazon and I installed it as insurance.  It needs to be mounted in a position that is not accessible when the fridge is installed, so I needed to do it now, or take out the fridge again to install it later.
https://www.amazon.com/Norcold-618093-DC-Fan-Thermostat/dp/B004RCX95U/ref=sr_1_25?crid=28TQQM1JCJFQ1&keywords=norcold+thermistor&qid=1665716349&qu=eyJxc2MiOiIzLjczIiwicXNhIjoiMy4yMiIsInFzcCI6IjMuMDkifQ%3D%3D&sprefix=norcold+thermistor%2Caps%2C101&sr=8-25
   - a pair of wires for the future roof fans
   - a pair of wires for the thermistor
   - a small baffle created out of the UXCELL to block the gap on the Right Rear side (you can see it just above the red and white wires). ITs a bit bigger than the gap and when the fridge is installed it squeezes up against the fridge read wall and seals off the air gap.


Once this was done, I reinstalled the fridge, attached the doors and all connections.  Then tested the gas line  with soapy water and was ready to turn it on.  The install was much easier than the uninstall.  I got a friend to help lift, and with just a little bit of wiggling and slow pressure it slid right in place.

In my next post I'll discuss the performance results.
Larry

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LRUCH

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Re: Norcold Fridge improvements
« Reply #2 on: October 13, 2022, 11:20:54 pm »
To test the performance improvement, I wanted to compare before and after as "apple to apple" as possible.  I was also running out of really warm days, so only 2 of the tests (both electric versions) are almost identical outdoor temps.   The 3rd test was on the warmest day I could find, in the high 80s.  I personally tend to run over to the storage facility and turn on the Fridge at noon the day before I leave on a trip, and then let it run through the night so that I can load up the next morning.  These tests reflect that habit.

All tests start at noon with the fridge at indoor temp and the interior Fin-Fan ON and the Norcold set to "4".  The indoor temp and outdoor temps are almost equal as well.

The first test: 
   Baseline.  Before cleanout and improvements
   120V electricity
   Air conditioning OFF (I didn't want the A/C to "help" the fridge cool down in any way)
   See graph with HEADING = "Cool-Down, Electric, No A/C, BEFORE Rebuild"

The second test:
   After the cleanout with added insulation
   120V electricity
   Air conditioning OFF
   See graph with HEADING = "Cool-Down, Electric, No A/C, AFTER Rebuild"

The third test:
   After the cleanout with added insulation
   LP Gas
   Air conditioning OFF
   See graph with HEADING = "Cool-Down, LPG, No A/C, AFTER Rebuild"

At the top of each pic is the raw data for temperature and humidity of OUTDOOR, INDOOR, Freezer compartment and Fridge compartment.  I placed the temp sensors on the middle door shelf of the fridge and the top door shelf of the freezer.  These 2 positions were the warmest areas back on the 107F Texas day.

At the bottom of each pic is the 4 temperature readings graphed from start time (noon) to the point of reaching the goal temps of 35F for the fridge and 12F for the freezer.

I'll let you drawn your own conclusions, but here is what I noticed.

1. On electric, the improvements reduced the time to reach the goal temps by 2.5 hours (when starting from about 93F).

2. On gas it reached the goal temp 3.5 hours sooner, which is better than on electric.  That was expected since gas produces a higher heat and improves the ammonia/helium cooling effect and definitely better than before the improvements. I wish I had captured a before test for gas, but I was limited on the amount of time I could dedicate to this.   Also, I rarely cool down the fridge on LP gas because my storage space has free electricity and they frown on the use of propane on site.

3. Before the improvements (test 1) the fridge was struggling to get the fridge and the freezer down to the goal temps. The lines are very flat.  After the improvements (tests 2 & 3) there is a clear downward curve of the freezer temps and once that reaches the goal it holds level and the remaining chilled helium begins to cool the fridge, so the fridge temp then takes a downward curve.

4. If you compare the indoor and outdoor temps for all three tests, it is obvious in test 1 that the back side of the fridge is heating up the PC interior via the hot walls.  The indoor temp (orange line) rises above the outdoor temp (black line).   After the improvements the 2 lines are almost identical.   This added indoor heat is something the air conditioner would need to overcome and push out of the PC.


What's next?  Well, it is a bit late in the year for me to camp in full sun over 100F so I may need to continue this adventure next year.  I have the wires and thermistor in place to mount fans in the roof vent to pull out heat if needed.  I chose to only do exhaust fans and not intake fans.  I'd rather pull the heat out than try to push in cool air as that might also push external air into the PC interior.

If I do need to add the fans, I'll probably put in a DPST switch so that I can run the fans on AUTO using the thermistor, or on MANUAL with a speed controller.  The fans I have for this are 3 super quiet high speed 12V computer exhaust fans.  Full speed might only be needed on the hottest days.  I don't think sound would be a problem as I've tried to hear them from inside after temporarily connecting them up while I had the fridge out.  I couldn't hear them.   But while boondocking I want to be able to minimize power consumption.  Stay tuned as I'll update this thread when summer returns.

Larry
« Last Edit: October 14, 2022, 09:28:55 am by LRUCH »
Larry

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Taildragger

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Re: Norcold Fridge improvements
« Reply #3 on: January 03, 2023, 11:12:27 am »
Good information!  Plenty reasons to perform an in-depth cleaning ot the refridgerator compartment.  I also purchased a used Phoenix Cruiser.  Wasps nests were in every conceivable crack and cranny.  From the narrative, I am motivated to pull my fridge out - just for cleaning.  Considering the nests were in the recesses my units rear view mirrors, fender wells, ..........everywhere  I am prepared to make a discovery that I didn't know was possible

Thanks for the pictures