Dometic refrigerator replacement with a Norcold unit
This is long overdue, but I have finally put together a
report on replacing our Dometic refrigerator RM8501 (original RPOD equipment) with
a new, larger Norcold N4150.
The last post was in mid December in the “I Need Help”
section and was listed as “refrigerator gas operation help please”. We had trouble with the Dometic refrigerator
every time we used it over the 5 years we owned it. After our last trip, we could not get it to
work in LP mode and asked the forum for help.
We received a lot of good information, suggestions and help from other
forum members. We tried what you recommended but could never get it work
reliably and consistently. After much
thought and research, we decided to replace the refrigerator.
We had long talked about replacing the Dometic 3.5 cubic
foot fridge with something larger. After
weeks of looking, we could find only one model that would fit in our slideout
if we removed both our Dometic and Sunbeam Microwave/Convection oven. We ordered the Norcold N4150 refrigerator on
the advice of a local dealer. The dealer charged $2360.45 for the unit compared
to $1850 for the Dometic 8501. We picked
it up and transported it to our house.
The dimensions of the Norcold were almost a perfect fit although
the Norcold is 1.5” taller than the Dometic.
But the new unit required renovations of the fridge/microwave bay. The Dometic refrigerator and microwave were
easily removed.
The shelf holding the microwave was removed along with all
of the interior firring strips that lined the refrigerator bay walls. We did not have to relocate the LP line or
the electrical wiring.
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Original dometic and microwave
I installed ½” foil faced foam insulation on both side walls
and added the necessary filler strips to make the interior dimensions appropriate
to the new refrigerator.
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After insulation, the walls were covered with 1/8” Masonite and
all seams were thoroughly caulked as part of the combustion seal for the rear
compartment
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Insulated wall
I also added a 120v outlet and 12v charging center in the
upper right side that would be available over the couch and under the overhead
cabinetry. I used the original 120v outlet that served the microwave for the
power source and tapped into the existing 12v refrigerator power supply for the
new 12v charger.
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New 12v,120v charging station
I had to add a new exterior vent at the top of the
refrigerator bay as the new refrigerator completely filled the bay and needed a
hot air exhaust area at the top of the bay. Amazon had an exact duplicate of
the Dometic vent and it was an easy install. (The hard part was mustering the
courage to cut a BIG hole in the exterior wall!)
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New vent opening
The original top vent became the-center vent. I sealed it shut on the inside with vinyl that
I hot-glued to the inside of the vent. This
had to be done in order to enable proper air circulation – the bottom vent is
the intake, the middle vent is sealed off and the top vent is the outflow of
the heated air.
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New vent
The Norcold comes equipped with a single mid-mounted fan
that blows upward over the fins. I added
2 small computer fans at the top vent to insure positive upward and outward air
flow. All fans are connected with a thermo-switch.
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New fans
We measured the Norcold to make sure we could get it inside
the RPOD. We slid it into the opening
from the front with no problems.
Next, we had to seal the refrigerator bay to ensure that no
gasses (carbon monoxide or propane) could escape into the trailer. I created a combustion seal which is essentially
caulking all joints of the framing and all sides of the refrigerator box to the
walls. This is a messy and difficult job.
Access to caulk is only available
through the 3 exterior vents. All sides
of the refrigerator box have extremely close tolerances and are difficult to
reach due to the fins, combustion chamber, flue, etc. Some areas are almost impossible to get a
caulking tube access. Ultimately, I had
to attach 6” of clear vinyl tubing with a ¼” dowel taped to the end of the tubing
as a hand hold in order to apply the caulk where it needed to go. This was a major pain in the ass.
The next step was the installation of the interior
baffles. Norcold specifications require
that there be no more than 1” of air space between the exterior wall of the
refrigerator bay and the rear fins. This is to ensure proper cooling of the
fins by constant air flow from the lower vent to the upper vent.
I restricted air space by fabricating baffles. These baffles were made from 1/8” plywood and
attached to both the interior of the exterior wall and to the side walls of the
bay. Again, this was a real pain, but I
made it work. In hindsight, it would have been much easier to build and install
these baffles prior to putting the refrigerator in place.
Now that basic installation was complete, it was time to
make the final wiring (120v and 12v) and propane gas connections. I hired a
local mobile RV tech to do this part of the installation. He did a great job of extending the gas line and
connecting it, as well as finishing the wiring.
As part of the wiring process, I used a 12v busbar from Amazon to make
all of the miscellaneous 12v connections for the refrigerator, exhaust fans and
new charging center.
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Now, the bad news.
The refrigerator works perfectly on propane and 120v shore
power. However, after much testing, we
could not get the fridge to work in 12v battery mode. After hours of troubleshooting (reading the
Installation manual and making many calls to Norcold), we learned that our new
Norcold N4150 was NOT meant to be used in a travel trailer. It was designed to be used in an RV or motor
home (something with an engine). Neither
the dealer (who knew the fridge was going into a travel trailer) nor the
Norcold website ever mentioned that it was designed for an RV. The trailer
battery or the 7-pin connection will provide enough 12v power for the N4150 control
board to operate correctly on propane and 120v.
However, it does not have enough power to run the 12v battery mode heaters.
There is a component to the heaters that requires 14.4v in order to function. This
has to come directly from the alternator of an RV engine and is not available
from the 12v trailer battery or the 7 pin connection.
We did a lot of research with Norcold, the dealer and the RV
tech and decided it was impossible to make the unit work on 12v without adding
additional charging circuits and changing the wiring in our truck. We decided that, in reality, we never used
12v to run the refrigerator and we did not want to mess with our truck wiring.
Actually, a 2-way refrigerator (120v or propane) was totally acceptable to us.
Bottom Line
We just returned from a 3-week trip to Florida and the
refrigerator worked perfectly. The refrigerator is about 50% larger than the RPOD’s
stock Dometic and the freezer is huge. Both maintained temperatures accurately during
our trip, even though outside temps ranged from 37 to 80 degrees. The shelves and drawers made it easy to see
what we had stored. And, the airflow
inside the refrigerator is much better thanks to the design of the shelves.
We spent a LOT of money, time and effort to make this
transition, but we are glad we changed out the fridge. We like our new refrigerator and we love our
179 and hope to use it for many more years. https://postimg.cc/zLTh2jCx"> https://postimg.cc/LJbg8WTC"> I’m happy to answer questions or provide more in depth
details. I also have a Dometic 8501 that
works fine except on propane if you need a 2 way refrigerator or repair parts. We also have the original Sunbeam
Microwave/Convection oven we would like to sell.
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Vann & Laura 2015 RPod 179
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