Replaced Norcold 3-way with efficient AC/DC electric fridge

GeoMars

I removed the Norcold 3-way and installed an Indel B TB51A in a slide-out drawer. The Indel B has a similar format to the ARB, but has a slightly smaller length (left-right in photos). This allows it to barely fit inside a the existing cabinet where the Norcold was installed. Power consumption, according to 4x Overland Adventures (https://www.4xoverlandadventures.com/2017-winter-fridge-shootout/4/) averages 0.5 amps to maintain a temperature that keeps the bottom items frozen. This is the same power usage as the ARB that they also tested.

Installation was extremely tricky because clearance was so tight in all 3 dimensions. Installation required:
(a) Removing the Norcold.
(b) Installing sliders that wouldn't take up so much room the fridge wouldn't fit. This required mounting drawer sliders horizontally under the tray. Horizontal mounting substantially reduces the load rating of slides, so I had to use ultra heavy duty slides.
(c) Assembling front, back, and sides to make a box to enclose the fridge on the sliding tray. This was the tricky part, because the box had to be large enough to hold the fridge and small enough to fit in the opening and clear the lip of the screen door.
(d) Installing rigid foam inside the box and around the fridge (except for fridge vents) to increase insulation and keep the fridge in place.
(e) Installing marine "slam latch" with finger pull to hold drawer in place when closed.
(f) Putting insect screen and wire grid inside vent openings to keep out bugs and rodents, since the fridge compartment now opens into the T@B when the drawer is pulled open. 

Photos show the new drawer closed, open, with the fridge open, and the screened vents.

The new fridge is 4 liters smaller than the original Norcold (47 liters instead of 51), but items can be piled in without falling out when the door is opened.

Tabaz

VERY nice job! Good to know this can be done. Thanks for trailblazing this mod. I'm guessing some of us will have to do this when our Norcolds finally die.

irvingj

Very professional! After we sold our T@B we got a Sprinter-based RV that had a 2-way electric fridge; we love it.

Have you tested it yet? Are the vent holes adequate for the fridge to reject its condenser heat when drawer is closed? Any issue with heat build-up beneath the stove there?

jkjenn

Excellent work!

Sharon_is_SAM

Well done!  The length of the provided area really dictates what you can put in there.

Michigan_Mike

Looks great!   Will you be boondocking a lot?  And if so you obviously have a solar setup.   I'm guessing with a couple of 6-volt batteries you should be in good shape.  What do the refrigerators cost?

Thanks for sharing!  

4ncar

Fantastic! The finished product looks awesome! I ordered and received my Indel B 41 yesterrday(ordered it days prior). My plan is to use both. @Michigan_Mike mine cost $550.00.

Tabaz

The photos of the finished product are fantastic, but would love to see some taken during the whole installation process.  Please post if you have them.

ericnliz

@GeoMars, Awesome install. Very nicely done.

Michigan_Mike

4ncar said:

Fantastic! The finished product looks awesome! I ordered and received my Indel B 41 yesterrday(ordered it days prior). My plan is to use both. @Michigan_Mike mine cost $550.00.

Just a heads up that I sent this modification on to the factory as I'm sure they will be interested in seeing it.  This frig unit aligns with the T@B 400 setup and since no changes are necessary in the production of the trailer it would be beneficial and doable.  

4ncar

@Michigan_Mike Indel B makes front load units as well, which may be better suited for “factory installed” applications. I, for one still like my 3 way for ease of access. I myself wouldn’t necessarily like to have to “root to the bottom” eavry time I wanted a “chilly!” I am using my Indel B as an auxiliary cooler/backup.

GeoMars

Thanks for all the comments. Consolidating the answers in this reply:
(1) Regarding testing for ventilation: I haven't tested for more than a few minutes, and we've been having cold weather since I finished, so it wouldn't be much of a test. Will report back after the weather warms up. I did leave considerable vent openings in the back and right side of the sliding drawer, and I didn't put any foam on the right half of the front panel (the side where the fridge vents are); those areas are all open to the top and side near the outside vents. I don't expect ventilation to be a problem, because the new fridge uses so much less power than the old one (and therefore will put out less heat), but the back-up plan is to add a small computer cooling fan with thermostat to the vent (quite inexpensive and low power, and would only run intermittently). But I'm hoping this isn't necessary.
(2) We will be using this almost entirely for boondocking. We have two 100ah AGM batteries, a trimetric battery monitor, and charge controller installed. A 200w semi flexible solar panel is scheduled to be delivered next week. 
(3) Fridge cost $712 + tax from Fisheries Supply, but they now list as out of stock. Yes, Indel B also makes front loading units which have separate compressor units and cost considerably more.
(4) More photos: unfortunately I didn't take any photos until I was done.
(5) Regarding factory installation: This would save people a lot of time measuring in 3 dimensions and trying to make everything fit within tight tolerances.

4ncar

@GeoMars regarding install pics...take it a part & redo it!!

GeoMars

Hahaha. Instead of taking it all apart, how about some photos with the drawer pulled out?

This one is the view from the upper T@B vent, showing the 3 sliders under the drawer, the vent in the back of the sliding drawer (lower left in photo), and the flexible conduit with AC and DC power cords. The front of the trailer is toward the right.

This photo is from the lower T@B vent, showing the drawer slides and showing how the fridge vent lines up with the opening in the drawer back for ventilation.


This photo was taken through the T@B door with the sliding drawer open. The opening on the right is to allow access to the power plugs, fuse, and switch that selects the threshold voltage at which the fridge turns off to save the battery. (By the way, I think that all 3 voltage options—9.6v, 10.1v, and 11.1v—are too low to protect a 12v battery adequately, so I'll have to pay attention to the battery meter.) The power cords that came with the fridge stuck out too far, so I had to replace them with lower profile right-angle plugs. 

The opening at the left is for the fridge's front vent (which also vents upward).


Much of the difficulty in fitting the fridge was because the published dimensions didn't include its handles. I assumed that by not using the handles I would have an extra inch or so on each side. When the fridge arrived, I was unpleasantly surprised to see that this wasn't the case, so every 1/8" became important.

4ncar

Again...well done!

Tabaz

This really is an amazing design.  The close tolerances must have caused a few sleepless nights.  Take a well-deserved bow.  What will you do now for an encore?

irvingj

The reason I asked about ventilation (and you may be perfectly OK with what you have):

The amount of electricity consumed is not a measure of how much heat needs to be rejected, but rather the efficiency of refrigerator compressor itself.

I spent 12 years in HVAC, specializing in ice machines-- you know, those little-appreciated devices (until they quit, ha-ha) that sit under bars to make the ice that barkeeps tend to throw away -- first to "cool down" the glass-a quick swirl-- then re-fill with MORE ice... well, you get the picture.

The heat rejected is simply a matter of how much heat is removed from the enclosed space. Newer fridges are far more efficient than older ones, and the new generation of 12V compressors-- piston, scroll (centrifugal), and swing-arm, have been designed with that specifically in mind. And compared to conventional electric motor-driven piston compressors, they've been hugely successful in that regard.

Though they use much less electricity to do their job, they still have to remove X amount of heat from the "box"; that heat has to go somewhere.

I can't tell you how many times I've had to re-engineer airflows for under-the-bar ice makers to get them to be able to do their job!

I hope your beautiful installation works well, but my suspicion (and my recommendation) is to do what you've considered: a small computer-type muffin fan to get that hot air out.

But wait till it gets warm, and let us know how it works. After having a 2-way fridge, (and we have solar & batteries to back it up, which helps tremendously), I don't think I'd ever go back to a 3-way.

GeoMars

irvingj, thanks for your useful information. Will update about power use this spring.

burthardin

GeoMars said:

irvingj, thanks for your useful information. Will update about power use this spring.

GeoMars; Found your post after I purchased my indel b tb51a.  I really like the look of your design, so construction is underway. I'm currently waiting on parts (KV 8505 sliders) to finish. I think I can install the sliders (2) in the vertical orientation and get everything to fit. (My typical, but not necessarily advisable, build/design style of construction.)

I'm curious if you've had a chance to evaluate the indel b's power usage and if you've encountered any other issues running the fridge in the cabinet space? Have you had a chance to test it? Have you installed a fan(s)? 

I'm going to wait and see for myself if I have any problem with heat exchange in the cabinet, but if I do and installing muffin fans, as irvingj suggested, aren't sufficient, I may consider cutting an opening in the cabinet face-plate (about the same size as the indel b's vent dimensions) and trimming the opening with black tinted window screen, or some similar material. 

JonW

I have an Indel B TB41 fridge (not quite as tall as yours) and plan on replacing the NorCold with it, so thanks for documenting how you did yours. 

My only question is how do you control which plug the fridge gets it's power from if (for instance) you're plugged into shore power.  Did you add a switch somewhere so you can easily disconnect the 12v circuit?

Thanks in advance...

GeoMars

Following up on the comments of irvingj and now replying to burthardin:
I finally made some measurements to see if operating the new efficient fridge would cause the modified fridge compartment to get too hot. The summary results are that (a) the new fridge worked extremely efficiently in its compartment (when the outside temperature was 61°), and (b) the fridge is so efficient (and daytime temperatures so variable inside and outside of the T@B that I couldn't detect an elevated temperature in the compartment relative to the (changing) temperatures. 

The details are: The T@B was oriented with the front (kitchen end) pointing North and the back (where solar goes) facing South. When I started making temperature measurements, the outside temperature was 61°. I turned on the fridge (thermostat set to 34°F and MAX mode rather than ECO mode). I then walked to the house to get my IR thermometer and returned perhaps 10 minutes later to find the inside of the fridge had cooled to 38°, and the compartment temperature was 59°. In the kitchen area of the T@B, temperatures were ~63° at knee level and 70° on the ceiling. Within about a half hour the fridge reached the 34° thermostat setting, and stopped cooling. I had expected it to take several hours for the fridge to cool, which would have given me more time to make more temperature measurements, so in order to continue making measurements, I turned the fridge thermostat colder than I would ever use it (down to 0°F). After perhaps 10 minutes, the fridge cooled to 23°, and the temperature in the fridge compartment increased to 63°. This made me think the fridge had heated the compartment by 4° until I measured the temperature in the T@B, which had also increased by 4° (to 67°), although the ceiling was now 80°-90°.

So my tentative conclusions are:
(1) The sun heated up the T@B by about 4° both inside and outside the fridge compartment, but the fridge compartment was cooler than elsewhere inside the T@B during this time (presumably because of the vents and being on the north side).
(2) Next test will be to check power use; just mounted solar panel on roof today. Measuring daily power use will have its own complications because it depends on how many hours per day the fridge will have to run.

GeoMars

Reply to JonW—
If the fridge is connected to both kinds of power, it automatically gives priority to AC. So no switch is necessary unless you want it to use DC when plugged in to both.

JonW

GeoMars said:

Reply to JonW—
If the fridge is connected to both kinds of power, it automatically gives priority to AC. So no switch is necessary unless you want it to use DC when plugged in to both.

Didn’t know that- thanks...

GeoMars

Update regarding air circulation—for burthardin and anyone else following this thread. This fridge has 2 vents. In the orientation in my photos (hinge on right side), air gets blown out the front vent and gets sucked in the back. So today I wedged some foam in the fridge drawer to (a) completely block the top back (above the fridge vent) and (b) leavie a gap in the top front. Now the fridge's internal fan will take air in from the bottom of the fridge compartment and blow the warm air to the top of the compartment.

The next option—before installing a separate fan—would be to place some additional partitions around the fridge drawer so that air is drawn entirely in from the lower T@B vent to the back inlet vent on the fridge, and then have the fridge's fan direct air to the upper T@B vent.

I just finished installing the solar today and will do a power use test in a few weeks.

GeoMars

It took awhile to do a multi-day test of power requirements, but we just returned from 4 days boondocking in southern Utah. Temperatures outside were mid 60s to 71° during the day and 40s at night, and fridge was set to 39°. The weather wasn't hot enough to be a demanding test of power consumption, but our two 100aH batteries never became depleted by more than 5-6%. (This happened over each night, when the panels weren't generating power but we were running the fridge, water pump, lights, TV, and stereo.)

During the day, the panels put out enough power to run the fridge and charge the batteries simultaneously. By mid-morning (before the panels had enough sunlight to put out full power), batteries were 97-99% charged, and the charge controller was only topping them off. So my conclusions for this test are that:
(1) for these weather conditions, 200aH of batteries was more than 15 times what we needed (to keep a reserve of 50% state of charge).
(2) 200 watts of solar panels provided substantially more electricity than we needed.

Of course, multiple days of cloudy weather would have required more batteries, and hotter weather would have required more solar power for the fridge, but for these conditions and with the efficient fridge we had way more electricity than we needed.

irvingj

Thanks for the follow-up! In our T@B replacement (2015 RT SS Agile on a short Sprinter chassis), our experiences have been very similar, though we do have more solar (300W) and more battery (4 ea. 190-ah). We don't usually stay in one spot more than a few days, but we've never had to plug in and the fridge is great. And ditto on the re-charge: if it's sunny, batteries seem to get back up to snuff by 10-11AM. Love it. I'm really convinced that these efficient 12VDC fridges are the way to go.

gulfarea

GeoMars that is great! I have bought 2 Tabs new , first CS with 12 volt-120Ac & loved the fridge. I now have  2019 with the 3-way and hate it! Where did you get the nice wood for the front? Thanks so much Art

GeoMars

The wood is baltic birch plywood. I bought it from Jackel Enterprises in Watsonville, CA (less than an hour drive).

gulfarea

Thanks GeoMars  Art

Tundra57

When I was looking for a camper I saw a 400 boondock with the small 2way fridge under the sink. When I was ordering my tab 400 I saw the option for a 3way fridge. I didn't know that would replace the wardrobe with a larger fridge moved from under the sink. I do miss the hanging area. But I camp with a loaners on wheels group and we make food to share so I make my stuff before I go and put it in the fridge. I prefer being able to open and slide stuff out as I need it. The freezer is just big enough to hold meat for my dog and frozen vegan stuff for me. It seems to work fine on gas if there is no ac power and fine when driving on 12v. I have a small Honda generator which will run the ac and fridge together if I need to when boondocking.

I do really miss the hanging wardrobe, although I mostly wear t-shirts and jeans with the occasional dress or skirt. So the drawers work well. I am still trying to work out how to get hanging storage. There are hooks in the bathroom behind the curtain for coats. I did think of trying to section a narrow space off, but I don't see how it might work yet and there is the moisture issue from the shower. Any ideas in this area?

T_BDancing

@GeoMars, really admire your great mod here. I am trying to replace my fridge as well. How do you do the DC connection? Do you plug it into the socket under the Jensen radio? Thanks.