Upgrade from Norcold to Dometic CR-1110 E/F-S (compressor fridge)

[rickst29]

Completed and taken on its first outing. Attached photos are from before my addition of some "plywood edging veneer" to make the verical sides more pretty, and small pieces of wood to seal up underneath and above (under the TM stereo trim fascia).

The Fridge: This is a high-end fridge, intended for use in yachts. Cost $850 plus shipping and local tax. I re-purposed into service for my TM "land yacht", because the original Norcold could not maintain a temperature differential above about 35F. I'm pleased, except that it does not have digital controls and a PT100 thermocouple - just a typically "dial" adjuster, and (I assume) a fluid-filled coil to activate/deactivate power to the compressor. It is 3.8 cubic feet, compared to Norcold 2.7 - a noticably larger interior, and it gets cold FAST.

Since it is adjacent to a stainless steel sink, the stainless finish is the right choice for the door and door frame - black would not look as good. It uses a 12 volt compressor (Danfoss BD35F), and handled this 90 degree afternoon with ease. It automatically switches to 120V when 120V is available, using an internal power converter to drive the compressor, interior LED light (bright blue), and status LEDs (green versus blinking red with 1-5 blinks representing different kinds of problems). Here's a link to the "glossy" promotional sheet. The best "Norcold Replacement" fit occurs with the biggest model, the CR-1110. (PDF) http://www.dometic.com/084ca990-3e16...255ea796.fodoc

The good news: Dometic CR-1110 E/F-S is an exact fit, after you use a plane to remove 2-3mm from the left side TM trim board. (Took about 10 minutes.) If you don't take too much, then this also provides a very sold anchor for Fridge - flange attachment isn't needed to hold the fridge in place. Per the Pic of Interior, with door open, the insulation panels (black) fit the width of the TM flange frame very tight, depending on the care you take cutting the left side back (with a plane). In my install, wood "flange pieces" are necessary only for air seal and appearance - not to hold the fridge in place. Both refrigerators (the old Norcold and the new CR) can be carried (or dragged on a carpet scrap) across the floor to the TM door, and they fit through that door without removing it.

The bad news: You will have to throw away the supplied CR flange, because even the "space saver flange" makes the front to large for the TM opening. (Don't buy it.) You don't need it to hold the fridge in place, although the Fridge does have pre-drilled screw holes for stabilizer screws at the upper left and right- exactly like the ones provided in modern Dishwashers. (And, just like the dishwasher stabilizer holes, there's a plastic cover to remove and press back in to hide the screw and prevent air leakage.)

The biggest amount of time and effort, by far, was about 1 hour to remove/rebuild the propane tubing, and I hour of shopping for propane-related stuff (new flare nuts, and a flare union for 3/8 pipe, and a 3/8 pipe flare tool).

When you return from shopping, pull the 12V refrigerator fuse from the distribution panel. (And of course, disconnect the TM 120VAC plug from any power source.) Then open the lower panel, and cut the the TM propane supply tubing (3/8" copper) 1-2" from the flare nut where it enters the fridge (in the back, reachable from the lower air vent opening). Pull all electrical connectors from the connection panel to the left of the propane connection. Next, underneath the trailer, cut the propane pip "T" on all sides - fairly close to the nuts (maybe 1"), but not so close as to create bends or flattening in the loose pipe ends ends. The end from the supply line, and the end towards the propane-fired water heater, BOTH need to be perfectly round (so that they can be flared properly).

Now go inside the TM. Remove the Norcold mounting flange (around the Norcold door) and pull the fridge forwards, exposing the 3/8 tubing into the floor. Cut again, so that the long, twisty, portion of tubing can be pulled free into the Norcold-vacated space, while you push the short portion down through the floor opening.

Now go back underneath Trailer. Straighten some of the "extra length" which TM provided in the propane line underneath the Trailer (thanks for that extra length, TM!), so that the two ends of remaining pipe (from the Cross adapter, and to the water heater) can reach to your new union flare fitting (exactly). Put the nuts onto the pipe ends first, then flare the two ends (with GREAT CARE), and then assemble/tighten the at both ends of the union. Turn on the gas supply at the tanks to test for bubbles at the new joints, using dish soap.

After this, it's back up to remove the Norcold (about 10 minutes of wiggling, lifting through the TM door, etc.). Next, remove the flange from the new refrigerator, and then lift it into the TM. Next, use a block plane to trim 2-3mm from the sink-side vertical wood piece, on which the Norcold flange was attached. On the other side, relocate the "sticks to far out" 120V Romex cable so that it is behind (rather than alongside) the TM front trim board. It is convenient to plug in the Dometic 120V cord (at the plug end, not the fridge end), now - before you close up most of the front opening and can't see the holes in the 120V socket. The Fridge should slide in firmly, but without tearing up insulation panels on the sides. (Tilting and then leveling, front to back, can help with this "slide-in" process.) Use plastic or spar-varnished pieces of wood to fill the air gaps under the front of the fridge: If wood, as I used, be sure to varnish all 4 sides, because you will get them wet if you ever open the door and allow "dribbling" of leaky fridge contents to occur.

Plug in the Dometic 120V cord, and turn it on. Be amazed at how fast it gets cold. Chill a beer in the freezer, and measure the "flange-replacement" wood strip sizes. Connect the 12V (be absolutely sure of polarity), install your trim, and varnish the strips.

[ShrimpBurrito]

This is very interesting. I am anxious to hear first-hand reports of its operation, particularly power consumption. If you find your batteries last a reasonable time -- say a week -- with your solar setup, then that would be very attractive to me. While I love that the propane fridge basically sips fuel and consumes virtually no power, I too have had problems with its slightly anemic cooling capacity.

Dave

[Bill]

Like Dave, I'm finding this very interesting on a couple levels. First, we have not found the TM's OEM fridge to be especially lacking in cooling capacity, though it has pretty poor temperature control. (I keep thinking I should do something about that, but haven't made the mods suggested on this board.) As we crossed the country on our recent trip, we kept the thing switched to the AC power setting, at a dial setting of "3", so it was actively cooling whenever AC power was available. Late afternoon, and all night. Then we simply turned it off as we drove trhough the day. This approach worked pretty well - we didn't freeze as much lettuce as we used to. It maintained temperature pretty well all day - part of that is from fixing the freezer door spring, I think. I would love to have more capacity, though - that 2.4 cu ft isn't much.

The second issue is that Danfoss compressor. We have a 10-year-old Engel 45-quart chest-style frig/freezer (which uses the Sawafuji "swing motor", a slightly different compressor than the Danfoss). We carry it on the back seat of the Explorer, and in the first five years, we used it a lot, setting the temperature to the lowest it would go so we could lug Maine seafood to Arizona, and Arizona tamales and peppers to Maine. Then about 5 years ago, we started using it as an extra freezer in our home, so it has been running 24/7 for 5 years! It seems absolutely bullet-proof. I would offer one caution, though. One night at Chiricahua National Momument, I left it plugged into the cig lighter in the Explorer. We set up camp at 3PM, and next morning at 8AM, the Explorer battery was dead. So although it does not consume a lot of power, 17 hours of freezer operation was too much. Most likely, solar would not have solved the problem, since the unsupported drain was at night. I would expect the bigger refrig that Rick installed to have a somewhat higher drain, although running it as a refrig instead of pure freezer would help a lot.

At any rate, it makes me wonder if TM could be persuaded to build and deliver a trailer with no refrig installed. Just cap off the propane and electric lines. I don't think they would install this new Dometic for you, but your own installation would be easier if you didn't have to deal with the Norcold. And maybe save a few bucks.

Just a thought. My points, I guess, are that the Danfoss reciprocating compressor, as well as the Sawafuji unit, is great - no one should be afraid of it. And although its 12-volt power consumption is lower than the Norcold, it will still eat your batteries if you don't have some way to keep them up.

Bill

[rickst29]

Originally Posted by ShrimpBurrito

This is very interesting. I am anxious to hear first-hand reports of its operation, particularly power consumption. If you find your batteries last a reasonable time -- say a week -- with your solar setup, then that would be very attractive to me. While I love that the propane fridge basically sips fuel and consumes virtually no power, I too have had problems with its slightly anemic cooling capacity.
Dave

I'm sorry , but we don't boondock for such extended times, and I can't directly report on battery survival. (After 2 nights max, we either come home or schedule the next night at an RV place with electric and sewer connections.) I wil report on battery voltage in the AM, but this is with both Dometic and my CPAP drawing through the night, and with other "phantom loads" also present (primarily the Stereo and gas detector).

My Solar setup seems to have plenty of extra power- my CPAP machine uses about 50 watts through the night (7 hours), but the PWM finds the batteries to be "fully" charged by Noon, or even earlier. (Fridge running on gas under those circumstances). That's daylight time, with more than half the day left unused. My solar is 200W nominal, I'll SWAG at 140W max after PWM losses - the wiring losses are insignificant, compared to the losses in my PWM controller.

Per another thread, and the Danfoss spec sheet, I'll guess the continuous power consumption of the new Fridge at 5-6 amps while running continuously. Pure SWAG, of course, and I'm not putting a quality power meter to isolate the fridge consumption from other loads. (My lights are all LED, but "phantom loads" are pretty high. Stereo and Gas Detector are probably the biggest "phantom" loads.) If these guesses are reasonably close, I can also "make up" for nearly all the power consumption of the Fridge by switching from PWM to MPPT.

I will post my actual results after seeing what happens in late July and early August, our hottest weather times.

[rickst29]

Originally Posted by Bill

Like Dave, I'm finding this very interesting on a couple levels. First, we have not found the TM's OEM fridge to be especially lacking in cooling capacity, though it has pretty poor temperature control. (I keep thinking I should do something about that, but haven't made the mods suggested on this board.) As we crossed the country on our recent trip, we kept the thing switched to the AC power setting, at a dial setting of "3", so it was actively cooling whenever AC power was available. Late afternoon, and all night. Then we simply turned it off as we drove through the day. This approach worked pretty well - we didn't freeze as much lettuce as we used to. It maintained temperature pretty well all day - part of that is from fixing the freezer door spring, I think. I would love to have more capacity, though - that 2.4 cu ft isn't much.

Last summer, our Norcold was allowing interior temps to reach nearly 60F in 95-100F weather conditions - even with my PID-based electronic regulation making sure that the Norcold heater ran 100% of the time. Even in camp, with the upper vent available to exhaust heat. And I have a large (140mm) auxiliary fan to pull air out through upper vent - also PID controlled, and turning on when temps in the of heat exchange reach just 85F. Probably, for some unknown reason, the ability for fluid to flow properly and/or exchange heat has become compromised within my Norcold Fridge, It did work A LOT BETTER in years previous to last summer.

Originally Posted by Bill

The second issue is that Danfoss compressor. We have a 10-year-old Engel 45-quart chest-style frig/freezer (which uses the Sawafuji "swing motor", a slightly different compressor than the Danfoss). We carry it on the back seat of the Explorer, and in the first five years, we used it a lot, setting the temperature to the lowest it would go so we could lug Maine seafood to Arizona, and Arizona tamales and peppers to Maine. Then about 5 years ago, we started using it as an extra freezer in our home, so it has been running 24/7 for 5 years! It seems absolutely bullet-proof. I would offer one caution, though. One night at Chiricahua National Momument, I left it plugged into the cig lighter in the Explorer. We set up camp at 3PM, and next morning at 8AM, the Explorer battery was dead. So although it does not consume a lot of power, 17 hours of freezer operation was too much. Most likely, solar would not have solved the problem, since the unsupported drain was at night. I would expect the bigger refrig that Rick installed to have a somewhat higher drain, although running it as a refrig instead of pure freezer would help a lot.

At any rate, it makes me wonder if TM could be persuaded to deliver a trailer with no refrig. Just cap off the propane and electric lines. I don't think they would install this new Dometic for you, but your own installation would be easier if you didn't have to deal with the Norcold.
Bill

I agree about the value of TM delivering a "fridge-not-included, no fridge propane connection" option for someone who knows that they will install an electric-only, compressor-based Fridge after delivery. From the "Cross" connector near the tanks, they could pull the WH/Fridge supply line all the way to the Water Heater, with no "T" installed underneath at all. Less work for them, far less work (on my back) for me - and no chance of seeing bubbles in the 'dish-soap' test of the replacement Union joints. (I was, thankfully, somewhat "skilled" in my flare assembly, and didn't have a leak. That part of the job just consumed most of the time, and consumed substantial muscle power.)

If the Engel cooler and Dometic fridge are "tied" for power consumption (which I think to be unlikely, due to your "freezer temp" usage - and also because the insulation probably isn't as good) - 17 hrs * 6 Amps ~ 100 AH. My Solar 'available power' is, unfortunately, currently less than that - probably less than 70 AH. So, running flat-out through the night, I'd need the MPPT upgrade (or a panel upgrade) AND a 3rd battery, in order keep up with demand through multiple nights. But I think that there's no way it would need to run flat-out through the night to hold fridge temps - Desert ambient temps gets quite cool at night. A daily range of from 95+ down to low 60s common around here.

Our readers can keep in mind that the SUV battery is a starting battery: A pair of deep cycle RV batteries, even el-cheapo Walmarts at 80 AH each, could easily handle the 30 AH deficit for a day. (Although they would be well under 50% red-line if asked for 100AH overnight, with no Solar charge capability taking part of the load during the last hours of the day, and the early AM.)

If my fridge ever DOES need to run continuously, at high amperage, through long nights - then I'll need to do the MPPT upgrade and add a 3rd battery. But I think that the Dometic won't need to run that hard. Just SWAG, of course.

BTW, the Dometic 1110 fridge door has "active" clamps for shutting both the top and bottom of the door, helping to maintain a very effective seal. And the speed of cool-down, with 120V mains available, was amazing -- I no longer have a need to open up and pre-cool overnight.

[rickst29]

They gave me an old manual. The 5.9A figure is for the previous generation (CR-80 and CR110), and it shows 5.7 Amps for the small ones. Perhaps the CR-110 and CR-80 previously contained the slightly bigger Danfoss BD-50; but they definitely all use the BD-35F in the current product line. My original SWAG of 65W needs a slight increase, 12.6V * 5.7A = 72 Watts.

- - -
On the other subject: An Australian RV Board has a long thread about "performance problems", in which all issues seem related to an older version of the Thermostat. Dometic/Waeco has upgraded the thermostat section, but that was primarily for operating in lower temperatures. I don't know if the new one prevents the need to "fiddle the dial" between hot days and cold nights, or whether the mechanical dial adjustment is too "finicky" near the desired value. If it isn't a digital thermostat already, then Digital replacement still seems like a good idea.

Unfortunately, my existing PID Controller (the "Norcold fix" device) was built primarily as a PID, and stops (for about 2 seconds) once every 200 seconds, while it does the math. Rapid cycling is harmless for the Norcold AC and DC heater coils, but disasterous for the Compressor. At a cost of $40 shipped, I've bought a non-PID fridge/heat digital thermostat which doesn't have complicated settings for PID control - it simply turns ON when the thermocouple measurement reaches the maximum of the desired range (about 38F), and turns OFF upon reaching the bottom of the desired range (34F).

Per Danfoss controller documentation, the new "thermostat" must not "rapid cycle" the entire unit - it must be installed to provide either zero resistance, or infinite resistance, between the "C" terminal connection (after the speed control resistor, if Dometic installed one) and the "T" terminal. I have no idea of the amperage through the thermostat, but I'll need a separate relay in any case - because the non-PID thermostat "relay terminal" sends full "power" voltage down the connector, and assumes the other side to be 12V Ground. Both assumptions are almost certainly wrong for the "T" and "C" terminal connections. (With an external relay the 12V thermostat output closes the relay - and the "load terminals" simply deliver whatever voltage and current is supplied between the leads.)

I'll try without installing the "replacement" thermostat" components first, and see if the provided mechanical thermostat is accurate enough.

[rickst29]

We headed out to Berline-Icthyosaur State Park for an overnight. In spite of the altitude, it reached about 90F during our travel time and set-up afternoon. The last 15-20 miles are on a dirt road, and I had needed to do some interior clean-up when we arrived. No plugins, but bright sun for the Solar Panels. Upon arrival, the lettuce was frozen (but not the beer). We had been traveling with the supplied thermostat set to "6", and turned it back a bit (towards "5").
The OEM thermostat, following that adjustment, seems to have done a good job... but with no unfrozen lettuce for a further "test", and PID measurements taken only by hand , a couple of times... I can't say exactly how much temperature variance occurred inside the fridge. But it seemed very tight - not reaching above 40F (SWAG) and definitely not freezing the remaining beer within the night.

Very pleased overall. With bright sun for the entire drive to camp (3-1/2 hours), my batteries arrived fully charged, and after the overnight it had fully recovered by some time before 2 PM. Maybe a long time before 2PM, but we were out touring, and didn't see exactly when that occurred. (Night time loads included my CPAP and the Fridge - lights were negligible, because they're LED.) I didn't try to take a current measurement.

[Skyjim73]

Rickst29, you choice of the Dometic CR-1110 has reassured me - I picked it out of a boating supply catalog for fit (though there were Isotherms that were close in size as well), and also knowing that TM is presently dealing with Dometic as a supplier for the 3 way fridges, I might have a better chance of getting the factory to engineer the installation. Dometic would be motivated, I hoped, to provide tech support, and TM would be able to provide an option for their customers who boondock in warm places like the desert southwest, and already plan to have solar and upgraded battery banks. (Also, to be honest, I think it is a very straightforward mod, as long as the customer understands the need for a robust DC system!)

My wife and i actually ran a little experiment last year after 16 years of hating the lousy en-route cooling performance of the absorption fridge in our old rig. Only reservation i had was whether the BD-35F would be noisy enough to bother us at night, so I picked up a little Dometic CDF-11 for our truck, which happens to be the tiniest BD-35F unit I could find. After falling in love with it as an in-cab replacement for regular coolers, we set it up inside out rig during a trip to Death Valley and found that the noise is not an issue for us - so on to trying to order one in a new TM!

I originally had the idea expressed above - maybe I could get TM to build me a unit "less fridge", no propane plumbing but with DC and AC circuits roughed and appropriately fused/breakered. But now my dealer, Custom RV in Ontario, CA, seems to be pretty sure TM will do the whole install. If so, I am probably in your debt, since I'm sure they follow these threads.

I'm already a fan and sold on the TM design for my purposes, though I realize it's not for everybody. But if TM does come through with this customization request, I am going to be thrilled and impressed with their responsiveness to customer input and probably become a hopeless TM promoter!

Will hopefully have our answer next week when we place our order - supposedly we will have the chance to speak to the TM folks in person at the Pomona RV show, where we intend to place the order. Will update!

[funpilot]

I am interested in going down this path as well. I called Dometic and they confirmed that this unit is suitable for RVs. I am attaching the installation manual and brochure on the CR line. I have read on other forums that the CR-1110 cools so fast that you do not have to start it the night before.

[rickst29]

Originally Posted by Skyjim73

Rickst29, you choice of the Dometic CR-1110 has reassured me - I picked it out of a boating supply catalog for fit (though there were Isotherms that were close in size as well), and also knowing that TM is presently dealing with Dometic as a supplier for the 3 way fridges, I might have a better chance of getting the factory to engineer the installation....my dealer, Custom RV in Ontario, CA, seems to be pretty sure TM will do the whole install. If so, I am probably in your debt, since I'm sure they follow these threads.

Hi, Skyjim! TM would have to engineer alternate framing shims for you, and carefully study the entire installation scheme. I will SWAG that effort to be cost-prohibitive to you. (I think that factory pricing for Solar, in comparison to DIY, supports that guess; and the Solar Option also has a much larger market than the Fridge upgrade.)

Their pricing and support for the "simple discount" scenario, in which they run pipe from the Supply/Stove/Water-Heater "T" directly to the Water Heater, is probably best. Per above, they leave out the Fridge Propane "T", but build the refrigerator containment as if it were going to contain a Norcold.... and they DO build the standard vents and install the ventilation fan in the bottom. (That's important!)

They would install the electrical wiring exactly as they do for Norcold, even using the same fuse. (The CR uses much less DC while it runs, but has a large "start-up" current draw. I left the 20A fuse in place to allow for this.)

The only differences between your order and a standard TM would be in the propane supply line (directly to Water Heater), and the Fridge simply left uninstalled. Keep it Simple for them.
- - - -
IMPORTANT 1: Do not assume that TM follows every thread in detail, OR that the particular person they send to Pomona would know about this modification. Instead, print the entire discussion for them.

IMPORTANT 2: Per your signature: Unless the Morningstar is a fancy MPPT, I feel that 2*64W panels is insufficient to both run the Fridge and adequately recharge the batteries in normal summer conditions. My checkout trip was taken mid-summer (long days), cloud-free, and high altitude (7000 ft.). PERFECT for Solar production. Just a few clouds, or a tiny bit of shade (while boodocking), and you could easily find your 12V electrical SOL in the second night.