Working on Dometic 2201 - Fiberglass RV
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Old 04-15-2017, 01:10 PM   #1
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Name: William
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Lakeville, CT
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Working on Dometic 2201

Probably nothing new to see here but I thought I would document the work we are doing on the Dometic 2201 3-way fridge in our 80-something Scamp 16'. We've had it for about six or seven years and the fridge has never been great. We've done small things to get it reasonable like fan on the coils, cleaning out the orifice and burner. Last summer it was particularly bad on LP so with a six month jaunt coming up decided we would try to get it in shape or get a new one. It started right up on LP a week ago and cools to 30 F below ambient. I removed it from the camper and brought it home and on AC cools to 40 below ambient. I tried the "burp" trick and left it upside for awhile and it cooled to 42-43 below ambient on AC. Each time I make a adjustment or modification I plan to run it until it hits equilibrium so I can see if that change made a difference. Meanwhile, I pulled the gas burner and flu apart and cleaned the orifice, burner, flu and baffle. Adjusted the crossover tube that connects the flu and the balanced flu tube. Nothing seemed to out of whack on the LP side but I hear that the system is delicate so a small change can sometimes make big difference. Let's hope.

Plans for the next few days from researching as much as I can:
-Reinstall and try again on LP
-insulate top and sides with foil-lined foam board
-install an interior fan
-make baffles to direct outside air through the upper coils and then out the upper vent
-work on door seal (bottom in particular is quite hard and failed dollar bill test)

Anyone have a source for replacing the door seal? Either a direct fit or some kind of universal. I don't really want to rip it out to match for fear that I might not find anything.
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Old 04-16-2017, 09:54 PM   #2
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Name: William
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I tried removing the freezer door and it settled at about 45 F below ambient. When I put the door back on it went back to about 40 F below ambient. I 3D printed a holder for an interior fan. The part slips on a lantern battery and holds the fan above. There are slits in the sides so the air can travel in and up.
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Old 04-16-2017, 11:32 PM   #3
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As a retired engineer, I have to do a big salute to your diligence at working the issues one by one to fix the problem. Well done!
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Old 04-17-2017, 06:11 AM   #4
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William

I have no experience on the smaller unit in your Scamp but on the Casita forum there's a L O N G thread that's a combination of several on making the larger refrigerator used in the 17' Casitas work better. Here's the thread but you need to be a member to read it.
https://www.casitaforum.com/invboard...ge-run-better/
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The biggest improvement for several/many or most was to separate the heat from the propane flame in the chimney from the lower temperature heat from the refrigeration coils.
this can be accomplished by fabricating a aluminum shield that goes around the burner area extending upward to as near to the vent on the side of the trailer as possible.

Secondly directing airflow through the upper fins instead of around helps too.

Here's a couple of pictures of my vents that solved my problem. With these two modifications it was not necessary to run the exterior fan I installed but the interior one still provided even cooling throughout the inside of the box.
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Old 04-17-2017, 09:27 AM   #5
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Name: William
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Joe, Ah... The baffle making sure air flowed through the coils was already on my list but the vertical separation was not! I'll give that a try.

I do have some interesting results from the interior fan. The deltaT went down 10 F. So instead of 40 below ambient I woke up to 30 below ambient. It must be that the waste heat of the electric motor is greater than the extra heat given up by introducing more air to the cooling fins. Not what I was expecting at all. I removed the fan and could immediately see it start to cool further. deltaT is at 36 F after only an hour.

There is a tremendous amount of evidence that interior fans are working for people. It could be that I have a particularly inefficient fan (thought not particularly warm to the touch) or that there would be more gains if I had "stuff" blocking the interior flow. Not sure. I'll put that on hold until the unit is back in the camper. Today I will concentrate on insulating and ducting the fridge and compartment.
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Old 04-17-2017, 09:28 AM   #6
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Name: William
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Charlie,
As a physics teacher I am obligated to control my experiments at least as well as my students do!

Cheers,

Bill
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Old 04-17-2017, 01:45 PM   #7
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Charlie,
As a physics teacher I am obligated to control my experiments at least as well as my students do!

Cheers,

Bill
Being a physics teacher you might appreciate the graphs one fellow made showing the temperature differences end to end on the exterior fins with different modifications.
An example can be seen in my pictures, originally my separator was held on by a tab around the refrigerant tube. That transferred flame heat to the refrigerant tube
Just mounting it differently and adding the coke can extending it upward helped a lot

Joe
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Old 04-17-2017, 02:57 PM   #8
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Makes sense Joe. I think I have done something similar to you to make sure the heat is not conducted through the shield. I will add a piece to the slot and complete the shield without making contact with the cooling tube.

I am working the door seal with a heat gun. Heating it up, helping it expand and then closing it so it cools in the correct shape. Seem to be making some progress.
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Old 04-24-2017, 03:41 PM   #9
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I have the fridge installed in the camper once again. Have a 12 V 0.63 A fan blowing hard on the upper coils. I insulated the sides and top of the fridge with foil-lined foam board and started in on LP. After 18 hours or so it is only 33 below ambient. Very disappointing. The flu insulation is not as hot running on LP as it is on AC but I cleaned that whole propane system thoroughly. Flame is nice and blue and is steady but maybe not as big as it should be. Time to check the pressure, I suppose? Can anyone think of anything else relating to the propane combustion?
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Old 04-24-2017, 05:29 PM   #10
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William, I feel your frustration. I also read everything I could find on this forum a couple of years ago, and could not significantally improve the cooling of our 13' Scamps Dometic 3 way refrigerator. I finally gave up and installed a 12 volt only danfoss compressor style NovaKool refrigerator along with a single 100 watt Renogy Solar panel connected to our single group 27 battery for about the same cost of a new 2 way absorbtion refrigerator..... the best thing I ever did. We now own a Lil Snoozy that has essentially the same set-up, and we use it mostly boondocking for 4 months at a time in various places around this great country. We have instant cooling as soon as we flip the switch, even here in Phoenix Az in the summer. I really can't see us ever going back to an absorbtion style refrigerator.
Dave & Paula
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Old 04-26-2017, 11:55 AM   #11
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Dave and Paula, thanks for your input. May I ask which model fit well in your 13' Scamp? I will keep working on the Dometic but I'm also considering other options.

Turned the fan off for a day or so and the Dometic 2201 is still 33 F below ambient. That seems like it would be consistent with the flame not being adequate. I plan on researching pressure testing the system.
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Old 04-26-2017, 11:58 AM   #12
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I just had my Dometic 2510 serviced after buying the trailer eight years ago.
They pressure checked and checked for leaks in the propane and then they replaced the regulator at the propane tanks. It wasn't delivering what it should.
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Old 04-26-2017, 02:05 PM   #13
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Joe,

Could you tell me the model number of the Dometic frig that is in your photos?

On the outside of your Casita, would you measure the height from the bottom of the lower panel (intake), to the top of the upper panel (exit), and tell me how many inches that is?

Is your second photo that is showing the top cooling fins, is the camera pretty much straight out from the fins?

Could you tell me or better yet, post a photo of what is directly above the frig on the inside of the Casita. Is it a counter top, closet, or what?

Thanks,
Jim
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Old 04-26-2017, 03:21 PM   #14
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Joe,

Could you tell me the model number of the Dometic frig that is in your photos?

On the outside of your Casita, would you measure the height from the bottom of the lower panel (intake), to the top of the upper panel (exit), and tell me how many inches that is?

Is your second photo that is showing the top cooling fins, is the camera pretty much straight out from the fins?

Could you tell me or better yet, post a photo of what is directly above the frig on the inside of the Casita. Is it a counter top, closet, or what?


Thanks,
Jim
Jim

The refrigerator is a Dometic 2453

Camera was pretty much straight in.

The upper vent opening is right at the bottom of the microwave shelf.
Even though the plastic vent has a larger opening it does not cover ANY of the many rivet holes from the metal vent.

I filled the the 18 as I remember holes with a fiberglass patch then sprayed the area with some enamel paint I had Sherwin Williams mix that is a perfect match. The person I got the idea of updating the vent used snap caps to fill the holes.

I cut roughly 1.5" fiberglass off the bottom side and maybe 1/2" on the top.

The opening from the inside of the lower vent where the grill rests, to the top of the upper where where the grill hits is 38"

Here's a picture through the door showing how little space there is.

The underside of the plywood shelf the microwave sits on is literally right at the vent.
There was no support at the rear of the shelf so it has not been structurally compromised.

anymore questions just ask

Joe
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Old 04-26-2017, 03:39 PM   #15
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Dave and Paula, thanks for your input. May I ask which model fit well in your 13' Scamp? I will keep working on the Dometic but I'm also considering other options.

Turned the fan off for a day or so and the Dometic 2201 is still 33 F below ambient. That seems like it would be consistent with the flame not being adequate. I plan on researching pressure testing the system.
Dave.

Google "making a water column manometer". Simple to make and totally accurate.

The regulator by the tanks is adjustable but not much in the more pressure mode. Turn on several gas appliances when your testing for an accurate reading.
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Old 04-26-2017, 04:37 PM   #16
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Name: RB
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This is funny. I'm doing exactly the same things with exactly the same fridge - an RM2201 in my '92 Casita.

I also get about 40 degrees on 120V and 30 degrees on LPG. Leaving the freezer door off did improve things somewhat.

I'm down to the belief that the biggest problem is keeping heat out of the cold box. I'll be removing the fridge and aggressively insulating all around it. I think this is the major reason why it runs worse on propane than electricity - the propane burner puts off a lot of heat and the insulation on the cold box is pretty thin.
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Old 04-26-2017, 06:16 PM   #17
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[QUOTE=biw314;637097]Dave and Paula, thanks for your input. May I ask which model fit well in your 13' Scamp? I will keep working on the Dometic but I'm also considering other options.

I don't remember the model number, but if you go to their website or google search any danfoss compressor 12 volt refrigerators you can find exterior dimensions that will fit your needs. The NovaKool was what we put in our Scamp 13, and now we have a Truckfridge in our Lil Snoozy. Norco and I believe Dometic all make a danfoss compressor refrigerator. I went with the 12 volt only option on both of ours, as they connect directly to the battery, and if we are on shore power, the battery charger will keep the battery charged up, so why pay extra for a built in 110 volt AC to 12 volt DC converter. Best of luck with your cool project.
Dave & Paula
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Old 04-27-2017, 07:11 AM   #18
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Name: William
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Checked my system for leaks and found one where the line comes into the fridge. Since I've been pulling the fridge in and out I did not do a good job making sure that was sealed. Fixed it and started the fridge. Maybe the leak lowered the pressure enough to reduce the flame enough to... We'll see in a bit.

Am currently working on building a manometer to test the system pressure.
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Old 04-27-2017, 09:12 AM   #19
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Name: William
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Here's my 15 minute manometer! The Tube ID should slip nicely on the end of the stove top valve for easy use. Excited to try it this afternoon.
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Old 04-27-2017, 09:51 AM   #20
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Here's my 15 minute manometer! The Tube ID should slip nicely on the end of the stove top valve for easy use. Excited to try it this afternoon.

The stove top in my Casita has an additional regulator in it to regulate it to a pressure lower then 11 inches as does the furnace and water tank.

In my Casita the refrigerator is the only gas appliance that totally relies on the main regulator making it more sensitive to lower pressure from the main one.

My refrigerator has a test port, see the picture, as do the others.

Joe
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