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Old 05-17-2023, 02:19 PM   #1
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Default fridge level calculation

I know that this has been discussed a lot on this forum, so I am only asking this of the engineers here to check my math:

If a 3-way fridge can be up to 3-degrees out of level side to side (front to back of the van) and up to 6-degrees front to back (side to side of the van). Is the calculation of the difference of height in inches of the front and back of the van and of each side as follows?

front to back: sin(3 degrees) x (length in feet x 12)
side to side: sin(6 degrees) x (width in feet x 12)

For my 1999 Roadtrek 170 (18.1' x 6.8', though this includes the continental kit) this would be 11.37 inches front to back and 8.53 inches side to side. Apart from questions on whether 3 and 6 degrees off-level is really OK or not and other related matters -- is my math right here?
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Old 05-17-2023, 03:28 PM   #2
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I haven't put that much thought into it.


I read that the "tolerance" is about equal to a passengers comfort in the van.


I use an iPhone app which uses the entered wheelbase to tell me which corner(s) need to come up to find level.
( there's a couple times it's been easier to scrape out a couple of inches of dirt at 1 corner)
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Old 05-17-2023, 04:33 PM   #3
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I haven't put that much thought into it.

I read that the "tolerance" is about equal to a passengers comfort in the van.

I use an iPhone app which uses the entered wheelbase to tell me which corner(s) need to come up to find level.
( there's a couple times it's been easier to scrape out a couple of inches of dirt at 1 corner)
Which iPhone app would that be? Thanks!
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Old 05-17-2023, 04:50 PM   #4
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Calculation sems OK. https://byjus.com/maths/sin-cos-tan-values/ As mentioned above this is Android app for calculating necessary lift per wheel to level a camper, motorhome or trailer. https://play.google.com/store/apps/d...hl=en_US&gl=US
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Old 05-18-2023, 12:23 AM   #5
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I read that the "tolerance" is about equal to a passengers comfort in the van.
I use an iPhone app which uses the entered wheelbase to tell me which corner(s) need to come up to find level.
But if my math is OK, and the front of even a 17 foot van could be almost a foot higher than the back and the fridge would still be considered "level" then that would be easy to see just by looking, wouldn't it? And, I expect that much incline wouldn't be very comfortable for walking around in the van at all!
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Old 05-18-2023, 01:53 AM   #6
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Your math is engineer verified! Fun fact, the sine of a small angle (in radians) is equal to the angle (or close enough for an engineer). 3/57x18x12=11.4
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Old 05-18-2023, 02:15 AM   #7
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I remember have an old time propane refrigerator that couldn't care less what the manual or the math said. It either decided to work or it didn't and I don't recall it being very happy with a 1 foot slope. Maybe they make newer ones better now.
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Old 05-18-2023, 02:59 AM   #8
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Which iPhone app would that be? Thanks!

The iPhone app is RVC lite ( the free version, which has ads at the bottom of the screen).


When you enter vehicle info enter the wheel base and width ( I don;t enter my vin or anything like that)


the leveler is under the Menu ( "hamburger") top left corner


I tried to add a pic but I have a devil of a time on this website
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Old 05-18-2023, 02:54 PM   #9
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I remember have an old time propane refrigerator that couldn't care less what the manual or the math said. It either decided to work or it didn't and I don't recall it being very happy with a 1 foot slope. Maybe they make newer ones better now.
It is difficult to know how reliable that 3 degrees number really is. I was just surprised that 3 degrees of slope means almost a foot difference in height from the front to the back of the van.

Anyway, from what I read the problem in this case is simple enough - it is just heat. If the fridge is too far out of level, the fluids in the cooling unit do not flow properly and so the unit gets too hot and this causes further problems. There is a device that is supposed to prevent this possibility by turning off the heating element if it gets too hot. The fridge will stop cooling, of course, but will not be damaged.
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Old 05-18-2023, 03:48 PM   #10
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It is difficult to know how reliable that 3 degrees number really is. I was just surprised that 3 degrees of slope means almost a foot difference in height from the front to the back of the van.

Anyway, from what I read the problem in this case is simple enough - it is just heat. If the fridge is too far out of level, the fluids in the cooling unit do not flow properly and so the unit gets too hot and this causes further problems. There is a device that is supposed to prevent this possibility by turning off the heating element if it gets too hot. The fridge will stop cooling, of course, but will not be damaged.
A key reason for vague off level numbers is that marketing is pushing to higher numbers and actual failure data is very variable. I think high variability is a result of cumulative type of failure. Failure is a function of duration of off the level condition, angle of being off the level, and ambient temperature. All of these factors will cause high temperature condition and accumulative wrong chemistry distribution.

I think high operating temperature sensor and control is a good idea.

I had a few absorption refrigerators and never had issue but I levelled RV as much I could.
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Old 05-21-2023, 06:44 PM   #11
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Originally Posted by RT-NY View Post
I know that this has been discussed a lot on this forum, so I am only asking this of the engineers here to check my math:

If a 3-way fridge can be up to 3-degrees out of level side to side (front to back of the van) and up to 6-degrees front to back (side to side of the van). Is the calculation of the difference of height in inches of the front and back of the van and of each side as follows?

front to back: sin(3 degrees) x (length in feet x 12)
side to side: sin(6 degrees) x (width in feet x 12)

For my 1999 Roadtrek 170 (18.1' x 6.8', though this includes the continental kit) this would be 11.37 inches front to back and 8.53 inches side to side. Apart from questions on whether 3 and 6 degrees off-level is really OK or not and other related matters -- is my math right here?
I would never go more than 2 degrees in either direction. I have a fair amount of experience with leveling refrigerators having camped about 150 nights in my sprinter van over the past few years. I use a free app on my iPhone called protractor 360. I lay the phone on the counter top and use that to level my sprinter with blocks. I find that if it's more than 2 degrees, it does not cool as well. I have read your quotes on the degrees, and it just does not work for me.
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Old 05-21-2023, 10:17 PM   #12
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I would never go more than 2 degrees in either direction. I have a fair amount of experience with leveling refrigerators having camped about 150 nights in my sprinter van over the past few years. I use a free app on my iPhone called protractor 360. I lay the phone on the counter top and use that to level my sprinter with blocks. I find that if it's more than 2 degrees, it does not cool as well. I have read your quotes on the degrees, and it just does not work for me.
For some reason my new Dometic RM2554 (2020) is more sensitive to off-level than the original 2006 unit. New unit made in China, old one in Sweden as I recall.
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Old 05-22-2023, 01:02 AM   #13
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Why not get a round bubble gage. There is even one that is marked in degrees of tilt. Cost less than ten bucks. Put it in bottom of fridge and you are done
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Old 05-22-2023, 10:42 AM   #14
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The app I use on my iPhone is called CamperSet - found here: https://apps.apple.com/us/app/camperset/id309010388

I did pay 4.99 for it but it works perfectly - tells me how many inches need to be added for each wheel. People are always amazed when they see me use it.
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Old 05-22-2023, 12:43 PM   #15
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Ex-Refrigeration tech...I find it comical how difficult many make this relaxing lifestyle. I carry a $5 plastic level. It needs to be at least 1/2 bubble in both directions. Enough said
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Old 05-22-2023, 01:40 PM   #16
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Ex-Refrigeration tech...I find it comical how difficult many make this relaxing lifestyle. I carry a $5 plastic level. It needs to be at least 1/2 bubble in both directions. Enough said
What you think of as "difficult," others think of as interesting and fun (and relaxing!). And there is no need for the sarcastic/negative tone.
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Old 05-24-2023, 02:38 PM   #17
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Originally Posted by RT-NY View Post
I know that this has been discussed a lot on this forum, so I am only asking this of the engineers here to check my math:

If a 3-way fridge can be up to 3-degrees out of level side to side (front to back of the van) and up to 6-degrees front to back (side to side of the van). Is the calculation of the difference of height in inches of the front and back of the van and of each side as follows?

front to back: sin(3 degrees) x (length in feet x 12)
side to side: sin(6 degrees) x (width in feet x 12)

For my 1999 Roadtrek 170 (18.1' x 6.8', though this includes the continental kit) this would be 11.37 inches front to back and 8.53 inches side to side. Apart from questions on whether 3 and 6 degrees off-level is really OK or not and other related matters -- is my math right here?
LOL I'm not sure how many degrees off, get a bubble level...ex refrig tech
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Old 05-24-2023, 05:27 PM   #18
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LOL I'm not sure how many degrees off, get a bubble level...ex refrig tech
I am always interested to know in detail how the machines I rely on work and what their tolerances are. Rules of thumb like "half a bubble" are fine, as far as it goes, but I like to know more than that. It's OK if you are not interested in such things, but then why respond at all?
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Old 05-24-2023, 06:19 PM   #19
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Originally Posted by RT-NY View Post
I am always interested to know in detail how the machines I rely on work and what their tolerances are. Rules of thumb like "half a bubble" are fine, as far as it goes, but I like to know more than that. It's OK if you are not interested in such things, but then why respond at all?
Good point, thank you.
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Old 05-24-2023, 06:35 PM   #20
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I am always interested to know in detail how the machines I rely on work and what their tolerances are. Rules of thumb like "half a bubble" are fine, as far as it goes, but I like to know more than that. It's OK if you are not interested in such things, but then why respond at all?
You must have fun when you use a formula with the symbol Pi.
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