Fridge affected by elevation?

[RLP]

Do any of you folks know if the performance of a 3 way fridge running on propane is (slightly??, greatly?? moderately??) effected by elevation? Mine seems to cool nicely at 1500 ft but no cooling at 4800 ft. In both locations, freezer freezes great. On 110 volt at both locations everything works fine.

Recently installed this fridge (Dometic RM211) and paid close attention to proper venting of the back coils, incorporating baffles and installing additional vent slightly above top of fridge to exhaust warm air.

It's got me 'baffled' (pun intended).

[Carol H]

Elevation will impact how well propane burns & some gas appliance indicate that 4500 feet is when issues may start but I have been at around 8/9000 and the fridge worked. It did struggle a little though but it was also pretty warm when I was camping there at the time.

A few other things that will impact the how well the fridge cools down are:
Too much stuff in the fridge (very common issue)
Ice build up on the freezer section due to fridge being set to high.
Do you have a little fan inside the fridge to circulate the air - found that helps.
I also used last week-end a small little battery fan in the rear vents and it helped cool the fridge right down even though it was 97 in the shade.

Whats your gas regulator set at?- dont hold me to it but I seem to think it is suppose to be at 11 ".

Here is a link to a how to troubleshoot a regulator.

[RLP]

Thanks Carol. I installed a new regulator and my understanding is they are all set to 11 inches w.c. (water column) which is an industry standard for propane appliances. I will make a simple nanometer and test that at 1500 ft and where I camp at 4800 ft.

Just thought of something - regulator is made (and factory set) in San Marcos Texas which is only a few hundred feet above sea level. Wonder how much it deviates in Kelowna BC (1500 ft)?

I was told that fridges are designed to cool/freeze the freezer first then cool the fridge and also told that they are quite intolerant to gas pressure changes............the operating window is something like 10.6 to 11.4 w.c. So, maybe there is just barely enough pressure to freeze the freezer but nothing left to cool the fridge - hummmmm.

I would love to cram the fridge full but then I would eat to much!! No, I don't cram and try to pack things with spaces between.

No ice build up in freezer.

I have no fans installed inside or out but that is on the to do list.
Thanks.

[Scott H]

Great question! I live at 7000' and most of my summer camping is done higher than that. My RM211 works poorly but i've always attributed it to the fact that it's a 34 year old fridge. Please tell me that all i've got to do do to make it work right is move.

[Carol H]

As I indicated my understanding is that on most RV's the regulators are set at 11 for best performance for all the appliances.

Hummmm..... is your propane tank getting low? or perhaps its just a malfunctioning regulator.

I would be surprised if being at 4800 feet would cause it to not work .... most of Yellowstone for example is much higher than that (actually almost double) and I dont recall anyone saying their fridge would not work...... mine worked not great - right at 40 as long as I didnt open the door in the heat of day. It dropped down lower at night when it was cooler though.

Sorry cant be of more help.

[Carol H]

Scott does it work at your home at 7000'?

[Victor Benz]

One other aspect is the propane source. I am in central Alberta, and the further south one goes, the more butane is allowed in the propane. Butane evaporates at a significantly higher temperature. It's not an issue in warmer climes or lower elevations but was quite an issue for me. I had two 20# bottles on my Fiber Stream, one filled in Alberta and one filled in California. Only the Alberta bottle worked well in Yellowstone in mid-September.

Vic

[Carol H]

Interesting. Who know! As a backpacker I am aware that in cold weather butane stoves dont burn well at all .... perhaps that explains way in the Great White North the mixture of butane in with the propane is less than it is in the south. So I am assuming that the extra butane in with the propane also has an impact on the pressure in the tank at certain elevations??? How does that work?

[RogerDat]

Originally Posted by Carol H

....So I am assuming that the extra butane in with the propane also has an impact on the pressure in the tank at certain elevations??? How does that work?

Regulator should not care, it's just a diaphram and spring that only allows a certain amount of pressure to reach the line.

Pressure is result of liquid "boiling" to a gas, until pressure get high enough to prevent more gas from escaping liquid. If the mix can not convert from liquid to gas fast enough pressure will drop.

Used a large (80,000 btu) propane heater in my garage during the winter, the tank would frost up (conversion from liquid to gas draws heat from tank so it frosts). If I ran heater on high for awhile flame would slowly die because tank could not keep up the pressure. If I used a pair of 100 lb tanks it would not have this problem.

I know that butane camp stoves are not good in cold weather because the butane draws more heat in order to convert to gas so it does not generate enough pressure to maintain the stove flame.

Elavation may not be the key, temp and butane ratio might be. It's generally cooler at higher elevations preventing butane rich mixture to boil fast enough. But rv fridge does not have much of a burner flame so it seems odd that the flame would shrink that much.

[tractors1]

Any yellow residue on the outside of the fridge in the area with the coils? Ammonia systems work differently (absorption) in the two compartments (freezer top and cooling bottom) - bottom depends on a cycle that has some water/hydrogen to cool and not freeze. Might want to have the fridge checked for gas content, the yellow residue would indicate an ammonia leak.

[dylanear]

My Dometic fridge worked great from October to June at 7000ft, but that was on 110V AC. Never tried it on propane up there.

[Jon Vermilye]

My Dometic RM 2510 did fine for a week & 1/2 at Leadville, CO - 10,000' on propane. Of course it didn't have to work all that hard - went down to the mid or low 30°Fs each night! Sure wish it would do as well now that I'm at 800' and hitting 100°F every day.

[Terry G]

I have a place where I take my Casita at about 10,500 feet in Colorado and, like the above post, I've never had a problem with the Dometic refrigerator cooling. Since they talk about the freezer working fine, I believe the problem with OP might be more connected to poor air circulation in the unit. A small battery powered fan (less than $20) might make all the difference.

[Carol H]

Originally Posted by Jon Vermilye

My Dometic RM 2510 did fine for a week & 1/2 at Leadville, CO - 10,000' on propane. Of course it didn't have to work all that hard - went down to the mid or low 30°Fs each night! Sure wish it would do as well now that I'm at 800' and hitting 100°F every day.

Last week I caved in and wrapped my fridge in some reflective foil bubble type wrap. Put new batteries in the little fan in the fridge, added a small fan to the rear outside of the fridge and left the hatch door open during the day - in the high 90's F over the week-end and I didnt have any shade. Fridge never went above 33F. Best its ever done in those conditions..... way better than I had expected.

[Victor Benz]

Originally Posted by RogerDat

Regulator should not care, it's just a diaphram and spring that only allows a certain amount of pressure to reach the line.

Actually, not quite true. The pressure regulator is a differential pressure device, providing a supply pressure of 11 inches water column above the ambient pressure at elevation.

The difference in atmospheric pressure between sea level and 10,000 feet is very significant... 14.7 psia at sea level and 10.1 psia at 10,000 feet. 11 inches water column only adds about 0.4 psi to that.

This means that there is less actual gas flow at elevation than at sea level for a given liquid fuel composition. With the refrigerator, this is somewhat compensated by the fact that the temperature is usually much lower at elevation that at sea level in the summer, meaning that the refrigerator doesn't have to work as hard, and uses less fuel.

As one increases the butane content in the propane, the higher the inside tank temperature must be to allow fuel evaporation to continue. Look at the example of one versus two 100 pound bottle quoted above. With one bottle, the tank frost over, and fuel flow stops, because the tank cooled to below the fuel evaporation point. With two tanks, everything is fine. With two tanks, the evaporation load is spread over the two tanks. Now you have twice the tank surface area to release the cooling caused by fuel evaporation. With little or no frosting, the tanks can continue to evaporate fuel without problem.

Vic