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unbob's avatar
unbob
Explorer
Aug 13, 2014

Ambient temperature effect on refer interior temp

I know that RB gas/electric refrigerator efficiency is degraded as ambient temperature increases, but at what rate? For example, yesterday's outside temperature reached 107F at my location and my refer temp did not drop below 62F. Yes, I expect a higher refer temp with such high outside temp but not that much!

I strongly suspect I have other issues with my 9-year old Dometic unit but would like some feedback re the ambient temp effect question.

tia, Rob
  • There are two reasons high temperatures degrade refrigerator performance- the obvious lack of insulation , and the fact that at a certain point, which IIRC is around 120°, ammonia will not condense out in the condenser, which stops cooling all together.
    The same issue exists with compressor based units, but they draw conditioned air from the interior, generally.
  • Fred, thank you. Another tip offered...

    When spooning stuff like spreads, and mayo, I first dunk the spreader into a glass of water laced with a few drops of bleach. Kills all virus and bacteria. Does not hurt the taste. When things get really warm the butter goes in the freezer, same with margarine. nothing like opening a tube of margarine to find slopping yellow oil...yuck. But even then, I'll "paint" liquified margarine on toast, and dribble it over potato and vegetable. All that disappeared when I got that monster Viking refrigerator for the umbilical house then clad in with 2" of rigid foam. A person is put on a fast track learning curve down in the tropics. It's really mean with the mold, mildew and food poisoning issues.
  • Another thought.

    We had a freezer in a commercial kitchen that was not keeping temp, like it had all year long. Turns out that they started making ice in it at night. They would fill a tray with about 20 pounds of water, and put that in around 9 pm.

    We changed it so that they would first fill the tray with ice from the ice machine, then fill it with cold water. This means that only 4 pounds of ice is made, but they still have a 20 pound of ice to use the next morning.

    Freezing ice consumes a lot of energy. Each pound is 144 Btu's of cooling to change from water to a solid, so 20 pounds is around 3,000 Btu's of cooling just to make that ice. The freezer compressor was only around 1,200 Btu's capacity, even for a large 2 door freezer, and that used most of it's capacity just making that small amount of ice.

    So if you are making a large amount of ice, buy some instead, and don't make to much ice in the freezer.

    I would not worry about mayonnaise, as it can tolerate some heat. My aunt used to store hers in the kitchen cabinet, I would not eat it anymore, but still it can handle 60F for a couple of hours.

    Yet chances are that all the food in your refrigerator has been exposed to over 41F for more than 10 - 15 hours over the past few days. That makes all of it a bit of a risk to eat it.

    Also check the refrigerator. If not properly level, it can have problems. It does not need to be perfectly level, but will perform better level. It is only when way off level that the ammonia and water mixture will not return to the boiler properly that you have extreme problems.

    Chances are that switching from electric to gas will go a long ways to solve your problem. I use a remote sensing thermometer, so that I can monitor the inside temps without opening the door.

    Fred.
  • At 107 outside, I would not expect much cooling from my refrigerator either.

    Was it running on gas or electric?

    If on electric, that is probably the problem. The 300 watt heating element only puts out about 950 Btu's per hour, while the gas burner is 2,200 Btu input, or around 1800 output, or twice as much cooling.

    Because tomorrow is not likely to be cooler, I would suggest freezing a bowl of ice tonight, and move it into the refrigerator section around 10 am tomorrow, to help keep the temps close to 40 as possible. Some foods degrade quickly between 45 and 140F. So keeping it below 45 is essential, and below 41 is required by the Health Department in every state.

    Things like butter and fruits will not be damaged in the refrigerator at 60F, but any meats should be considered at risk of contamination. Raw eggs can survive 50F for a while, but I heard that hard boiled eggs should not be stored above 41F.

    When it is 100F outside, I think that only ice will keep the refrigerator from overheating. I used to put cubes in the drip tray, so they can melt, and the water goes out with the other condensation. About 10 cubes will work, at 10 am and then check around 2 PM to add about 10 more cubes.

    Fred.
  • I gave up and bury a 7-day Igloo ice chest in the sand. Chest is wrapped in a thick comforter, both are put inside a 50 gallon trash sack. Hole is dug, chest falls into hole. Comforter inside bag is wrapped atop lid. Then light stuff is piled atop all. When I sold my crown the 300 lb SunFrost went with it. This probably won't make you feel any better but not even a 200 lb Servel, with fans, juju sticks, shade and curses could keep food from spoiling when temps got as hot as yours. Buy in small quantities, and keep the most sensitive stuff jammed against the colder condenser coils. Throwing money at it is about as useless as flogging a horse skeleton when it gets that hot. Wue le Vaya Bien.
  • With 107 temp you mentioned that's asking a lot for an rv unit. I've often thought my dometic was not working properly when in 100-105 degree temp and my unit was maybe 58-60*. I tried an exterior fan. It only helped a little. It doesn't help when my kids open it once or so an hour. Whenever it's lower then about 85*outside the frig works fine, 37-40*. 107* is just too hot for an rv frig in my opinion.
  • 40* is the max. safe temperature for food in the ref.
    I would be careful eating things that got as warm as you described. If the temp. was above 40* for two hours or more, I would not eat any meat or dairy products, or things made with dairy, like mayo.

    Or if you decide to anyway, don't get too far away from the toilet. You may need it real soon. ;)
  • And though not always possible, the MH should be parked with the reefer side in the shade as much as possible.

    Something I'm going to try is a large piece of the reflective bubble wrap. Maybe one of the large pieces for MH windshields. Then take two of the rubber suction cups with hooks on them to hang the insulated bubble wrap on the outside of refer. The hooks would hold it away from the refer back to provide shade to the refer and allow air to flow through the refer vent. It can't hurt, we'll see if actually helps.

    Bill
  • Hi Rob,

    Add a chimney fan, and a fan to draw air over the cooling unit inside the fridge.

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