Winter 'Fridge Covers

Aug 2, 2006
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I have been towing for over 40 years generally not during deep winter. This last December & January we spent 10 days on a CL over the Christmas and New Year period. I had terrible trouble getting or full size Thetford fridge in our Bessacarr 645 to freeze down until I saw a virtual "throw away line" in the instruction manual - viz. "If using in air temperature below 8 deg C Winter Covers should be fitted.
Covers were sourced and eventually fitted and the performance of the 'fridge was transformed with the freezer dropping to around -15 deg C. (We keep a thermometer in the freezer),
Lesson learned. If winter caravaning don't forget the winter covers (but don't forget to remove them when the weather warms up!!).
 
Nov 11, 2009
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David_5127637 said:
I have been towing for over 40 years generally not during deep winter. This last December & January we spent 10 days on a CL over the Christmas and New Year period. I had terrible trouble getting or full size Thetford fridge in our Bessacarr 645 to freeze down until I saw a virtual "throw away line" in the instruction manual - viz. "If using in air temperature below 8 deg C Winter Covers should be fitted.
Covers were sourced and eventually fitted and the performance of the 'fridge was transformed with the freezer dropping to around -15 deg C. (We keep a thermometer in the freezer),
Lesson learned. If winter caravaning don't forget the winter covers (but don't forget to remove them when the weather warms up!!).

Useful for when washing the van too.
 
Jun 17, 2011
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I always used them until I had a fridge fire. The fire wasn’t linked to the covers but technician advised not to use them and haven’t for about 6 years and we are out all winter. Never had a problem with not getting cold enough but we only run it on level 3. We have just had a new caravan with a Dometic fridge and dealer reckons the covers are not necessary.
 
Mar 14, 2005
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waffler said:
I always used them until I had a fridge fire. The fire wasn’t linked to the covers but technician advised not to use them and haven’t for about 6 years and we are out all winter. Never had a problem with not getting cold enough but we only run it on level 3. We have just had a new caravan with a Dometic fridge and dealer reckons the covers are not necessary.

It is perhaps foolish to ignore the instructions supplied by the manufacturer, I doubt the fitter has the financial clout necessary to fully test the product for compliance and proper safe operation.
 
May 7, 2012
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We fit them for cold weather use and to prevent excess water getting in through the grills when washing the caravan. My feeling is that it is worth the cost of these just for the water prevention alone. It is essential they are removed in order to allow the fridge to work correctly in warmer weather.
 
Jan 28, 2019
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Have found them invaluable for winter trips - just wish they weren't so darned expensive.
I feel they should be included with any fridge installation - not supplied as an expensive extra.
 

Mel

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Mar 17, 2007
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Hi. We have caravanned in winter temperatures ( certainly below 8C). Never used fridge vents and not seemed to have a problem.
As every day is a school day, can someone explain how they help. I like to understand why and how things work
Thanks
Mel
 
Mar 14, 2005
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Hello Mel,

You asked so ;-

Caravan fridges use a process called absorption, and it uses a sealed continuous loop of pipe which has a controlled amount of a refrigerant fluid inside. The loop of pipe has three distinct areas, an oven, an evaporator and a condenser. The evaporator is inside the fridge at the top and provides the cold surfaces. The condenser is on the back of the fridge and it provides the surface that gets rid of the heat. And the oven is near the bottom under the condenser radiator. The system is sensitive to orientation, and will not work if it's adversely tilted.
The oven can be heated by any external heat source such as gas, 12V or mains which is why its so effective for caravans.

The heat from the oven section causes the fluid to flow around the pipe circuit. Initially it compresses the gas by heating it, and it passes into the condenser coil in the back of the fridge. Here the compressed gas looses its heat and it condenses into its liquid phase as it rises up the condenser coil.at the top of the condenser the pipe narrows as it goes inside the fridge. and as it enters the evaporator coil inside the fridge, the pipe widens and the liquid refrigerant has to expand to fill the space in doing so it reverts to a gas, but it needs external heat energy to do this which it gets by drawing heat from inside the fridge effectively cooling the fridge. The now expanded gas makes its way back to the oven where it is re compressed and starts the cycle again.

Its a carefully balanced thermo dynamic cycle which can be upset by environmental temperature conditions. If the ambient air around the condenser coil at the back of the fridge is too cold then the liquified gas may be cooled too much and it might collect all the systems fluid in the condenser leaving non to expand in the evaporator. The winter covers restrict the amount of cold air reaching the condenser coil ensuring the cycle continues. Equally excessively hot weather will also stop the cycle working by preventing the refrigerant from properly liquefying in the condenser, so some people fit powered fans to improve the heat exchange.

Domestic fridges also have both the Condenser and evaporator coils but the oven is replaced by a much more effective mechanical compressor. These can usually operated over a much wider ambient temperature range, but a word of warning, Many domestic freezers are designed to operate inside houses, and some do not work anywhere as well if used in a garage where the ambient temperature can drop much lower than inside the house. Check the installation instructions for the required ambient temperatures.
 

Mel

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Mar 17, 2007
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Thank you for your clear and understandable explanation. Now I get it. :cheer: Wish my Physics teacher at school had been as clear; I would have got a better A level grade.
Mel
 
Mar 8, 2009
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Do you know we've caravanned for 40+ years, all year round, and we've changed our van every 4/5 years. I think each time we have changed our van the fridge vent shape/design had changed. Going on 'site gossip' (pre internet!) we were led to believe we needed vent covers for winter use. Finished up with several different 'sized' useless setsas each van different!. - So last 2 vans have not had fridge vent covers and still winter caravanning and 'do you know', - haven't noticed the slightest difference in the fridge operation!! -- Can we have our money back please?
 
Jan 28, 2019
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Simple solution to that - pop them on eBay and you will almost certainly get at least half of your money back.

By the way, we have loads of trees in our garden and the vent covers keep all the autumn leaves out and are a bonus when washing the caravan.
 
Nov 16, 2015
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We have caravanned at minus Centigrade temps, without the vent blockers and have never experienced problems. Keps the lager and wine cold enough. Oh and the wife says the food stays fresh as well.
 

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