Summer/winter Fridge performance

[Brendan DJ Murphy]

Just recently had a new fridge-freezer installed. Its is an integrated design to blend into our new fitted kitchen. (air vent fitted in plinth under freezer)

I generally dont bother reading the instructions for items as simple as fridge/freezers.

Basically, just switch it on and set the dial. 1=low (warm) 9=high (cold)

However, the instructions say that in extreme high ambient temperatures (like our recent weather) then set the fridge to a LOW number. During the winter, the instructions advise using a HIGH number.

This is contradictory to my own thoughts and logic.

Surely in the summer, to get the fridge extra cold, I thought a higher setting is best.

Can somebody explain why the instructions recommend a low setting for the summer?

Brendan

[N. Thornton]

Hi. Why would you want it set colder in summer?

Regards, NT

[Christian McArdle]

It is because your fridge freezer has a single compressor for the fridge and freezer sections. Because of this, the freezer bit is only freezing when the fridge demands cooling.

In winter, the fridge will hardly need cooling at all if it is set too low. This means the freezer is effectively turned off and will defrost. If you turn the setting up, the fridge will turn on occassionally, ensuring the freezer works. In summer, the opposite happens. At a high setting, the fridge is on almost constantly, meaning the freezer section gets too cold, leading to wear, frosting up and worst of all, rock solid ice cream.

These problems can be fixed by having two compressors, and hence two independent thermostats. This would be found on more expensive (or well designed) models.

Christian.

[L Reid]

Is it not due to the difference in ambient temperature affecting the efficiency of the fridge? What I'm getting at is in summer it's easier to vapourise the coolant, so the freezer is more efficient than in winter when it's colder and therefore more difficult to vapourise the coolant. Also from the point of view of a heat-engine, does a greater temperature difference not lead to higher efficiency (e.g. between a 0 deg fridge).

I also remember something about not keeping a fridge or freezer somewhere where it gets cold like garages.

[Christian McArdle]

The control is a thermostat, so basically directly sets the fridge temperature. Any changes in efficiency would be handled by changes in duty cycle of the compressor, rather than a change in temperature for a given setting.

Christian.