Posted on 30 October 2011 at 12:19h

Earlier this year we bought a new fridge, one of those retro ones. Ever since we had it we have been a bit disappointed because it simply doesn't make the contents cold enough. The other problem is that the switch that turns the fan on when the door is close is not aligned properly so the fan doesn't come, what I hadn't realised was that this switch also turns off the interior light. So if the interior light is always on then maybe its heating the inside of the fridge stopping it getting cold. So about how much heat does the heat pump remove and would this little light bulb make that much difference?

I estimate that to cool down 1 litre of water from room temp to 4°C would take about an hour. This is based on experience of putting Jelly in the fridge to set and is a very rough estimate but can't be that far out. So the amount of energy lost from the water = 4200 x 26 = 109200J

If this is lost in one hour then the energy lost per second =  30.3 J

That's 30W. And what is the power of the light bulb? Yep, 30W

No wonder the pump is working almost all the time.

I have now solved this by sticking tape over the switch, the problem now is that the light doesn't come on when I open the fridge door. A minor inconvenience. Just have to move that clip on light you can see in the photo over the oven, placed there because the lights in the cooker hood don't work either.

Since writing this blog entry I have looked inside the fridge and seen that the light bulb actually has a power of 15W. The previous value of 30W came from the manual supplied with the fridge. Just goes to show how careful one should be when looking up data. It also explains why the inside wasn't room temperature.