Freezer Question

[rtbcomp]

Just blagged a small Norfrost chest freezer, but I don't have the instructions.

There's an illuminated switch next to the thermostat which I assume is a "fast freeze" switch or suchlike. What exactly does it do? does it bypass the thermostat so the temperature drops below the set point or does it actually make the temperature drop more quickly?

Will the freezer run continuously with this switch set to on?

Ta!

 

[cumbriasteve]

From our freezer handbook:

If you are placing a large quantity of unfrozen food in your freezer it may raise the internal temperature and illuminate the red warning neon, when placing such an amount of produce into the freezer select the fast freeze option for a period of time until the produce is frozen.

I know we left it on once for a day and it seemed to be a lot colder inside.

 

[Robotstar5]

As above, but my handbook warns not to leave on more than 6 hours, and no I haven't tried it to see what happens

 

[Justme]

My new freezer came with the instruction to turn it on to fast freeze up to a day before adding large amounts of fresh food or just before smaller amounts & to leave on till frozen.

Past experience says that using it will lower the temp from standard but it wont reduce the cooling time on the first use as the pump will be working solidly any way.

 

[rtbcomp]

Thanks for the replies.

It looks like it bypasses the thermostat to drop the temperature right down so when you put fresh food in it freezes faster due to the lower temperature, rather than a means of reducing the temperature more quickly.

I have this cunning plan to emulate the fast freeze switch with a time switch to deep freeze on Economy7 (half-price electricity), sort of a storage heater in reverse.

 

[Shox Dr]

Will that make any difference to your lecy consumption? I read the meters every week, at the same time (Mon 6pm).The biggest underlying consumers of power in our house (inc whokshop) are the fridge and freezer using around 40-45 units a week.*

And while I can see the method in your madness. A full full freezer that is not opened too much. Well sited to prevent ambient temps fluctuations, with good air circulation around the radiator. Would be a better and far easier.




*our house uses around 40-45 units while we are away.
45-65 in summer, and 65-90 in winter this is based on the last 6-7yrs of data.

While we are on the subject is there anyone good with spreadsheets, that could read me a few macros to convert said data into graphs

 

[rtbcomp]

Will that make any difference to your lecy consumption? .......

Don't know - I have a power consumption gizmo that I can program with cost per unit &c and get a readout of running cost over a period, so it's a case of experimenting.

In theorey it should - I have a certain mass to keep at an average temperature, if I can attain that by using half-price electricity I should make a saving.

The catch is not to let the temperature rise above -18 degC.

 

[Justme]

I have done this. Just using a simple plug in timer switch. Freezer on fast freeze would get to at least -24c by 7am & still be colder than -18c when the power came back on. This was a large commercial chest freezer. You will use more units but pay less total money for them.


You could wire in an over ride so that if the temp goes over -18c it will turn the power on for say an hour. Personally I would not be worried if it got slightly warmer than -18c for domestic usage. Ours was for commercial use so had to maintain the min legal temps.

 

[rtbcomp]

By using the timeswitch on the fast-freeze circuit only, the thermostat will cut in anyway if the temperature rises too much.

I have fridge with a duff thermostat which I have shorted out. I run the fridge from a 24 hour segment timer, I just have to adjust the settings for summer and winter (at least I used to have to).

 

[PTvor]

I

You could wire in an over ride so that if the temp goes over -18c it will turn the power on for say an hour. Personally I would not be worried if it got slightly warmer than -18c for domestic usage. Ours was for commercial use so had to maintain the min legal temps.

The freezer section of a lot of cheaper domestic fridge/freezers doesn't have a thermostat, it relies on the fridge section's thermostat.

If the kitchen is cold in winter and the fridge isn't on the highest settings, the freezer can thaw out, as I found. I'd have thought they'd have had a emergency thermostat for the freezer, but no, anything for the cheapest.

When I used a cheap inside/outside thermometer to watch the freezer temperature, I found it was all over the place. Generally -25 to -18, but sometimes up to -5. That was when the fridge thermostat was set to keep the fridge cold.

 

[the snooper]

If the kitchen is cold in winter and the fridge isn't on the highest settings, the freezer can thaw out, as I found.

some of the auto defrost fridge / freezers develop faults where the auto defrost heater stops working then the pipes from the compressor freeze up externally and partially internally restricting the flow if it only has one compressor the fridge appears to be cold while the freezer defrosts and your food is ruined

 

[PTvor]

some of the auto defrost fridge / freezers develop faults where the auto defrost heater stops working then the pipes from the compressor freeze up externally and partially internally restricting the flow if it only has one compressor the fridge appears to be cold while the freezer defrosts and your food is ruined

Interesting, but this fridge freezer was seriously cheap (£180) and I don't believe it has an auto defrost heater. The problem appeared when the weather was cold and disappeared when the fridge thermostat was set to colder.

The assumption it's based on seems to be that if the fridge is cold enough, the freezer will be dragged along and that works if the fridge has to work to keep cold. A friend had a similar problem with a new fridge in a large, very well insulated kitchen and I recall he put in an emergency override.

As for rtbcomp's problem, making the most of Economy 7, I smell a microprocessor application in the making.

 

[eil]

Thanks for the replies.

It looks like it bypasses the thermostat to drop the temperature right down so when you put fresh food in it freezes faster due to the lower temperature, rather than a means of reducing the temperature more quickly.

I have this cunning plan to emulate the fast freeze switch with a time switch to deep freeze on Economy7 (half-price electricity), sort of a storage heater in reverse.

Yep you are right there the fast freeze switch just bypasses the thermostat.

 

[rtbcomp]

........
As for rtbcomp's problem, making the most of Economy 7, I smell a microprocessor application in the making.

No chance! The next generation of freezers will probably sense the mains frequency and switch on when demand on the grid is low, ie when the frequency rises slightly. This coupled with a Very Smart meter will give the consumer a variable tariff.

So far this freezer has taken nearly 17 hours to freeze 3 litres of water, and the outside panels feel quite cold, so unless I can add extra insulation I doubt whether my Cunning Plan will work.

 

[Fintray]

While we are on the subject is there anyone good with spreadsheets, that could read me a few macros to convert said data into graphs

Is your data in Excel?

 

[Shox Dr]

Is your data in Excel?

Yes it is.

 

[Justme]

No chance!

So far this freezer has taken nearly 17 hours to freeze 3 litres of water, and the outside panels feel quite cold, so unless I can add extra insulation I doubt whether my Cunning Plan will work.

Is it an empty freezer? If so the "stored" energy level in the air is quite low.

Its like thermal mass in a house.

 

[rtbcomp]

It's empty apart from a couple of 1.5 litre bottles of water. Because the mass is low it should cool down more quickly, although the temperature drop will slow down as the water freezes due to the latent heat of fusion.

I've found a user manual PDF and it would seem to be working normally, it's just a cheap & cheerful freezer.

 

[normspanners]

What p***s me off is the teenage son stands for 5 mins looking into our upright freezer before picking a item to cook, then walks to the deep fat fryer switches that on, puts the Frozen chips in the basket walks back to the open freezer puts the bag back in, and only then shuts the door. I say why didnt you shut the door he says I did.HUM
YES now all the cold air is in the room !! and the freezer has to work for an hour to re chill its self.

 

[rtbcomp]

LOL - It's like the exam question

Q - "What happens if you leave a fridge door open in a closed room?"

A - "I get a clip round the earhole."