Turning freezers off at selected times of day to save money, thoughts please.

[ericmark]

I have 4 freezers running, I have tried to get my wife to reduce frozen food, without any success. Colvid did not help as she now feels we should have a large stock of food, our back ground use of electric is around the 350 watt mark on average, which is just a little too high to last from sunset to 1 am when we get cheap off peak electric from our 3.2 kWh battery.

The battery hits the 10% around 11 pm, so we start using electric at peak rate, three freezers are close together, so if at 9 pm a timer turned them off until 1 am it would mean 24 hours power either at low rate or using solar.

It seems tempting as have spare plug in timers, but would it cause damage? Two freezers are inverter drives, and one old chest freezer. It was suggested by brother-in-law, but I am not sure worth doing?

 

[Wayners]

Freezer starts and stops like a fridge to maintain temperature.
Turning freezer off, it will need to work harder when you turn back on so nothing saved.
It's the standing charge of 60p a day that's the problem which we all pay regardless.

Re battery. Maybe you are correct. But my gut feeling is that it won't be worth it.

 

[StephenStephen]

A couple of thoughts...

I don't know if freezers do or don't mind being on timers - I'm also interested to hear about that...

Our freezer running cost massively reduced when we replaced our chest freezer with a commercial high efficiency chest freezer.

Having freezers in a cool place is going to reduce electricity use.

Ventilation around the heat output is particularly helpful.

My understanding (and anecdotal experience) is that full freezers are more efficient - it's worth considering tubs of water, or newspaper.

A chest freezer is likely to be more efficient - the cold air doesn't fall out when you open it.

I have thought myself of having the freezer off at peak rate time, but to be honest, it uses so little power that it's not worth to bother.

 

[Murdochcat]

I would start by using a device like this

Energenie ENER007 Energy Saving Power Meter Socket - Screwfix

Order online at Screwfix.com. Monitor and measure the energy use and costs of running household appliances. Simply plug into a powered mains socket and then plug any 13A rated appliance in. Discover which appliances use most energy, helping you lower power bills and reduce emissions. FREE next...

www.screwfix.com

and for each a week at a time to determine what power is used by each freezer. Then you need to decide what to do next but it might mean replacing one or more of them.

Fridges and freezers (especially old ones) use much more energy than people realise

 

[JohnD]

350W background is quite low. If you are fretting about that cost, stop. Suppose you saved 50W for ten hours. Not significant. Fit LED lamps throughout and the electricity cost is so low that it will not repay the cost of a timeswitch.

My background usage goes down to 250W at night.

If any of your freezers are old, they will be less efficient than a modern one.

If you have solar panels you can save more by running appliances in daylight.

 

[big-all]

my thoughts
a possible say 250w average over say 4 hours i 1kw so 1kw at cheap rate over normal rate saving perhaps 20p a day control gear costs perhaps £12 so could pay for its self quite quickly but if it goes wrong and your away for a few days 3 freezers full off food that needs to be eaten
actual costs depend on actual times and amounts

 

[Harry Bloomfield]

It seems tempting as have spare plug in timers, but would it cause damage? Two freezers are inverter drives, and one old chest freezer. It was suggested by brother-in-law, but I am not sure worth doing?

You could experiment with timing...

The longer a fridge/freezer runs in one go, the more efficiently it will be. Freezers are suggested to be happy without power for 8 hours. You could try cutting the power say - the 6 hours before off-peak, then it them catch up during off-peak.

Two savings to be had - one from a longer run of the compressor, a second one from pushing some of the consumption over to off-peak. The risk is, a possible power cut, after the freezer has been off for those 6 hours. It should harm the freezers, being off for those hours.

Log the normal consumption cost, then log it when turned off for those 6 hours. I would imagine you could cut the days running cost, by perhaps 1/3rd.

 

[ericmark]

I would start by using a device like this

Energenie ENER007 Energy Saving Power Meter Socket - Screwfix

Order online at Screwfix.com. Monitor and measure the energy use and costs of running household appliances. Simply plug into a powered mains socket and then plug any 13A rated appliance in. Discover which appliances use most energy, helping you lower power bills and reduce emissions. FREE next...

www.screwfix.com

and for each a week at a time to determine what power is used by each freezer. Then you need to decide what to do next but it might mean replacing one or more of them.

Fridges and freezers (especially old ones) use much more energy than people realise

I will use the energy meter and look at the actual run times, and see how many time per day they do switch on, that is a good idea. Maybe if I can confront my wife with the cost she may consider not keeping so much food in stock, I will use an Energenie unit but one of these I have one which only monitors and one which will switch and monitor, at the moment looking at the tumble drier, I will move it to freezers, and see average use.

The risk is, a possible power cut, after the freezer has been off for those 6 hours.

Not that much of a risk, as all on UPS, as long as battery is not under 10% they should still run.

My background usage goes down to 250W at night.

That is interesting, if the saving is small then not worth doing.

Freezer starts and stops like a fridge to maintain temperature.
Turning freezer off, it will need to work harder when you turn back on so nothing saved.
It's the standing charge of 60p a day that's the problem which we all pay regardless.

Re battery. Maybe you are correct. But my gut feeling is that it won't be worth it.

Yes it seems they do turn off/on, I did not expect the upright freezers to turn off/on as the commercial versions don't, clearly the chest freezer has no option it has to turn on/off/on as direct powered, however the inverter ones are much quieter, specially as they start, and no heavy start current, I would assume three phase motors, but they still turn on/off rather than adjust motor speed.

The chest freezer no qualms about, that can turn off for a time, but the upright are frost free, which means every so often the motor stops and a de-frost element switches on, and then back to cooling again, my worry is if the time clock turns off just as the defrost cycle is completing then the temperature may raise over a safe limit, so on reflection the uprights can't be switched off for a set time, only the chest freezer would be suitable. So will just test the chest freezer to see how long it runs for.

 

[Harry Bloomfield]

Here is my days consumption, for an idea...

The base minimum consumption, seems to be around 45watts, small peaks, fridges and freezer running.

 

[big-all]

another thought iff it has fast freeze turn that on overnight and off the rest off the time and that will bank some cold at cheap rate

 

[ericmark]

Here is my days consumption, for an idea...

That does help a little, but more interesting is import from grid

Up to 5 am on cheap rate so that OK, except for a shower and a small spike when making coffee the grid graph is above the 0 so not costing, and today the battery has plenty so likely I will get to 1 am, however I had forgot about auto defrost so only the chest freezer could be put on a timer, job one is measure what the chest freezer uses and see if worth doing.

 

[carmanmemoranda]

How much do the freezers cost to run would be the figure to find out

Then, is it effective to save it?

 

[ericmark]

Recent usage and average hourly usage are showing an average of around 23 watt average, and 63 watt each time the chest freezer turns on.

I looked at the upright, and realised they have auto defrost and how long they can be turned off for would depend where it was in the freeze/defrost cycle, so simply not worth the risk.

At 23 watt average the saving would be minimal, consumption is around 300 watt and even with 4 freezers running, that is only around the 100 watt, likely the TV is around 200 watt, and the living room lights 48 watt, so lights and TV would seem to account for a large chunk.

I went out today to play trains, and wanted to return with some thing for her in doors, and this was her, so you can see why trying to tell her how much her food storage is costing is a subject I am loathed to approach.

 

[Koolpc]

4 freezers!!!!!!!!!

Blimey, that is pure ridiculous.

 

[Harry Bloomfield]

4 freezers!!!!!!!!!

Blimey, that is pure ridiculous.

Yep! Marginally sensible, for a very large family - especially, if they have access to bulk buy cheap meats..

We two manage perfectly well, with a fridge + small freezer above, for storing the regular small items, plus an upright freezer in the utility, which is a main frozen food store. That last, usually gets a restock, once per month, and also stores any batch cooked food.

Used to have a large chest freezer, in the utility long ago. That proved to be rather silly - it just filled up at the bottom, with frozen food which never ever moved.