Fridge/freezer on Economy 7 possible energy-cost-saving trick?

wrf12345

My  newish fridge is supposed to survive 48 hours without electricity if the door is not opened so that suggests that it could be run at the cheap rate and then turned off during the day if it was placed in an unheated area of the house and the door was only opened once or twice and very quickly.

devondiver

victor2 said:

. . . friends who . . . rely on solar/battery to run a large fridge/freezer . . . They still have to switch off the fridge at night in the winter to prevent the (expensive) battery system shutting down completely.

From an energy-saving standpoint this sounds like the perfect situation for a 'cold bank' (i.e. PCM - phase change material) type solution rather than an 'electricity bank' (i.e. batteries) which incur substantial efficiency losses in converting from one form of energy to another. If a freezer 'cold bank' used a PCM with a fusion temperature close to the optimum (-18C?) the freezer motor could be switched off for long periods, perhaps when the sun was not shining or electricity supply was down (or expensive), with no concurrent rise of storage temperature until the 'cold bank' was fully melted.

theoretica

Another significant point will be where is the thermostat that turns the fridge/freezer on?  I remember learning that many have a single cooling circuit, which is controlled by the freezer temperature - the fridge on top is just sort of bonus cold...  So keeping the fridge area cold might do very little for power use.

devondiver

wrf12345 said:

My  newish fridge is supposed to survive 48 hours without electricity if the door is not opened so that suggests that it could be run at the cheap rate and then turned off during the day if it was placed in an unheated area of the house and the door was only opened once or twice and very quickly.

Are we talking fridge or fridge/freezer here? And what does "survive" mean? Is it that the temperature of the contents will not rise at all? - over 48 hours?

As you suggest, it probably depends to a degree on the ambient temperature surrounding the appliance. I know that in unheated parts of my house in winter I could probably do with no power at all to the fridge at times! But bear in mind that (most of) these appliances will not operate properly at low ambient temperature.

devondiver

theoretica said:

Another significant point will be where is the thermostat that turns the fridge/freezer on?  I remember learning that many have a single cooling circuit, which is controlled by the freezer temperature - the fridge on top is just sort of bonus cold...  So keeping the fridge area cold might do very little for power use.

Good point. Depends on the design of the appliance I suppose. Hard to believe that there isn't some 'smart' system which only supplies 'cold' when and where it is needed though. 

devondiver

FWIW - I now finally have a programmable dual-tariff power monitoring plug so I will be able test my theory. So - watch this space! 

redux

devondiver said:

FWIW - I now finally have a programmable dual-tariff power monitoring plug so I will be able test my theory. So - watch this space! 

Some of these tricks might cost as much as they save.

How much did that device cost?

I wondered about getting one of those mains adapters with clock settings and turn off the router at night. Might cost £7, might save £2 to £2.50 a year. Turn off the cordless phones too and make another few pence, but only if the phone charger is on the same socket. That was old unit prices though, maybe it's worth it now, but probably still won't get around to it.

Save more by skipping a meal out, or a couple of beers.

EssexHebridean

redux said:

devondiver said:

FWIW - I now finally have a programmable dual-tariff power monitoring plug so I will be able test my theory. So - watch this space! 

Some of these tricks might cost as much as they save.

How much did that device cost?

I wondered about getting one of those mains adapters with clock settings and turn off the router at night. Might cost £7, might save £2 to £2.50 a year. Turn off the cordless phones too and make another few pence, but only if the phone charger is on the same socket. That was old unit prices though, maybe it's worth it now, but probably still won't get around to it.
 <snip>

I’m guessing it’s not as fancy as it sounds - a Tapo P110 will cope with monitoring on dual rate, and shouldn’t have cost more than a tenner, so pretty reasonable allowing it’s a smart plug, and acts as a time-switch/scheduler too.

I wouldn’t turn your router on and off a lot by the way - it’s not generally reckoned to be great for the stability of your internet connection. And for goodness sake please do NOT turn off your router and your landline phones - you potentially leave yourself in a position where a 999 call overnight becomes impossible.

devondiver

redux said:

How much did that device cost?

Well I paid £21.99 for a Maxio Power Meter Energy Monitor Dual Tariff delivered. It's a useful gizmo for checking power use of all sorts of plug-in appliances. I ran it for a week on my fridge/freezer while I was away. I checked all the figures on my return but haven't really been able to analyse them yet. Even though I programmed in the 2 tariff rates and respective times it seems that the Maxio doesn't separate the usage into the two tariff totals. So not much help, yet. To get definitive answers I'll need to spend (waste?) a bit more time on it.

BTW - in case it isn't obvious - I am not expecting that this will save me significant money. Just to explore the idea that application of the principle in domestic appliances may be of some benefit. From my brief internet browsing it seems that there are already industrial applications of the principle but perhaps not in domestic appliances yet.

hardergamer

Deleted_User said:

"Since refrigerators account for the major share of energy consumption in homes"?  Really?  Are these homes without space heating or hot water?

I'd rather use the "phase change material" of molten salt in concentrating solar power stations with thermal storage than need everyone to change their refrigerator.

Large-scale renewables with energy storage means that there is much less of a peak vs off-peak anyway.

Think about it, most homes are empty throughout the day from 7am-5pm when must people work and their kids are at school, The fridge/freezer is the only major electrical item always left on, and in my own home it uses by far the most electrify for any single item at 1.5kwh a day, next is my laptop at 300wh then my kettle used 8 times is 180wh, microwave 10 minutes 150wh, 3 hours of a slow cooker 120wh, 2 hours of TV in the evening 120wh, 10 minutes use of air fryer 100wh, toaster 5wh, 10 hours of 4.5w lED lights 45wh, all tested with a KillerWatt meter for my solar installation.

If you did a little research, you will find on average a fridge/freezer is the biggest single electrical usage in the home.