Freezer efficiency, SAVA plugs, etc

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Freezer efficiency, SAVA plugs, etc
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dougal

Joined: 15 Jan 2005
Posts: 7184
Location: South Kent

Posted: Sat Jul 30, 05 2:47 pm Post subject: Freezer efficiency, SAVA plugs, etc

IMHO, this deserves a thread of its own

ken69 in the Norfrost freezer thread wrote:

..a standard fridge/freezer... Think it's 2AA.Together with SAVA plug £20 (which I have yet to research) should cut the costs down. In place of SAVA plug perhaps a stndard timer (3 for £10) would do. Guessing now 1hr on 1hr off.

I'd never heard of SAVA plugs before.
I found their company's description of their operation here:
https://www.savawatt.com/appdetails.asp?id=3
They claim to reduce the power consumed by mains electric motors running on part load.
I know very little about AC motor theory, but this concept is somewhat surprising as I would have assumed that the electrical power consuption for any significant load would be dependant on that load (and the unavoidable motor losses - bearings, windage, etc), and not on gadgets in series with the motor.
You might be cutting the consumption of the motor, but it would be reducing its power output, so that it would have to run longer to do the same work.
Hence my gut reaction would be to dismiss it as mumbo-jumbo alongside car fuel-line gadgets that claim "sonic" or "magnetic" means of improving mpg.

Does anyone know any more about these things?

Timers offer scope for *cost* reduction, rather than efficiency improvement. But *not* used as Ken suggests, 1 hour on, 1 hour off. I can't see that achieving anything.
Rather, a timer could improve the use of Economy7 power, by switching the freezer off for an hour or so before E7 came on. If the freezer isn't opened in the late evening, this shouldn't cause the temperature to rise significantly in that time.
After E7 is on, the freezer could have a good longer run (on E7) to regularise matters.
On a 1 hour hold-off, and assuming (inaccurately but for simplicity) that the freezer's consumption is uniform through the 24 hour day, my arithmetic (based on 8p peak, 3p E7) suggests that there might be a saving of just 3% on the cost of the electricity used.
An additional saving would be possible if the freezer controller "knew" when dawn was coming and deliberately "charged up" on cheap E7 electricity - but I don't know of this facility in a domestic model. One could imagine a similar facility that optimised (minimised) evening consumption in advance of the E7 start...

The freezer surroundings matter. Cold and even slightly draughty (but dry) would be good... The rationale is to reduce the temperature difference between inside and outside, reduce the entry of warm air on opening, and help the condenser (radiator), motor and compressor shed heat more effectively.

Apart from the look of the thing, there's nothing to stop you adding to the insulation of your freezer. See here:
https://www.theyellowhouse.org.uk/themes/appli.html#a14
but *please* note the comments about *not* insulating/boxing *in* the condenser/radiator - you want that to *lose* heat as effectively as possible... (but how can you use it?)

jema
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 28111
Location: escaped from Swindon

Posted: Sat Jul 30, 05 2:55 pm Post subject:
I have heard of this one before and had a similar sceptical reaction but can't recall where the debate I read was.

ken69

Joined: 17 Jul 2005
Posts: 316
Location: Norfolk

Posted: Sat Jul 30, 05 4:10 pm Post subject: freezer controls

Hi Dougal...not sure where I got the Sava plugs suggestion from ..perhaps google..alt.energy homepower or google alt.energy.renewable..but havn't researched same..but brother in electrical business can't find same in product supply books, but suggests segment timer would do.So....1hr on 1hr off is initial thinking..havn't done it yet...and realise freezer would have to play catch up depending on openings and nightime etc....Am presently on Powergen Age Concern tariff..and discounts and cold weather payments cancel out standing charge..not on Economy 7.Am living in semi detached 3 bedroom heavily insulated house, but nonetheless 3 sides to the wind.

dougal

Joined: 15 Jan 2005
Posts: 7184
Location: South Kent

Posted: Sat Jul 30, 05 4:25 pm Post subject: Re: freezer controls

ken69 wrote:

... brother in electrical business ... suggests segment timer would do.So....1hr on 1hr off is initial thinking..havn't done it yet...and realise freezer would have to play catch up ...

I can see that there would be a small saving by preventing the thing using peak rate power just before E7 kicks in. Hence my suggestion of turning it off (with a timer) for an hour or so at the critical time (late evening). But it seems to be a tiny saving.

But I honestly cant see the point of turning it on and off as your brother suggests. Anything you save in one hour will be lost the next as the machine tries to regain lost "coolth".
Any saving from the higher average temperature would be more easily obtained by tweaking the thermostat. But either way, it would be at the expense of the storage life of the freezer contents.

ken69

Joined: 17 Jul 2005
Posts: 316
Location: Norfolk

Posted: Sat Jul 30, 05 4:49 pm Post subject: freezer controls

Hi Dougall...my interest in this started when I read about SAVA plugs..perhaps on ACL..or Google..anyway..my electrical brother had trouble with his freezer thermostat, so he disabled it, put in a timer and it's been working ok for several months..that is not to say it's more economic..but it saved him buying a new freezer .So once he mentioned this I figured ..maybe..just maybe..I could save a shilling...the answer might be in insulating the pantry from the heat of the house..it might be in using a timer..can't see me paying out £20 for a SAVA plug anyway.Second thinking is ...is a fridge or freezer necessary.That's worth a thread on it's own.

ken69

Joined: 17 Jul 2005
Posts: 316
Location: Norfolk

Posted: Sun Jul 31, 05 7:22 am Post subject: SAVA plugs and insulation
Just read your yellowhouse link, Dougal, Thank you. Might do that. have the Celotex and shiny bubble insulation.

Lozzie

Joined: 25 May 2005
Posts: 2595

Posted: Sat Mar 04, 06 5:17 pm Post subject:

resurrecting old thread as have been considering SAVA plug again.

Idea seems to be that it allows full current in initial stage of motor operation, thereafter restricts power flow and motor doesn't actually USE that much electricity once operational.

Opinion still divided here - but the websites I have looked at seem in favour.

Wondered if anyone had had further experience since this thread was last used?

Cathryn

Joined: 16 Jul 2005
Posts: 19856
Location: Ceredigion

Posted: Sat Mar 04, 06 5:38 pm Post subject:
All I can add is that I bought one from C.A.T. and it's on my fridge freezer. Seemed mighty expensive at the time so I am not going to read this thread anymore because it's too late if they are useless

sean
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 42207
Location: North Devon

Posted: Sat Mar 04, 06 6:36 pm Post subject:
ISTR that they're only supposed to work on older model fridges/freezers. No idea why though.

jema
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 28111
Location: escaped from Swindon

Posted: Sat Mar 04, 06 6:42 pm Post subject:
All these sorts of things, imply some inexplicable conspiracy by ALL manufacturers to waste energy

sean
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 42207
Location: North Devon

Posted: Sat Mar 04, 06 6:46 pm Post subject:
I'm not sure that it takes a conspiracy theory. Most people won't pay more for energy efficient goods, so if you can shave a few pence off your costs by not worrying about efficiency too much as a manufacturer why wouldn't you? Those 'aspirational' SMEG fridges have rotten efficiency ratings but sell in huge numbers.

jema
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 28111
Location: escaped from Swindon

Posted: Sat Mar 04, 06 6:48 pm Post subject:

sean wrote:

I'm not sure that it takes a conspiracy theory. Most people won't pay more for energy efficient goods, so if you can shave a few pence off your costs by not worrying about efficiency too much as a manufacturer why wouldn't you? Those 'aspirational' SMEG fridges have rotten efficiency ratings but sell in huge numbers.

Do they say these plugs only work with certain brands? What about all the "a" rated appliances?

dpack

Joined: 02 Jul 2005
Posts: 45460
Location: yes

Posted: Sat Mar 04, 06 10:05 pm Post subject:
smeg is a red dwarf swear word , go wash yo mouth

dpack

Joined: 02 Jul 2005
Posts: 45460
Location: yes

Posted: Sat Mar 04, 06 10:08 pm Post subject:
i really need a good chest freezer so what do folks reccommend .

Lozzie

Joined: 25 May 2005
Posts: 2595

Posted: Mon Mar 06, 06 9:04 am Post subject:
Advertise for one on Freecycle.

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