|
|
Author |
|
Message | |
|
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: 28118 Location: escaped from Swindon
|
|
|
|
|
ken69
Joined: 17 Jul 2005 Posts: 316 Location: Norfolk
|
|
|
|
|
dougal
Joined: 15 Jan 2005 Posts: 7184 Location: South Kent
|
|
|
|
|
ken69
Joined: 17 Jul 2005 Posts: 316 Location: Norfolk
|
|
|
|
|
ken69
Joined: 17 Jul 2005 Posts: 316 Location: Norfolk
|
|
|
|
|
Lozzie
Joined: 25 May 2005 Posts: 2595
|
|
|
|
|
Cathryn
Joined: 16 Jul 2005 Posts: 19856 Location: Ceredigion
|
|
|
|
|
sean Downsizer Moderator
Joined: 28 Oct 2004 Posts: 42207 Location: North Devon
|
|
|
|
|
jema Downsizer Moderator
Joined: 28 Oct 2004 Posts: 28118 Location: escaped from Swindon
|
|
|
|
|
sean Downsizer Moderator
Joined: 28 Oct 2004 Posts: 42207 Location: North Devon
|
|
|
|
|
jema Downsizer Moderator
Joined: 28 Oct 2004 Posts: 28118 Location: escaped from Swindon
|
|
|
|
|
dpack
Joined: 02 Jul 2005 Posts: 45520 Location: yes
|
|
|
|
|
dpack
Joined: 02 Jul 2005 Posts: 45520 Location: yes
|
|
|
|
|
Lozzie
Joined: 25 May 2005 Posts: 2595
|
|
|
|
|
|