 Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me. |
Forum Index : Other Stuff : refrigerator insulation
  Page 2 of 2 |
|||||
| Author | Message | ||||
Ken. Newbie  Joined: 05/10/2008 Location: AustraliaPosts: 13 |
There is a European version of the eutectic type that started the revolution...they use their own compressors and have far better efficiencies compared to Danfoss. The name escapes me right now but a little research will find them...They also make DC household friges. As an ex yachtie and vetran of a few DIY fridges I can tell you there is a bit of work in building a good one..(Especialy in-situ in a boat) But it's all worth it when your beer is cold and your batteries happy! I killed a lot of good batteries with store bought fridges before I built my first fridge. On a household note...The "opal" series I think made by Kelvinator are VERY energy efficient. Ideal for off the grid. On a power note the Danfoss compressor is in fact an AC unit..It runs on I think 20VAC, Some times the conversion losses from Low voltage DC to 240VAC to run things is actually worth it as there are conversion losses you didn't even know about built in to your "DC" appliance. True that there is less amplification from 12>20v than 12>240v but sometimes a super efficient 240 version of something is better than the far more expensive and usually poorly put together DC version. I like AC...It travels better on long wire runs..switch gear and wire etc is cheap... Did that make any sense? 
ISOTHERM  I knew the name woul come to me after I hit "submit"  "Imagination is greater than knowledge" Albert Einstien |
||||
| Dinges Senior Member  Joined: 04/01/2008 Location: AlbaniaPosts: 510 |
Just some quick results from the results of the fridge modification and some other changes in power usage here. I nearly fell over backwards when I went to read the meter; I had to double-check the reading because I thought I made an error... For the record, the savings are the result of the next three changes I've made: 1- new refrigerator, class A (with extra external insulation added; see this thread) 2- new freezer, class A+ (no extra insulation added yet) 3- switching computer from full-tower desktop (P4/2.4, ~170W) to a notebook (P3/1000, uses 22-25W). (been using CFLs for many years, so no savings to be expected there) The above 3 changes have led to a use of 1749 kWh (over an 11-month period); extrapolating this to a 12-month period this gives a projected use of 1908 kWh/yr. However, the first 2-3 months of this billing period I was still operating under the old regime (no new fridge/freezer/notebook), so the savings for the next year will be even more: estimating the power use for 2009/2010 to be 1375 kWh/yr. The power company projected my use for this year to be 4567 kWh/yr. The real savings this year will become 4567 - 1908 kWh = 2659 kWh. Meaning power use will be down to 42%, a saving of 58%. For the next billing year, where the full savings of the 3 measures will be realized over the entire billing period, the savings will be about 70%, leaving the power-use only to 30% of what it once used to be. A much larger saving than I expected (and can actually explain). Anyway, what I'm trying to say: at this point in time, the new fridge, freezer and (second-hand) notebook have already paid for themselves, much sooner than I expected (13 months payback time for the fridge, about 2 years for the freezer). And it did not require any change in behaviour (the food is still cold and I still have internet). But I *will* be getting a very nice refund from the power company this year. The only thing that keeps annoying me now... why  haven't I done this much sooner?!
Peter. |
||||
oztules Guru  Joined: 26/07/2007 Location: AustraliaPosts: 1686 |
No doubt about it, the power savings far out weigh the power put out from your conversions 
Well done. ......oztules Village idiot...or... just another hack out of his depth |
||||
GWatPE Senior Member Joined: 01/09/2006 Location: AustraliaPosts: 2127 |
Hi Dinges, was the extimate based on the percentages you posted earlier? The change from a PC to a laptop makes a huge dent in the consumption, as you have now found as well. Does consumption compare well to my estimates of approx 2.5-3kWhr/person per day for an energy efficient home. Gordon. become more energy aware |
||||
| Dinges Senior Member Joined: 04/01/2008 Location: AlbaniaPosts: 510 |
Gordon, The estimate was made by the power company for billing purposes: they simply extrapolated a past trend in consumption. A clear illustration of the memorable words of my statistics professor: 'extrapolating the growth of a puppy leads to dogs the size of an elephant'. I just had a discussion with someone about the power company's 'estimating future power use'. Do they just extrapolate trends? If so, would they extrapolate a negative trend too? (my guess: no). If the increased use would show itself as a single-step increase, would they assume that a similar stepped increase would occur the next year? (my guess: yes). If a single-step decrease would occur in the past year, would they forecast a decrease in the next year too? (my guess: no). Etc. etc. Cynical as I am, I expect them to forecast power use in their favour. (of course, I've missed out on the interest on the refund I get; they won't pay me interest for effectively having lent them money during past year. My loss, but their gain) The 750 kWh/yr you mentioned was the saving (or at least, my estimate of it) of only the new refrigerator. Soon afterwards I also invested in a new freezer, and shortly before I bought a laptop (for the single reason of reducing power consumption; portability was and isn't an issue, as it's used in a fixed place and always grid-powered. I've accepted the decrease in power use this decision made. For none of my applications, the P3/1000 notebook is 'too light'. This includes 3D CAD work). The effects of those other 2 purchases weren't included in the 750 kWh/yr estimate. Solar batch waterheating is high on the 'to-do' list. Much higher than any windturbines. Especially considering the fact that water-heating is done electrically now. 
Peter. |
||||
| Dinges Senior Member Joined: 04/01/2008 Location: AlbaniaPosts: 510 |
[quote=Gordon]Does consumption compare well to my estimates of approx 2.5-3kWhr/person per day for an energy efficient home.[/quote] Gordon, at present (based on 11 months data, and only 9-10 months of the powersaving measures) the electrical energy usage is 1.74 kWh/person/day. If we take the effects of 2-3 months of missed savings into account as well, then electricity use will be 3.77 kWh/day, or 1.25 kWh/person/day. Not too bad, I think. Getting rid of the electrical boiler (waterheater) should slash that in half once more I think. Peter. |
||||
KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
Thanks, did ny old kelvinator freezer yeaterday, I figure the outlay on extra insulation will almost never pay itself off at $40. I added 13mm white foam to the sides 2 sheets at $12 a pop and for durability, I went for as light as I could get blue foam for the front, result is. Before: compressor running almost continuously After: compressor running almost never and cooling fins on the back not getting anywhere near as hot as before. Figure this is due to the compressor being nearly worn out, hotter it gets, less efficient it is, thus not getting as hot running much better. KW/hr meter used to show around 1KW/hr /day and now shows...... wait for it..... 250W/day. so for the $40 investment it will take give or take 400 days to pay for... which given the payback times for other things in the renewable game, this is not too shabby at all. When will someone come up with a method of running my three pool pumps, Got one for cleaning rarely used, one for the sand filter 6hrs a day summer, 2-2.5hrs winter both of these are 1.5KW pumps, and an 800 watt pump for the solar heating, run for 5-6hrs a day in summer- on a fancy electronic timer which senses the temp difference but additionally a time switch so it runs for 5mins on 5 mins off, heating result is the same for half the energy input. I figure this is the biggest chunk of my energy useage. Luck favours the well prepared |
||||
| Jarbar Senior Member Joined: 03/02/2008 Location: AustraliaPosts: 224 |
To remove the solar heating pump completely, how about a tee piece between the pump and filter.Then a ball valve on the tee and a solenoid valve after that.When the filter pump is running bleed off just enough pressure to get flow on the solar system and only when the solenoid is activated by the temperature sensing circuit output. Anthony. "Creativity is detirmined by the way you hold your tounge".My Father "Your generation will have to correct the problems made by mine".My Grandfather. |
||||
| Dinges Senior Member Joined: 04/01/2008 Location: AlbaniaPosts: 510 |
Very impressive results, Karl, much better than I achieved! All I got with the refrigerator was a 25% reduction in energy use. My new (still unmodified) freezer uses about double the 250 Wh/day that your old freezer uses. Haven't got around to adding insulation to the freezer yet, but reading about your results is very encouraging. The 40AU$ for materials surprizes me a bit, but even at that high cost it's still very much worth the effort if payback period is 400 days. And the higher your energy costs (here in NL 0.22 E/kWh = 0.30 US$/kWh) the shorter the payback period will be. A refrigerator/freezer is a heat pump: it pumps heat from a low temperature area to a high temperature area. Under normal conditions all the compressor has to do is pump out again the heat that leaks into the box through the walls, cracks, etc. Reducing those heat leaks will directly translate into lower compressor use and lower electricity costs. Generally speaking, heat pumps work at their most efficient when the heat difference they have to bridge (usually -18C inside the freezer and ~ +20C outside) is as small as possible. If the radiator on the back gets hot (say, 50C) that means the freezer has to bridge a larger temperature difference (-18 vs. +50), lowering efficiency (rather: coefficient of performance, COP)... and leading once more to a hotter running radiator...lowering efficiency... etc. When the radiator has a temperature significantly above that of the environment, it may be helpful to aid the natural convective cooling of it with some fans, as Vawtman suggested earlier in this thread. Guess that all this proves (once again) that it's much easier and cheaper to save energy than it is to generate, with returns that beat a savings account or the stockmarkets hands-down. Sad though, that the only difference between a plain freezer and an energy-efficient one is the thickness of the insulation (60mm vs. 90mm vs. 110mm), and keeping in mind the negligeable extra cost of the added insulation, I think it's about time we see some regulations that prohibit the manufacture and sale of energy-inefficient freezers or fridges, just like we've seen with the phasing-out of incandescent lighting; if the manufacturers and buyers of these appliances can't seem to make the responsible, right decision in this matter then maybe it's about time the government steps in and starts nudging them in the right direction. Won't be holding my breath for it though. Peter. |
||||
| KarlJ Guru Joined: 19/05/2008 Location: AustraliaPosts: 1178 |
I've considered doing away with the pump for the solar, would do it after the filter, the problem is the soleniod scenario complicated...read expensive.. and to boot the filtration pump is 1500W and the solar pump 800W, as the filtration pump is needed much less thus might not be a winner at all.... what i'd really like to do is the smartmeter and run filtration at off peak and solar obviously is stuck with on-peak rate. unfortunately a solar powered solution for the pumping is spectacularly expensive. got a power bill last week....... not good, think they have been estimating for a while, over the last bill 33kw/hr/day!! here's me thinking I'm doing great at 14KW/hr from the previous bills! thus ~6800 kw/hr/year =18.75 a day is probably a realistic figure given the darn pool pumps. still some work to do yet! fitted a solectair for home heating supplement the other day, we'll see how that goes soon (havent finished installing as yet) Luck favours the well prepared |
||||
| evoelzke Newbie Joined: 25/11/2011 Location: GermanyPosts: 5 |
Interesting experiment. I could reduce the power consumption even to 50% of the baseline. I did insulate the door as well with 10mm styrofoam and covered it under a white decorative foil. Here is a pic of my freshly insulated fridge including the door: 
It seems to look normal enaough cause visiting friends use that fridge for getting beer without noticing that it is modified. Here you got some more pics, measurements and the steps it took me: coolfridge Allen |
||||
| evoelzke Newbie Joined: 25/11/2011 Location: GermanyPosts: 5 |
Just an update after 10 months of running my self-insulated fridge: It does its job perfectly, efficiency is still as it was right after the insulation, which means an reduction down to 50% by the styrofoam insulation, there is no sign of condense water under the insulation, and the decorative foil looks excellent. I am very happy with my project. Have a look here for details please: insulate your fridge Allen |
||||
| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Just a random thought.... How about a dc refrigerator running from a battery that could be recharged at night using off peak power ? Cheers, Tony. |
||||
| Georgen Guru Joined: 13/09/2011 Location: AustraliaPosts: 462 |
Suppose chest fridge could be nice alternative. Opening doors would not make so much cold air to fall out. Also fridge could be set on timer to use off peak power. Would probably have to be set to operate on say +1 deg Celsius instead of standard +4 C Only danger that during the day fridge temperature rises above optimum temperature. During night maybe freezer could freeze some bottles with water that could be transferred to top of the fridge extending period of optimum temperature inside the fridge. Problem is that convenient automatic appliance would turn into something that has to be attended several times a day. George |
||||
Tinker Guru Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
Well, mine is an AC (modified) refrigerator running off a battery bank via inverter. The batteries are solar recharged during the day .
Regarding the modifications, I dismantled an old but working upright fridge, totally removing the housing so that only the compressor, condenser & evaporator remained. This was done *very* carefully so that the gas remained in the pipes and the system operational. I then built a plywood chest type box and insulated it with styrofoam packing sheets to a thickness of 75mm, including the hinged lid. This contraption has just the evaporator plate routed to the inside while the compressor etc sits on a low shelf outside, next to the fridge. It works very well as a drinks fridge in the shed, running only for 3 min or so every hour on average. Klaus |
||||
| Page 2 of 2 |
|||||
 Print this page |
