Here’s a really cool idea

6 09 2009

It’s funny how things work out sometimes. I’ve been meaning to do this for years…. It’s either been too poor, too busy, too many other things to do. Last year we switched to another power supplier, Integral Energy. To cut to the chase, because absolutely nobody, and I mean absolutely nobody, in the electricity industry is trained to take calls from people who sell solar power to the grid, we were basically conned into switching under the premise that we would be better off under Integral’s tariff regimes. The people who made these promises had possibly never even seen a solar array tied to the grid…

After six months we got a bill…. and zero credit for the substantial amount of energy we exported to the grid. After hours on the phone and emails back and forth we eventually did get a whole nine months rebated, but the next three was, again, not credited.

So I thought, right, they want to play silly buggers, so can I. And I disconnected from the grid, running the house from the batteries we have as backups for the occasional blackouts. At the same time all this happened, our old fridge, which I knew was on the blink, finally gave up the ghost, consuming vast amounts of energy which at night was thrashing the batteries. I woke up one morning to find them flat, which was OK (sort of – it’s a sure way of shortening battery life) because as soon as the sun was strong enough they were quickly recharged. The problem of course is that we could not continue using this fridge as long as we were relying on the batteries, and it had to be replaced.

This is not my idea, I lifted it straight off the internet. If you run a freezer, especially a chest freezer, as a refrigerator, then you will use considerably less energy than otherwise would be the case. Why? Well when you open the top, all the cold air stays inside the fridge for starters, and because they are designed to run far colder, their innards are better made. Plus the insulation used in freezers is often three times as thick as that in fridges. All you need to do is use a replacement thermostat to over-ride the freezer’s internal device.

I was lucky to have found such an item the week before here and now on eBay (in the US) here. thermostatIt is cheaper than any other alternative I’ve yet found, and it looked well made. Fifty bucks later, one arrived in the mail pronto.. now all I needed was a freezer to go with it.

Years ago, I’d spotted this unusual chest freezer in a shop. It had a drawer in the bottom. It’s the only one like it, as far as I know. The beauty of this design is that the top is very shallow, you don’t have to bend in half to reach the bottom for the beer! I wanted one….

As luck would have it of course, its price had gone up substantially. The cheapest I could find over the internet was $703, plus delivery. That was way more than we wanted to spend, and so we looked around to see what else was available.

The good thing about the GFC is that cash talks loudly these days. haierfreezerI found one of these beauties in a shop I didn’t even know existed, totally by chance. It was the last one they had. The asking price was $699. Less for cash. So I accosted this rather large salesman and asked him what was his best cash price (ostentatiously pulling out a wad of $50 notes from my shirt pocket!). $570 said he after typing a few strokes into his computer…. I nearly keeled over! SOLD said I. Would you believe that amount was exactly all the cash we had? Some things are just meant to happen….

I’ve got it all going now, in spite of the atrociously written instructions on how to program the controller, and when I finally get the energy consumption figures over the next week or so, I’ll update the post. Can’t wait.

UPDATE:

img_4686After 10 days usage, I’m pleased to announce that our new fridge is still working well, and that best of all it’s only used 2.5 kWhrs, or 0.25 kWhrs/day. You may be interested to know how I measure the fridge’s energy consumption…. years ago when I was doing energy audits for money, I bought myself my own kWhr meter which I rigged up with a hard wired lead to plug into a powerpoint, and which has its own powerpoint (at the back) into which you plug the appliance you wish to monitor. I broke the seals and zero the meter before using it. The temperature controller BTW clearly shows the temperature in the fridge is 3 degrees. It’s kind of neat to have a constant temperature readout…. you know instantly if something’s gone haywire!

UPDATE:

As usual, technology improves, and prices come down…..  I would now recommend this unit, which you can buy for $14.98 from China here…

This one reads to 0.1ºC, and whilst it has somewhat clearer instructions than the truly appalling ones that came with the other unit….  you’ll still have to work your way through the Chinglish wording!

Have fun….

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24 responses

8 09 2009
Dave Keenan

This is a well-written article. Thanks. But what has always stopped me from implementing this idea is that I know that single-cabinet fridge-freezers use way less energy than separate fridges and freezers of the same volumes, presumably because the shared wall minimises the surface area and therefore the losses. If I convert a freezer to a fridge then I’m forced to have a separate freezer and I figure what I gain on the swings I’ll probably just lose on the roundabouts. I’d be happy to be proved wrong. Do you have a separate (unmodified) freezer as well? Will you be measuring the combined consumption of fridge and freezer?

8 09 2009
Dave Keenan

It looks like you’ve used a Haier HFM185D. I can’t argue with the convenience of the drawer, but if your aim is energy efficiency wouldn’t it have been better to start with a more efficient freezer? On http://www.energyrating.gov.au I find that out of the 185 chest freezers sold in Australia, it comes second-last. Only 2.5 stars.

8 09 2009
mikestasse

Thanks for the comments Dave…. yes, we do have a separate freezer. I’ve measured its consumption at ~0.7 kWhrs/day, so between them that’s a grand total of 1.0 kWhrs/day, or 365 kWhrs/yr, which is way less than the best fridge/freezer units I’ve seen which are rated ~500kWhrs/yr.

To be honest, the star rating has be baffled. We saw, while shopping around, freezers with five stars that used MORE energy (according to the sticker) and at which I did a double take, asked the salespersons (who know nothing) what gives, and could not get any reasonable explanations. They were larger, but only marginally so, and in my opinion not large enough to warrant the doubling of the rating. I prefer to go by the energy usage than the star rating…… and we certainly do not need a large unit now we grow most of our food here and eat fresh most of the time.

I’m not convinced the drawer is an inefficient weakness of the design, because the body of the drawer itself is inside the same thickness insulated cabinet, and so is the drawer front. Plus it’s only cooled by the element which cools the bottom of the top section. So even when you open the drawer, unless you open it for a long time, the coolth would tend to stay inside the drawer.

8 09 2009
Dave Keenan

That’s good Mike. When I compare your two-cabinet total to the 300 litre to 350 litre 2-door fridge/freezers listed on http://www.energyrating.gov.au I find it doesn’t use less than the best. But it is as good as the best. So you do have a 5 star setup.

8 09 2009
mikestasse

I checked out your link to energy rating, and I found the Liebherr fridges are slightly better for the size, but they cost THOUSANDS…. a link I went to to compare fridge prices listed Liebherrs at between four and thirteen thousand dollars! That is WAY out of our league!

I would have more confidence in optimism if the optimists lived wisely!

A pessimist is a well informed optimist!

http://www.greenhousedesign.green.net.au

8 09 2009
Dave Keenan

Yeah. Those Liebherr prices are ridiculous. The Whirlpool 350 litre might be a more reasonable comparison. It only uses 7% more energy than your setup and should be around $900. Although the Whirlpool 350 litre only gives you an 80 litre freezer compartment, so maybe the Fisher & Paykel 329 litre with its 97 litre freezer is a fairer comparison. It should cost around $900 too and uses 12% more energy than your setup. But given that you already had a separate freezer, what you did made good sense.

9 07 2010
David

Great information, plant to do the same thing too (read about it on http://mtbest.net/freezer-to-fridge-thermostat.html but your solution is much cheaper!). Your freezer seems to run on 240V and not 12V – do you use an inverter from your battery bank?

I read that this caused a big loss of power instead of using 12V straight away due to the inefficient step-up required? ?

17 08 2012
mikestasse

Our house is plugged into the grid, everything here is 240V. In the event of a blackout, the energy in the batteries is converted to 240V AC by the same inverter that put it there in the first place, and feeds the grid when it’s not dead (which is 99.9% of the time!)

23 09 2011
Hugh

We have used this system for quite a long time – with a SunDanzer SDR225 freezer (roughly equivalent to the Swedish unit – whose name escapes me at the moment) – 24V DC – we have two – one as a freezer and one modified to be a fridge. They both use about 300 WH per day. A Fisher and Paykel 260 litre freezer with the same modification (240V) – uses 500WH per day (it is our ‘storage chiller – as we are a long way from supermarkets!)
Our modifications are to keep the sensor in a 250 ml drink bottle half full of water to even out temperature fluctuations – and reduce cycling.The 250 litre unit has a DC fan (more difficult in the Sun Danzers – as they are 24V). For the SunDanzer we use the DC supply to operate the contoller (an AKO 1560) – a simple enough wiring job (needs a 12V regulator – for 24V systems).

16 04 2012
Darren (Green Change)

Great write-up, Mike. I’ve built one as well – http://green-change.com/2009/05/23/chest-fridge-conversion/.

Mine is back running as a freezer at the moment, since we killed our pigs and had lots of meat to store! Hopefully soon it’ll be back in fridge mode.

Hugh’s tip about putting the sensor in a drink bottle is a great one – will have to try that myself.

14 02 2013
best rated refrigerators

A properly working Refrigerator is one of the most important appliances in any home. Regardless of where you live, you need a refrigerator to store your food and drinks.

14 02 2013
mikestasse

Whilst this is interesting info, it’s all American based, and I don’t recognise one single unit as being available in Australia…… but I published this comment for all the US readers who come here. I doubt any of them come close to what I’ve achieved with our fridge anyways….

16 02 2013
Earlene

Hey there! I know this is sort of off-topic but I needed to ask.
Does building a well-established website like yours take a large amount of work?

I’m brand new to writing a blog however I do write in my diary daily. I’d like to start
a blog so I can share my personal experience and feelings online.
Please let me know if you have any ideas or tips for new
aspiring bloggers. Thankyou!

16 02 2013
mikestasse

Hi…… the “well established” bit is only due to the fact this blog is almost five years old, don’t forget…

The short answer is no. Blogging spaces like WordPress give you templates to choose from, with loads of options to personalise your website. How much work you put into it is up to you; how often you write, whether you need to do research (I often do – but mainly because of the topics I write about), and how much media you want to upload – like photos and videos. There’s a bit of a learning curve on using this facility, but start small and you’ll soon get the hang of it.

Hood luck…..

Mike

18 04 2013
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18 04 2013
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28 04 2013
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30 09 2013
Bruce Derkenne

Great article. Thanks.

17 10 2013
Why our next projet is off-grid | Damn the Matrix

[…] unpleasant odours, and of course no lights apart from candles and torches….  Luckily for us, our fridges are so efficient that when the power came back on, the main fridge didn’t even cut in!  Imagine what might […]

12 10 2016
Shane Davis

Hi. Just wondering if after a couple of years you are still using this 2 drawer system and how is it working ? Any issues ? Does the bottom drawer get as cold as the top drawer etc . Would be interested in any evaluations you have made now. Cheers

12 10 2016
mikestasse

Unfortunately, we sold the house with the freedge in it, and that freezer combo is no longer made…. great pity, we LOVED IT!

7 12 2016
goshenw

Hi, I just managed to buy exactly the same freezer as in this article (used, for just $120)! Just about to buy the temp controller; but wanted to ask if you why (if at all) it’s better to buy the ‘hard-wired’ temp controller you linked to, vs the one where you can just ‘plug the power socket into’ – or if they are much the same thing. Thanks!

8 12 2016
mikestasse

Well done! I wish I could get another……

I’m not familiar with the ‘plug the power socket into’ unit. Can you give us a link? Anything that doesn’t need wiring up is a bonus, especially for those of us that aren’t capable of doing this ourselves….

8 12 2016
goshenw

It’s much the same (although dearer); similar ones sell for $69 from AU dealers; but you just plug the power-socket in.
http://www.ebay.com.au/itm/Digital-Thermostat-Home-Brewing-Temperature-Controller-Heating-Cooling-AU-Plug/151658503321

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