Energy Matters Forums

[lad]

I have seen an underground cool room here in northern Tasmania. It has an "airlock" type entrance ie: one set of doors, a small room and another set of doors then the cool room. The doors are both timber with the internal doors being heavy timber (2 inch hardwood). There is no air seal on either set of doors. The walls are domed brickwork covered in a minimum of 1 meter of earth. There are no additional insulative materials used. This cool room sits at 15 degrees C all year. This is an excellent environmental solution.

I could see an additional room added to this, being insulated and having a compressor installed to give a cold store to complete the picture.

The key to its success is the thermal mass. The "roof" of the structure has grass and low vegetation and is in a bush setting.

It was very pleasant sitting in the "airlock" looking out the window, drinking home made 10 year old cherry wine.

What else could you want for......

[Tracker]

Chest freezers are always the most efficient, be they used as a freezer of a fridge.

To get things into perspective, the freezer thermostat normally has a thin tube inserted into the freezer wall.
It has just two electrical wires.
You can buy a "Drink-Fridge" version of the same thermostat, that can be be swapped as a direct replacement.

The replacement thermostat would likely set you back about $30..

The only benefit of the $150 version is that you don't have to tamper with your freezer..
.
.

[Willandra]

DC compressor units typically are more energy efficient than AC induction (240VAC) type compressors. That is, they use LESS electricity for a given transfer of BTU's.

The key element as you have sussed is insulation - the more the better. You can buy polyurethane in a spray, or in sheet form. Tel 02 9898 0751.

Eutectic is desirable for solar based systems - a eutectic fridge will reduce the battery load. For DIY try the following:-

http://www.ozefridge.com.au/System%20Details.htm

Be warned - you cannot believe all you read on the net, and especially not in forums. Also please note that to a large extent the alternative energy industry has taken over where shonky used car dealers left off....

Cheers,

Paul

[stivzor]

http://www.ozefridge.com.au/System%20Details.htm

Be warned - you cannot believe all you read on the net, and especially not in forums. Also please note that to a large extent the alternative energy industry has taken over where shonky used car dealers left off....

Thanks Paul,
that site looks like exactly what I have been looking for. Do you know what prices apply for the packages?

(ha ha - I have been on enough forums to know that you need to have any advice backed up!)

I still think my plans are feasible, although I do have to weigh up the DC/AC issue...

Stivor

[Willandra]

Thanks Paul,
that site looks like exactly what I have been looking for. Do you know what prices apply for the packages?

(ha ha - I have been on enough forums to know that you need to have any advice backed up!)

Hi Stivzor,

The eutectic units are a bit expensive, around $1500 I think, but the dollars you will save on solar panels/inverter watts going 24VDC instead of 240VAC should more than compensate.

Good luck, it is very satisfying when you design your own system - and a LOT cheaper!

FWIW, I have set up four solar systems over the years, and I have never applied for the grant. It worked out cheaper to do it myself without the grant than to get in a "professional" and get the grant.

Cheers,

Paul

[GeoffHammond]

I'm currently running a chest freezer with an external thermostat that I built myself, but am also going to use two fridge controllers to control the freezer temp of my Kiwi fridge/freezer's freezer section to around 6-8degC and the fridge section to around 17degC. The latter is happening already. You can buy such controllers from homebrewing suppliers or from the big auction site in various states of construction.

Several home brewers have built big cool-rooms out of foam panels, etc and installed a small 240V window-mount air conditioner with its thermostat bypassed/replaced with one of the above-mentioned units.

Amid all the nay-sayers, many of these things seem to last for quite some time. Here's one:

http://www.mrmalty.com/brewstuff.php

[GeoffHammond]

...and here's a couple more:

http://franklinbrew.org/members/sj/walkin.html

http://www.homebrewtalk.com/f51/my-late ... ler-11440/

So, it's certainly doable. The thing that stands out for me is to ensure you insulate the room to double what you think is excessive then a bit more to ensure you don't use too much energy keeping it cool, then find a way to combat excessive moisture and ensure you don't build a mould-farm...

[howesij]

Hi

Have a look at http://cgi.ebay.com.au/12v-Fridge-Freezer-258Lt-CHEST-FREEZER_W0QQitemZ300398798492QQcmdZViewItemQQptZAU_Sport_Camping_Hiking_Food_Storage?hash=item45f129e69c

They are selling 258 lt 12v/24 freezers and upright fridge freezers

***Specifications***
Power Demand 7.5amp +/- 10%
Power Supply: DC 12V/24V
Power Rating: 90W on duty cycle
Capacity: 258lt freezer
Weight : 55kg
Fridge Dimensions : 1245(HL) x 665(D) x905(H) mm
Compressor : R134a Reciprocating Compressor
Power Cord Length: 1.8mt


***Specifications***
Power Demand 7.5amp +/- 10%
Power Supply: DC 12V/24V
Power Rating: 90W on duty cycle
Capacity: 210 liter ie. 142lt fridge 58lt freezer
Weight : 50kg
Fridge Dimensions : 1600(H) x 520(W) x550(D) mm
Compressor : R134a Reciprocating Compressor
Power Cord Length: 1.8mt