Author Topic: Freezer to Fridge conversion (Read 13611 times)

geoffd · « **on:** March 01, 2008, 03:14:27 PM »

Spurred on by some of the conversion threads and the fact that our Fridge/Freezer combi went phut I decided to convert a chest freezer to a fridge.

I wad going to buy an electrical controller when I saw on eBay a mechanical thermostat controller. This I think is used in heating / cooler systems and consists of a thin copper tube connected to a thermostat.

I put this in a plastic box and fixed it to the back of the freezer. I cut an extension cable in two, wired the plug half as the input, and the socket half as the output. It was a simple matter of threading then cooper tube into the freezer, plugging the freezer into the socket and the other end of the wire into the wall and away we went.

For the first few days I monitored the power consumption with a 'Kill-a-watt' type meter and is uses a maximum of 160 watts in 24 hours, a great improvement of 1200+ watts for the original combi. The next plan is to buy an efficient freezer.

The Thermostat

The box wired up

The sensor stuck down with duct tape.

The completed fridge.

ghurd · « **Reply #1 on:** March 01, 2008, 09:20:15 AM »

Nice work.

I'd be a bit concerned about the thermostat running the motor directly.

Might want the thermostat running a large heavy duty relay.

Are there any HP ratings on the thermostat?

G-

commanda · « **Reply #2 on:** March 01, 2008, 03:52:47 PM »

I presume the watts, rather than wattHrs, was a simple typo.

I recently tested my domestic fridge/freezer combo and got 1260 wattHrs per day.

That thermostat has an RS part number on it. You can look up the full specs on the web.

Their Australian website is:

http://www.rsaustralia.com

I'd look it up for you, but can't quite read the numbers off your photo.

Amanda

fungus · « **Reply #3 on:** March 01, 2008, 04:51:36 PM »

http://www.rsaustralia.com/cgi-bin/bv/rswww/searchBrowseAction.do?obs=sObs&name=SiteStandard&
;No=0&N=0&Ntk=I18NRSStockNumber&Ntt=250-6112&Nty=1&D=250-6112&Ntx=mode%20mat
chpartial&Dx=mode%20matchpartial&callingPage=/jsp/homePage/homePage.jsp&BV_SessionID=@@@
@1051550274.1204415449@@@@&BV_EngineID=ccciadedhgdlfllcefeceeldgkidhgm.0&cacheID=aunetscape&
amp;Nr=avl:au

There it is .. can just read the no.

dynaman · « **Reply #4 on:** March 01, 2008, 07:08:40 PM »

You might want to refigure I can guarantee it is using quite a bit more than 160 watts per day.

wdyasq · « **Reply #5 on:** March 01, 2008, 08:31:24 PM »

The one built and tested at Mt. Best drew 100wH a day.

http://mtbest.net/chest_fridge.html

Perhaps you should refigure..... or maybe he has an inefficient freezer ....

Ron

domwild · « **Reply #6 on:** March 01, 2008, 08:41:25 PM »

Well done! Saw a thermistor + relay solution in Silicon Chip, an Aussie electronics mag. From memory thermostats drive the motor directly of fridges and freezers as they have rather large contacts, but if you are concerned you could drive it via a relay.

Regards,

Volvo farmer · « **Reply #7 on:** March 01, 2008, 10:31:57 PM »

Nah,

Look at the specs on that control. It's rated at 15A at 240V. It will work fine in this application without a relay.

Quite impressive specs coming in on these chest-fridges. Maybe I'll have to build me one myself and hook the kill-a-watt to it. I still think the wife would be not-happy fishing for mayonnaise or Thousand Island amongst cans of beer and egg cartons.

geoffd · « **Reply #8 on:** March 02, 2008, 05:36:05 AM »

I checked out the thermostat before I bought it. It is rated at 15amp at 240 volt, so plenty of juice for this. I think they are used for A/C or Hot water elements.

geoffd · « **Reply #9 on:** March 02, 2008, 05:40:19 AM »

It is an inefficient freezer. It is only a class 'B' rather than a class 'A' or 'A+', but that was a trade off on price. We only paied 250 euro against 400+ euro for the more efficient.

Cheers

Geoff

MattB · « **Reply #10 on:** March 02, 2008, 08:59:57 AM »

Efficiency like that, Bob.. you can build you two of 'em. One for your keg, one for your wife :-)

wdyasq · « **Reply #11 on:** March 02, 2008, 09:04:22 AM »

Even with PV units I don't think the cost of the more efficient freezer would be worth it. 60 Watts 4 hours sun is 15 Watts additional solar panel. At $4 Watt 3 euro you could buy 30-50 Watts of PV for the difference in cost. 60Wh X 30days is 1800 Watts less than 2 kWh a month. Even where I am with $0.16kWh electricity the extra cost will not be justified.

Ron

Opera House · « **Reply #12 on:** March 02, 2008, 10:12:27 AM »

I've thought about doing this for a while. I have 150W of panels for a camp and a small Norcold 60W fridge. Thought that 80% of the time it would be able to hold its own, but every time I am left with a dead battery after two days. At 200W/H a day it might work. I would use a smart controller and dump load amps into the fridge. Better to store extra cold during the day than amps into a battery. I still don't buy all these claims. There are gains with minimal surface area of a square design and top load, but digging through a chest takes extra time going through lots of cold drinks is a constant. With luck I'll find a used one cheap at a garage sale and try again this year for a solar powered cooler.

BT Humble · « **Reply #13 on:** March 02, 2008, 02:46:19 PM »

When I tried this a couple of years ago with a real old clunker of a freezer, I maanged 750Wh per day.

http://www.fieldlines.com/story/2006/1/29/215131/553

Bear in mind, this was a freezer that had been dumped, which took several hours to get down to zero celsius.

BTH

Gog · « **Reply #14 on:** March 03, 2008, 02:30:04 AM »

Would replacing the freezer thermostat with a fridge one do the same job as the external thermostat,

( I know it would be more fiddly )

Or am I missing something.

Cheers

Keith

BT Humble · « **Reply #15 on:** March 03, 2008, 03:51:57 AM »

Would replacing the freezer thermostat with a fridge one do the same job as the external thermostat,

( I know it would be more fiddly )

Or am I missing something.

I don't see why that wouldn't work. The major benefit of using an "external" thermostat is that you don't modify the freezer, and to use it as a freezer again you just have to plug it into a power outlet as normal.

BTH

Volvo farmer · « **Reply #16 on:** March 03, 2008, 06:41:52 AM »

I see one possible problem with that. Refrigerator thermostats generally sense air temperature. Chest freezer thermostats have the sensor shoved into a long tube along the evaporator coil. While it might work, the differential for an air sensing thermostat and a surface sensing thermostat might be different. Results might be large swings in interior temperature or compressor cycling in too short of intervals.

Opera House · « **Reply #17 on:** March 03, 2008, 07:20:32 AM »

Fractional HP shaded pole fan motors have a very low efficiency. One or two small 12V .1A DC muffin fans would save quite a few watts. This would be quite useful if using a small 200-300W inverter. A simple capacitor drop diode bridge could power it on AC and provide a little power factor correctionat the same time.

ghurd · « **Reply #18 on:** March 03, 2008, 08:41:09 AM »

Very good call.

The tiny fan in my fridge says 40W and doesn't move much air.

Can someone get me the part number for that thermostat?

The links over ride my windows, claim the session timed out, try to close the window, then crash...

Vista.

:-(

G-

Volvo farmer · « **Reply #19 on:** March 03, 2008, 09:55:14 AM »

I just bought one for a customer's reach in.

White Rodgers 1609-101 will do the job. About $50-60

commanda · « **Reply #20 on:** March 03, 2008, 01:36:18 PM »

RS Stock No. 250-6112

Manufacturer ALTECNIC

Manufacturer's part number IM-TR2/540030

Quantity Price (in Aussie dollars)

(ex. GST): Each

+ $43.20
+ $39.80
+ $38.50

Amanda

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Author Topic: Freezer to Fridge conversion (Read 13611 times)