Updated: Electronic Refrigerator Thermostat

[BT Humble]

Well, I constructed the built-in-a-box prototype, and ran it over the weekend (see here for the original article).  It works just fine, and maintains a nice constant 4 degrees C inside[1].

Unfortunately the poor worn-out freezer that I started with is showing its age, and consumes about 750Wh of electricity per 24 hours.  It also takes about 2 hours to get down to 4C from a 30C starting temperature. I wasn't really expecting much better, given that it's about 25 years old and has already been thrown away once! ;-)

I'm intending to give it another try with a couple of computer power supply fans in the compressor bay, some heatsinking glued to the hot points on the outside of the case[2], and the inside at least half full of bottles of water.  So far I've invested a total of about $15 in it[3], so it's been good cheap fun. ;-)

BTH

[1] It was 35-40 degrees C outside!

[2] It's one of those chest freezers that have the coils pressed up against the inside of the metal cabinet.

[3] Including about $2 worth of electricity)

[zap]

Pretty neat BTH, glad it's working for ya. Have you ever had the refrigerant charge checked? That could bring that 750Wh down if the charge is out of whack.

Good work!

[Old F]

Sharp bit of work there BT

No doubt  a newer one would be better. But just think how much power it used as a freezer.

I have my eye on  a used small apartment size freezer to tinker with.  

Keep haveing fun.

Old F

[BT Humble]

I have my eye on  a used small apartment size freezer to tinker with.  

Keep haveing fun.

A freezer the size of a small apartment?  How could that be anything BUT fun! ;-)

BTH

[Old F]

OOps

 A freezer for a small apartment about 10 cubic foot : )

Old F

[ghurd]

About #2, Could that part of the case be loosened and brought a bit away from the main case? Maybe the coils and case could get a little air flow on both sides.

Stray thought.

G-

[Aelric]

i remember once reading an article about a vent that was behind the coils on a fridge would allow in winter time for the coils to get some outside air so they didn't have to work so hard.  Could be closed off in the winter time.   Might be an idea if it is possible, since you have 35 degree weather outside :-)  Keep us posted how this conversion works.  Great idea and might have to try it myself one day.

[wpowokal]

BTH this months Silicon Chip has a project on a PICAX powered thermostat & digital display.

allan down under

[BT Humble]

Might be an idea if it is possible, since you have 35 degree weather outside :-)  

Smart guy - I know you know that I meant 35C/95F. ;-)

BTH

[BT Humble]

BTH this months Silicon Chip has a project on a PICAX powered thermostat & digital display.

This one?

http://www.siliconchip.com.au/cms/A_105744/article.html

That's pretty serious overkill for my needs! ;-)

BTH

[Aelric]

LOL sorry didn't catch celsius, so used to seeing Farenheit I assumed that by default LOL.  its getting down into the 30's farenheit here at night in Oklahoma.  anyway still would like to hear more about you're design and how it works.  One article I read mentioned they had arcing taking place because the thermostat wasn't rated for the kind of power switching they were doing, he later rigged up a more suitable switch.

[ghurd]

I'll send you some snow in exchange for a warm front. 32=32 in my book!

G-

[wpowokal]

Er no Feb actually. Not suitable for you altimate project but maybe in the proving stage.

Sorry I spoke.

Allan.

[BT Humble]

Er no Feb actually. Not suitable for you altimate project but maybe in the proving stage.

Sorry I spoke.

Sorry if I came across as harsh - I put the smiley there to show otherwise. ;-)

(Looking for the February edition now...)

BTH