Controlling Both Fridge & Freezer

[fifis101]

Hey everyone, I picked up a free fridge on marketplace 2 days ago that was supposed to be working but turns out that's not the case. It looks like someone beat me to it & took out the thermostat & other bits.
So to get it going I bridged out the thermostat terminals & controlled the temp with a InkBird temp controller. The freezer got cold but not the fridge because the fan wasn't working.
Next I directly hooked up the fan so it would work when the compressor ran, still being controlled by the InkBird. I found that the fridge worked really well but the freezer not as well.
This morning I blocked off half the vent into the fridge so that more cooling will stay in the freezer.
The main question I'd like to ask is what's everyone's thoughts on using two STC-1000 for the fridge & freezer? One could control the compressor & the other to control the fan to cool the fridge. If the fridge needs to cool down, the fan kicks in, if that warms up the freezer then the compressor kicks in.

 

[Malted Mick]

Not a refrigeration expert, but it sounds like it will work with a bit of trial and error. Tuning in the STC temps to get it balanced may require some playing around. As a sugestion get another fan, a 240v computer fan off Flebay and wire it in to the main fan STC. This will circulate air in the fridge compartment, I assume the other fan you are talking about is pushing air out of the freezer into the fridge space.

 

[fifis101]

Not a refrigeration expert, but it sounds like it will work with a bit of trial and error. Tuning in the STC temps to get it balanced may require some playing around. As a sugestion get another fan, a 240v computer fan off Flebay and wire it in to the main fan STC. This will circulate air in the fridge compartment, I assume the other fan you are talking about is pushing air out of the freezer into the fridge space.

Yes the fan is in the freezer space & moves air from the freezer to the fridge. It blows a fair bit out of the vent into the fridge space (which is why I have blocked off half of it) so I probably don't need another fan. The backing plate at the back of the fridge was removed too & it's just an open vent hole, so I assume there's less resistance than there was before.
The main reason I'm considering making this effort is that it's actually quite a good fridge & it's a bottom mount which I like because the fridge space has a flat bottom & not the big block that the compressor normally makes in the bottom of a regular fridge.

 

[duncbrewer]

My fridge freezer has a fan in the top freezer. Small hole 10mm into the fridge.
Fridge is cooled by a back plate that gets cold. Mine was " broken " in that it would only get cold and not stop so freezing temps possible in the fridge. Fitted STC and that turns it all on and off and works well. Are you sure that yours isn't missing that chilling bit at the back of the fridge?
How big is the hole from the freezer?
For my keg fridge that is a commercial upright fridge and that had a broken fan, cost ridiculous to replace that, I made new fans out of PC fans they run on 12 V and so I just routed a transformer supply to them. The fans are powered all the time, and the compressor goes on and off as dictated by thermostat.

 

[fifis101]

My fridge freezer has a fan in the top freezer. Small hole 10mm into the fridge.
Fridge is cooled by a back plate that gets cold. Mine was " broken " in that it would only get cold and not stop so freezing temps possible in the fridge. Fitted STC and that turns it all on and off and works well. Are you sure that yours isn't missing that chilling bit at the back of the fridge?
How big is the hole from the freezer?
For my keg fridge that is a commercial upright fridge and that had a broken fan, cost ridiculous to replace that, I made new fans out of PC fans they run on 12 V and so I just routed a transformer supply to them. The fans are powered all the time, and the compressor goes on and off as dictated by thermostat.

I'm pretty sure it's not missing a chilling plate in the fridge area. I've seen the schematics too and it wasn't on there. The hole is about a 20x120mm slot and a fair amount of cold air comes out of it. I'm assuming this is the only cooling for the fridge space. I've got to play with the fan direction too. Air seems to come out with both direction but more with one than the other, so maybe I had it around the wrong way before.

 

[duncbrewer]

That can happen with those fans, what about enlarging that hole? and put the fan so it sucks from the freezer into the fridge?

 

[fifis101]

That is what it does but it's mounted in the freezer and blows cold air into the fridge. The fan direction I first had it set on was blowing a lot of air into the fridge and was able to cool it down really quickly to 4deg but seemed to be taking too much cold from the freezer or not running long eneough to cool the freezer down (freezer was only -4deg). This morning I changed the fan direction which is slowed down the air flow into the fridge, so I'm hoping when I get home it's this arvo it's sitting at temps more like it should be. I will update.

Running it without a fan gets the freezer well cold enough. So hopefully if I control the fan only to cool the fridge this should work well.

 

[duncbrewer]

Ahh I was thinking about a fan in fridge as well.

 

[Malted Mick]

Ahh I was thinking about a fan in fridge as well.

One of these is the go! AC 220V~240V Metal Cooling Fan 8025S 80x80x25mm 50/60Hz 0.1A CPU Computer Fan A0 | eBay
Prevents dead spots and different temperature zones in the fridge space.

 

[duncbrewer]

My PC fans I picked up from salvage shop for 50c each and used an old games console transformer to run it.
I have made a portable fan out of a 5 V pc fan and this runs off some 1.5 volt batteries in parallel to make 6 V.
Not so good in the fridge when cold as the batteries don't like that!

 

[fifis101]

Yeah nice but I think you mean you set the batteries up in series to get the 6V. Series increases the voltage, parallel increases the capacity.

 

[duncbrewer]

You are right the batteries add up in series ie get longer, wheras in parallel they are all at same height.

 

[fifis101]

That's a clever way to remember it!

 

[duncbrewer]

Yes but didn't work for me for my original answer, but it was how someone explained it to me once.

 

[fifis101]

I just came across the STC-3008. Looks like the perfect thing for this situation. It has two temperature probes & you can use both for either heating or cooling. Plus it's the same price as the STC-1000.