My brewing fridge without a fridge

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SANGER_A2

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Location
Petersfield, Hampshire
DISCLAIMER: I have a lot of experience of working with electronics. If you don't, probably best not to attempt this - find a friend to help you. I take no responsibility for you getting electrocuted or your house burning down if you copy anything I described here!

IMPORTANT SAFETY UPDATE: If you are planning on using a cylinder jacket with a brew belt please read post 16 as the belt will melt the plastic in the jacket if you don't put something in between them.

It is incredibly dangerous when having any kinds of liquid near electricity - especially mains. It can lead to you getting electrocuted or fires starting. The biggest danger is my setup is the 550W computer PSU. I couldn't put it in an insulated box as it needs airflow for the fan to work. I just did my best to keep liquid away from it. The STC-1000 is mounted above the setup on a strong shelve, so that is fine. The power source for the STC-1000 is above that again. There are two sources of liquid in this setup - the brew and condensation build-up from the cooling system. As for the brew, I will be turning off the power at the mains whenever I do anything with it such as putting it on or off or sampling. Also, the "stool" is incredibly strong so there is no change of it collapsing and the brew ending up on the PSU. As for condensation: there are two layers of plastic between the liquid and the top of the power supply and a layer of plastic in between the side of the PSU and the fan cooling the heatsink on the peltier in case it flings condensation out to the sides. Any gaps are filled with silicone. I also have fuses and electrical cut-outs all over the place. I built an automotive fuse-holder into the molex wire that powers the peltier so if it dies it won't fry the power supply. The power supply has a fuse in it's plug, as does the heater belt, as does the plug for the STC-100. The STC-1000 is plugged into an extension lead I mounted on the wall, which has it's own fuse and that is plugged into Masterplug RCD Plug, which will cut-out if the current overloads (these things really work - I was using a hedge-trimmer plugged into one of these and accidentally cut through the lead and the RCD cut the power immediately).

So my OH is completely illogical and won't let me buy a second hand fridge for £5-10 to control my fv temperature. So I decided to try to get the same effect without the fridge. It's nearly complete, apart from that I need to buy a hot water cylinder jacket for £10 or so to make it more efficient. I bought a cheap plastic tub from sainsburys and a couple of plug sockets and pattress boxes from Toolstation to fit an STC-1000. Pretty much everything else I needed I already had lying around - including a load of wooden bed slats for the base, a computer power supply and an old mini fridge. The stc-1000 heat sensor is held next to the fv with duct tape insulated from the outside temperature with a few layers of thin packing foam.

For heating, instead of using the usual greenhouse heater that everyone else uses inside the fridge I bought a brewing belt for under a tenner that works brilliantly and only uses 60 watts.

For the cooling I chopped up an old mini fridge I never use to get the peltier and heatsink from. You can see pictures of how I set it all up below. I've put some plastic on top of and to the side of the computer power supply to stop any condensation getting into it. The way peltiers work is they generate heat on one side of the plate and cold on the other. The cold side is transferred through a block of aluminium to the round disc of aluminium I attached using thermally conductive glue. The heat is transferred to a heatsink that is blown away by a fan. I upgraded from the cheap rubbish 80mm fan that came with the fridge to a much more powerful 120mm I had lying around. The fan works great, even after being on a whole day the heatsink doesn't get more than slightly warm. The PSU powers the fan and the peltier and the whole thing including the stc-1000 draws just 50 watts.

It heats up the ferments vessel brilliantly. Cooling is not so great due to the low power of the peltier the cold lost through the sides of the fv (which will be fixed when I buy the hot water cylinder jacket). The biggest issue of course is that I'm putting cold into the bottom of the vessel and he heat can't spread through convection, just radiation/conduction (not much I can do about that without changing the laws of physics). I can go the brew down to a few degrees below ambient at the moment, but I'm hoping that will be doubled when I get the insulation on it.

It does an okay job, but I'd much rather have a fridge using refrigerant cooling rather than a peltier! I'll have to keep nagging the wife! Space is really tight in the garage, mounting the stc-1000 on the wall above the cooling stand helped a bit.
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Thanks for all the positive comments guys. I'm mainly pleased with how little it has cost me. We had an old Ikea bed that had been going for about ten years that I just cut up and took to the dump, but the slats were still in excellent condition so I've been looking for projects to use them with such as the base for the cooler and the STC-1000 shelf. The stool thingy I built will hold my weight without even creaking. It's completely over-engineered - but as I'm messing with mains power and liquids I thought I'd better be safe rather than sorry! :) In fact, after writing that sentence, I decided to add a safety disclaimer bit to the thread!

As to an insulated cupboard, I may even have enough bed slats to build one, but I'll have to investigate cheap, easy-to access insulation options. If I did that, I'd have to move the PSU outside of the box as condensation would build up inside it. I'd probably build an enclosure on top of the box that holds the PSU and the STC-1000.
 
So could you use the four panels of the cylinder jacket as insulation for the cupboard? If you built an outer frame with the slats, put the panels on the inside then put chipboard/MDF or even cardboard inside that, so you've made a 'sandwich' if you like?
 
I got it from aliexpress for a fiver. Brand new straight from China. You get amazing deals direct from the manufacturers. I had to put on a UK plug, but I've got loads of them lying around.

I recognised that name 'aliexpress' and realised they are also the only supplier of the programmable STC-1000's straight from the manufacturer.

Well, not the only one but you have a greatly increase chance of getting the right type from here.

For more info, see here: https://github.com/matsstaff/stc1000p
 
I recognised that name 'aliexpress' and realised they are also the only supplier of the programmable STC-1000's straight from the manufacturer.

Well, not the only one but you have a greatly increase chance of getting the right type from here.

For more info, see here: https://github.com/matsstaff/stc1000p
Yeah I bought mine from Aliexpress for just £7.84. I only discovered aliexpress about a year ago and I've bought loads of stuff from there since. It's far better value than Ebay.
 
So, I eventually bought a cylinder jacket for £15 or so to make it more efficient. I don't bother putting it on until a few days after fermentation has started and the temp of the brew has dropped to 21-22c. I bought a few bungee nets on Ebay for a quid each. These are great, I had a couple already for my motorbike, but as one was knackered and I needed to buy 2 more, I just bought three new ones and made them all red to match the cylinder jacket. (Pic attached).

Incidentally, I've stopped using airlocks now. Every time I used one, either the liquid in it falls into the brew at some point, or it just boils off in no time. I'm using a blow-off tube that goes into a contained I drilled a large hole in the top for the tube and a couple of smaller holes in the top for air to escape from (pictured). I fill it mostly full with water and add a little VWP to keep it sterile (this WILL make the tubing go opaque). The idea was completely stolen & modified from this thread!

Do NOT use the brew belt with the jacket as it is!!! It will melt the plastic. I had some protective L-shaped foam edging that wasn't being used that I tape over the brew belt. This helps keep the heat from the brew-belt going towards the brew and stops it melting the plastic in the cylinder jacket. I've used it on two brews since with no issues.

With the cylinder jacket, I can get it down to about 13-15c in three days. Not very good, but the peltier, fan and PSU are only drawing about 60 watts, so it's hardly a high powered device! I really need to just persuade my wife to let me buy a cheap fridge/freezer! Or possibly use it with a water bath instead. The problem with the peltier system heating the bottom of the brew is that the cooler beer stays at the bottom and doesn't radiate/convect very well to the rest of the brew. If you're cooling, you should be putting the cold in at the top or at least the side so it can sink down and push the heat up to be cooled.

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This is fascinating - I've been thinking about doing something like this for a while but been unsure if it'd work at all.

How is your heatsink attached to the FV?

With my most recent BIAB batch I'm having a go at fermenting in the boiler (heavily modified Buffalo urn) for a one-vessel brew. Having a working Peltier cooling system would almost turn it into a complete worktop grain-to-bottle machine.

Your updates are much appreciated - please keep them coming if you have time!
 
This is fascinating - I've been thinking about doing something like this for a while but been unsure if it'd work at all.

How is your heatsink attached to the FV?

With my most recent BIAB batch I'm having a go at fermenting in the boiler (heavily modified Buffalo urn) for a one-vessel brew. Having a working Peltier cooling system would almost turn it into a complete worktop grain-to-bottle machine.

Your updates are much appreciated - please keep them coming if you have time!

I have a 2 month old baby so there hadn't been a huge amount of development (although I've used it a lot). The heating works brilliantly, but the cooling could be better. I've bought some bits to totally revamp the cooling system using a cpu heatsink and pump unit and a peltier that draws double the power. I won't be running the brew through the pump though: I've got a metal bin from ikea to hold water that the fv will sit in and I will heat or cool the water. I'd like to use the peltier to heat as well as cool, but can't think of a way to do it via the stc without a second pc psu. The brew belt works amazingly anyway.
 
I have a 2 month old baby so there hadn't been a huge amount of development (although I've used it a lot). The heating works brilliantly, but the cooling could be better. I've bought some bits to totally revamp the cooling system using a cpu heatsink and pump unit and a peltier that draws double the power. I won't be running the brew through the pump though: I've got a metal bin from ikea to hold water that the fv will sit in and I will heat or cool the water. I'd like to use the peltier to heat as well as cool, but can't think of a way to do it via the stc without a second pc psu. The brew belt works amazingly anyway.
So I used the new system where the peltier cooled water that the FV sat in and it worked better, but I could only get it to about 5-7 below ambient. I would say this system is only worth doing if you really 100% cannot get a fridge and you like tinkering. In the end I managed to persuade my wife to let me buy a second-hand fridge and built a standard brewing fridge with greenhouse heater and wooden shelf it. It works much better and the brew is currently cooling to 5c to help the gelatin clear the brew before bottling next week.
 
I like to see how people are able to utilise their skills and with apparent ease build something like that!
I would have just bought the fridge whether the other half liked it or not. Mine has illogical thoughts too....two feet yet 100's of shoes (probably),30 pairs of jeans,4 cats,3 dogs. You get the picture...

Cheers

Clint

...you DID get the fridge. ..Nice one. ..on my to do list.
 

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