Not-a-kegerator

[The-Engineer-That-Brews]

Just to show you don't necessarily need a secondhand fridge to cool your beer down, here's a photo of the @TETB chiller cabinet - based on a modified and re-purposed portable A/C unit (£35 off flea-bay) and a box made from marine ply and expanded polystyrene building insulation.
Gets down to -2ºc in about 5 mins, and it's got space for 8 full-sized Cornies so it might even keep up with @Hazelwood Brewery

 

[Clint]

Interesting...Mrs Clint has one of those air con things in her shop..but it might be missed!

 

[The-Engineer-That-Brews]

Interesting...Mrs Clint has one of those air con things in her shop..but it might be missed!

I found it pretty useless as an A/C - but flipping brilliant as a cheap way of buying a cheap 12,000 BTU refrigeration machine - once I'd bypassed the thermostat that limited it to 16ºC min (pah...!)
This is an old Homebase one, also sold by Wickes - they can be picked up for a song online, especially in the Winter...

 

[jayk34]

What is the electricity usage like with that AC unit ?

 

[The-Engineer-That-Brews]

What is the electricity usage like with that AC unit ?

Well the quick answer is that it takes 6.2 Amps (cooling), which ain't bad.
The longer answer is that it depends how often it comes on - which in turn depends on how well insulated the box is, and the temperature difference versus ambient.
At the moment this one comes on for about a minute once every 40min; more when I've recently put a fresh keg in there of course...

 

[Hazelwood Brewery]

Just to show you don't necessarily need a secondhand fridge to cool your beer down, here's a photo of the @TETB chiller cabinet - based on a modified and re-purposed portable A/C unit (£35 off flea-bay) and a box made from marine ply and expanded polystyrene building insulation.
Gets down to -2ºc in about 5 mins, and it's got space for 8 full-sized Cornies so it might even keep up with @Hazelwood Brewery

View attachment 49833

Great job! My brew-shed is great but is completely over-engineered because I’m a project junkie!

 

[jayk34]

Nice idea, looks the part.

Was trying to get an idea of this would be an option for a bigger fermenting cabinet for my garage. So from my calculations going by the label would mean for every hour the unit is on during fermentation, would cost 1.4 units of electricity ?

 

[Leon103]

Perhaps this my next step if I have another fridge failure in the future. You better do a step by step guide of all the mods.

 

[DocAnna]

Really interesting idea to use an air conditioning unit this way - we have a dehumidifier in the back shed, wondering whether it could be made to cool as well. Your cabinet here is brilliant in terms of capacity - your own beer cellar!

 

[The-Engineer-That-Brews]

Perhaps this my next step if I have another fridge failure in the future. You better do a step by step guide of all the mods.

First, a couple of important notes:

This modification basically cons the A/C into thinking that the temperature in the room it's trying to chill is always 'too high'. That means you, or more precisely your control gear, become responsible for switching it on and off as appropriate without running it too long or turning your beer into a lump of solid ice.

This process of controlling the A/C is, unfortunately, slightly more complex than just plugging your Ferm-fridge into an Inkbird - because the A/C unit does not automatically go into 'cooling' mode when it first powers on. You may be able to make it do so by taping the buttons down (or some such - the circuitry isn't exactly complicated) but I didn't go that route: instead I use a microcontroller to re-create the Infra-Red signals from the unit's own remote control handset... I'm happy to share the details of that, but it's outside the scope of this quick how-to.

Remember also that an A/C is not a 'magic cooling machine': it, like every other machine in the universe, has to kick out more heat than 'cold'. So whilst the air flowing across the evaporator gets nice and frosty, the air flowing across the condenser gets hot - so you have to route the two airflows separately with some kind of ductwork. You can see roughly how I did that in the piccy at the top of this thread - but the details will have to suit your cabinet design.

OK so you still want to do it - fine... but unplug it first (!!) and proceed at your own risk :-)

Step 1: remove the rear cowling

Basically take all the screws out, starting with the side handles, and then manoeuvre it off - you may be able to skip this step (see step 2).

Step 2: identify the air-intake thermistor

It's this part: a little black bead attached to a plastic clip sitting against the evaporator... you MAY be able to reach it without removing the rear cowling if you slide the air intake filter out.

Step 3: replace the thermistor with a fixed resistor

Doing this will mean that the unit thinks the room it's trying to cool down is always too warm.

Carefully cut the wires a centimetre or so from the thermistor, and remove it.

If at all possible, measure the thermistor using a multimeter to make sure that you replace it with an appropriate value of resistor. Mine was 12k Ohms at room temp, and the resistance fell as I warmed it up - but yours may be different.

Solder an appropriate resistor in place of the thermistor bead, and then carefully and securely insulate any bare wires.

4. Reassemble and test

When you switch the unit into 'cooling' mode, the compressor should now kick in straight away regardless of the target temperature setting, and the unit will carry on cooling for as long as you leave it running (so don't just leave it on, because it will probably freeze up/overheat/catch fire).

 

[Deadhead]

Fantastic!

 

[Hanglow]

Yeah great effort. If only I was semi competent at DIY I might be tempted to do something similar

 

[user 18729]

Just to show you don't necessarily need a secondhand fridge to cool your beer down, here's a photo of the @TETB chiller cabinet - based on a modified and re-purposed portable A/C unit (£35 off flea-bay) and a box made from marine ply and expanded polystyrene building insulation.
Gets down to -2ºc in about 5 mins, and it's got space for 8 full-sized Cornies so it might even keep up with @Hazelwood Brewery

View attachment 49833

Love this

 

[The-Engineer-That-Brews]

Nice idea, looks the part.

Was trying to get an idea of this would be an option for a bigger fermenting cabinet for my garage. So from my calculations going by the label would mean for every hour the unit is on during fermentation, would cost 1.4 units of electricity ?

Yes that's correct - 1.4 kiloWatt hours for every hour that the chiller is actually running. That is a fair bit more than a domestic fridge (about 150W) but on the other hand the fridge might be running more like 30 mins in every hour.

It's difficult to say how many hours per day the chiller would run during a fermentation: IIRC while I was doing the Pilsner recently (10ºc fermentation) it was going for about a minute every quarter of an hour at first, and then that dropped off to maybe a minute every half hour once it had chilled down?

If you are sensitive to the running cost in terms of electricity then it really would be worth going to town on the insulation on the cabinet. I've used 20mm ply, lined out with Wickes 40mm expanded polystyrene and sealed with decorators caulk... but if I were doing it again I might use the Kingspan stuff because I suspect the performance is quite a bit better...

 

[Hazelwood Brewery]

If you are sensitive to the running cost in terms of electricity then it really would be worth going to town on the insulation on the cabinet. I've used 20mm ply, lined out with Wickes 40mm expanded polystyrene and sealed with decorators caulk... but if I were doing it again I might use the Kingspan stuff because I suspect the performance is quite a bit better...

I’d agree. If I were making one of these cabinets I’d use 100mm Kingspan all round - including the base and then put ply on top of that as your new floor. Make sure you cut everything accurately and square and that you tape up every edge to prevent any warm/cold air squeezing through the gaps. Give thought to how you will seal the door(s) because these will be your biggest issue. Also remember to insulate the door(s) too - you can fit ply all round a piece of Kingspan as the door for example.

 

[The-Engineer-That-Brews]

Give thought to how you will seal the door(s) because these will be your biggest issue. Also remember to insulate the door(s) too - you can fit ply all round a piece of Kingspan as the door for example.

Totally agree - the door is the tricky bit. I used a sheet of 10mm ply with an inset slab of insulation that's a tight fit to the inner dimensions of the 'ole; then two lines of foam draught excluder tape around the edge, and the whole thing's clamped up tight with flip-over catches around the edge. I still reckon that's where most of the heat loss is though...

 

[The-Engineer-That-Brews]

One thing to be aware of is that the cost of the materials to make the cabinet really add up. I don't reckon I got much change out of £150, and it would have been a darn sight more if I'd used the Kingspan.
A good starting point might be to track down an old (defunct) chest freezer, and use that for the cabinet (there seems to be a ready supply of those left in lay-bys...) Come to think of it, pay a bit more and get yourself one that's still working...

Bizarrely, the online listings for chest freezers seem to be a bit 'coy' on the subject of the internal dimensions... is anyone using these with full-height corny's (and Inkbird or similar) ?

 

[Kev Mort]

Yes I have one, I bought it new from Currys and added a wood collar. I can get 4 of the tall kegs (19 liters) in it and 1 shorter but fatter keg (again 19 liters) on top of the motor/compressor hump. You could make the collar a little taller and get 5 tall slim kegs in. It's a tight squeeze and sometimes a bit of juggling is needed to get a keg out that is at the back of the unit, it's something to bear in mind that a full 19 liter keg is heavy especially when it has to be lifted clear of the collar as well so this set up might not suit everbody.

 

[The-Engineer-That-Brews]

Yes I have one, I bought it new from Currys and added a wood collar. I can get 4 of the tall kegs (19 liters) in it and 1 shorter but fatter keg (again 19 liters) on top of the motor/compressor hump. You could make the collar a little taller and get 5 tall slim kegs in. It's a tight squeeze and sometimes a bit of juggling is needed to get a keg out that is at the back of the unit, it's something to bear in mind that a full 19 liter keg is heavy especially when it has to be lifted clear of the collar as well so this set up might not suit everbody.

Most ingenious - and nice work there
Good point about the lifting in and out thing... I think I'd maybe see if I could fit a rope and pulley arrangement above - or possibly fill them in place?

 

[foxbat]

Most ingenious - and nice work there
Good point about the lifting in and out thing... I think I'd maybe see if I could fit a rope and pulley arrangement above - or possibly fill them in place?

I fill mine in-place after putting my back out lifting a full keg in. My fermentation fridge is at a suitable height to make it work but I've also got a Switzer scissor lift for moving the full FV around and up and down.