Aircon / Refrigeration Gurus

[mfeighan]

Firstly a bit of background info. My lovely wife organised getting me 2 conical fermenters for my 30th. Downside is they dont fit in my fridge/freezer pair. The fermenters costing more than the fridges etc i dont want to chop 1 leg off the fermenters so it will just fit over the compressor hump. I looked around and could not find a fridge big enough so i built a fermentation chamber which has been working well so far at keeping temperatures at ale and just at lager temps. It isn't summer yet so i am anticipating problems with my current setup.

I saw https://byo.com/stories/issue/item/1877-build-your-own-glycol-fermenter and snatched up a portable aircon off gumtree for $100. Tested it all worked well so i started pulling it apart...

I realise it wont be as simple as those box air-conditioners as they are cooling only and the one i have is reverse cycle... oops

I already have an old esky, 12v submersible pumps, copper coil for wrapping the fermenter in and a stack of glycol. A spare stc1000 and a generic temp controller (cool only) that i got like 5yrs ago from CB. They both have compressor delay so i was thinking of setting to -10 with a 9 deg swing hoping it would cycle on and off less.

My question(s) before I butcher the aircon unit more are:

1) can I bypass the digital controller and hook up the fan/compressor directly

2) how can i set it to cool only?

I have some photos of the unit and after reading http://www.homebrewtalk.com/f51/new-brewery-texas-252146/index2.html he said something about the just hooking up to the capacitor which i am ok with but assume there is a way to switch the compressor from heating to cooling mode so i had another homebrew and started typing

The board

The compressor

The Capacitor



Also if anyone savvy enough North of the river (perth) wants to come over and rewire it for some brews let me know

 

[dent]

The following remarks are from an electrical perspective - I'm not a fridgy.

You could run the compressor directly - the capacitor is for starting, depending on the type of compressor it can be as simple as connecting the capacitor in series with the motor -- or there may be separate start and run connections to the motor - with that you connect the capacitor first to the starting winding, then power to the run after the motor gets cranking. So then you might need a timer. Often there is a circuit diagram in the unit if you go digging.

There may a reversing solenoid valve that controls the direction of the refrigerant flow. So you'd want that in the right direction too - you might be lucky and it will default to cooling anyhow.

 

[michaeld16]

Question 1 yes + 1 what dent said just make sure fans are powered on at same time as compressor

Question 2 yes the reversing valve solenoid coil is energized for heating and de energized for cooling so on the board somewhere will be a plug marked rev valve or 4 way valve just disconnect that and the coil will not energize forcing it to run cooling only.

 

[mfeighan]

cheers guys, will have a bit more of a look tonight. I looked at the control board and worst case is i can use an arduino to control it which is more in the field i understand.

 

[Ducatiboy stu]

Be warned that an air-con unit will ice up

 

[mfeighan]

Will it ice up in a bath of glycol?

 

[Ducatiboy stu]

probably not...missed that bit

 

[mfeighan]

Thanks for your input Dent and Michaeld

I think i have isolated the starting relay and this valve/solenoid you speak of. Is it right to say if i disconnect the wire to this valve and say set it to heating mode the radiators will heat and chill exactly the same as if it was on cooling? Or vice versa if it was set to be on for cooling?

 

[dent]

Sounds about right to me - with the solenoid disconnected it will be in the same mode (hopefully cooling) no matter what the setting is. It should run OK unless it has some pressure switches in there that it could use to tell that the refrigerant is going backwards to what it expects, or some temperature sensors on the evaporator/condenser - unless you're powering the compressor directly, of course, then it won't matter.

 

[michaeld16]

With the valve disconnected the refrigerant can only go the cooling way pressure switches won't worry it as for the sensors it just means the fan won't want to run if set to heating mode but won't matter if your doin the glycol thing

 

[woodwormm]

MIkey, feel free to send your wife this way, I think she's a gem!

 

[mfeighan]

Cheers for the help fellas hooked it up last night and its working as I expected. Bypassed all controls so I can set the fridge controller to it. Will tidy up wiring later