View Full Version : Guidance on a first foray...

09-08-2005, 11:17 AM
This is my first post here, and I'm hoping this isn't too far outside the scope of the forums, that this is an appropriate category, etc. If it is not, please let me know.

After many, many hours of searching tonight, this is the first time I feel I've found useful information on the subject of designing a refrigeration system. This is well outside my expertiese, as I'm a computer guy, but it seems I should be able to implement something.

One of my hobbies is home-brewing beer. Ideally, I'd like to be able to refrigerate kegs of beer, as well as be able to transfer beer (direct draw) from the kegs to outside of the refrigerator (co2 pressurized keg). I'm expecting to deal with kegs that are either a) 8-9" (20-23cm) in diamater and 22-25" (56-63.5cm) high, or b) 17" (43cm) in diameter and 15-23" (38-58.5cm) high. The larger kegs will weigh 80-160lbs (36-73kg) when full.

There are various custom sized refrigerators available for this purpose, which can hold one, two or three of the larger kegs, and often include the faucets pre-mounted. Unfortunately, these units are extremely expensive, and seem unreasonably so based on the low volume.

It seems to me that I should be able to build an insulated compartment in which to store one or more kegs, and install a heat pump exchanger, either specially purchased or salvaged from an existing consumer model.

My questions are:

1) Is it practical to build such a unit, assuming a moderate knowledge of carpentry and general know-how?

2) Is it likely to be cost-effective, i.e. significantly less than the $500-1500USD retail consumer units?

3) Is there a particular resource(s) that is likely to be useful as a basic guide to providing the knowledge useful for this?

I would tend to think I simply need the knowledge of what makes for good insulating materials, designing an effective enclosure (accessability), time and effort in building this, and the most critical part being properly mounting and installing heat pump exchanger circuit (and thermostat). It doesn't seem like it should be that complex to cannibalize an existing consumer unit for parts and create something that suits my needs, even if efficiency is less than a consumer model. Then again, it seems build quality is often sacrificed greatly, and I may exceed efficiency I'd get in a retail unit for this application.

Thank you for any opinions, suggestions, comments, etc. that are provided.

09-08-2005, 03:14 PM
The ease depends on the amount of rework you decide you want to do.

If you need to re-plumb the unit, you will have to purchase refrigerant charging and vacuum systems in order to extract the refrigerant charge, vacuum and clean the system after you have changed the tubing, and a good set of refrigerant gauges for determining how much charge to put in your rebuilt system.

OR, with the prospect of beer being part of the picture, you might convince your friendly neighborhood HVAC & refrigeration technician, who has all the tools to do this type of stuff, to help you construct your unit and consume what it stores.

09-08-2005, 07:04 PM
This sounds reasonable... I hadn't really considered replumbing it, as I don't know what's involved, but I can imagine this would open the options quite a bit.

My initial thought was to take the complete circuit, including coils, from an existing fridge and attach it to a new one.. though thinking about that now, I realize that might be difficult, since the tubing would need to be cut at some point (or make a hole and build around it).

My main question is, is this really as "easy" as it seems it should be? E.g. while I need to know RF theory to design a good performing antenna, this is more an issue of make an insulated box, and attach the basic cooling circuit to it?

I was unable to find any references to such home-made units last night, but maybe I was looking the wrong places.

09-08-2005, 08:21 PM
I was unable to find any references to such home-made units last night, but maybe I was looking the wrong places.

Hi Macker

I'm sure that you will not find any "home build" pages for this project, as, like nuclear fission, refrigeration is not a DIY hobby.

Refrigerants work under high pressures and require specialist tools and knowledge. Are you aware of the study of Thermodynamics?

What you want to do is cool kegs of beer. nothing wrong with that, and if you manage it, I'd like to share a beer or two with you.

Your cost ceiling of $1500 or 900(approx) would be reasonable if you already had the necessary tools but as a novice, most of this cost would be spent on tools and not the end result. The suggestion by Glabah to contact a local fridge guy to help out is a good one and should save you cash and time in the long run.

10-08-2005, 02:10 AM
I don't have any desire to spend significant amounts of money on specialized tools; if it's going to require specialized tools or knowledge, then I'm happy to hire someone else. One aspect of this, in considering it, is to apply my knowledge of carpentry/etc. to construct an insulating container, that someone else can equip for refrigeration. Since there's readily available consumer units that fit the requirements (but are not in the desired configuration), I'm looking at this as probably not requiring an extremely sophisticated design. I'm sure a unit designed professionally would yield better efficiency, etc. but that would exceed my budget and needs.

I do not have a knowledge of the study of thermodynamics, and I am not looking to design a high-end or large-scale unit for commercial use. I am aware of the pressures that can be involved (compressor), risks of refrigerants (be it CFC, ammonia, propane or even *****), etc. That said, I think it's fair to say that it's relatively straight-forward to design and build an "icy ball" (anhydrous ammonia heat exchanger) using common parts (propane tank, co2 tank), and in the same manner it should be reasonable to make _basic_ modifications to small-scale refreigeration units, in the same way that someone might add an external faucet for a "kegerator conversion" to an existing fridge, or to construct a peltier-based cooler (e.g. lunch-sized coleman).

I have encountered brief mentions of people doing things, e.g. extending a fridge with additional insulated area. I am not under the misconception that this can be done for all purposes, as it would be easy to exceed the capacity of a compressor and burn it out due to excessive runtime, etc. I do not pretend to understand how to determine these amounts. Nor do I have a desire to take up an extensive study in the field of refrigeration or hvac sufficient to do this on a professional basis.

That said, I have to think there is basic books or resources, an "introduction to refrigeration" that will not only provide me with a "here's how to make cold air", but also "here's things you should know". Again, what I'm looking to do is work out the concept for what I want (e.g. general design), evaluate the scope and cost of the project, and enlist the help of a skilled professional where appropriate.

If it seems that I'm going counter to the intent of the site or desire of the members, please let me know. The impression I'm getting is "you could hurt yourself, call a professional and pay them"; while I'm happy to do that, I want to be able to say "this is what I have in mind", and not engage in a mutual waste of time because I don't know what is practical, or because it will exceed my budget.

I appreciate the replies received thus far, and will watch for any future replies, and only reply further if to answer a question, etc. I hate to ramble, and feel like I'm doing it now.

EDIT: I guess what I'm trying to say is, I'm not pretending to be an engineer on this, and I'm not trying to replace someone with HVAC/refrigeration knowledge. My goal isn't to try to do something that I shouldn't be doing, but to know enough to know what I want done, and why I'm paying someone else to do it. My experience of refrigeration is as an end-user, and small-scale water cooling / peltier cooling applications for electronics.

10-08-2005, 08:30 AM
Hi Macker, and welcome. This sounds like a project close to many frigie's hearts! :D
I think the main thing to remember is that refrigerant is dangerous if you don't know what you're doing. With that in mind, you have 3 options:
1. Buy a commercially avaialble beer chiller.
2. Recruit a local frigie to help you out - they'll have all the gear & hopefully also the knowlege to help design the system.
3. Get some help from us to design & build it yourself - as long as you can source a complete fridge system that will closely match your heat load (maybe a small 'window rattler' a/c unit for e.g.) that you will not have to mess with other than plugging it in, (and maybe getting 2. above to check it over) then you'll probably be okay.
Frank is right to say that refrigeration is not a DIY hobby, but if you're not needing to build a system or alter an existing one (Like ripping one out of an old domestic fridge for e.g.) then I can't see a problem.
On the other hand, have you considered buying a large enough second hand domestic fridge? Assuming that the side walls do not have refrigerant pipe work in them (perhaps one of the domestic spoecialists can tell us?) you could drill through to fit your taps, and use hypafoam to provide a seal around the beer pipe. This is important as otherwise you'll get moisture in the insulation, thus damaging it, especially if it freezes.

10-08-2005, 01:02 PM
Hi Macker, you reminded me by myself in the past. I used to build electronic cuircits as a hoppy using some books for begginers. In fact, refrigeration is not the same! to build a refrigeration system you should have a ropust refrigeration background and you will not find books for biggners. Besides, as the other guys said, refrigeration field is a little bit hazardious: high ***** pressure, high electric current draws by the compressor...etc.

I suggest you to buy new refrigerator and then enjoy your beer!.



10-08-2005, 08:34 PM
Hi Macker

I've had an idea.

To do what you want is really quite simple. Get hold of an old or second hand chest freezer, one big enough to hold the beer kegs. Replace the thermostat control to allow the system to shut off at 12C. Feed your beer pipes out of the chest freezer to your beer taps and hey presto, a cheap and simple solution ready made with a small modification. :)

make sure you plug the pipe hole with putty to stop condensation and make sure you don't put the hole through the evaporator section

10-08-2005, 09:10 PM
Hey Frank, I think I already suggested that one! :D :D :p

10-08-2005, 10:20 PM
Hi Macker

I've had an idea.

To do what you want is really quite simple. Get hold of an old or second hand chest freezer, one big enough to hold the beer kegs. Replace the thermostat control to allow the system to shut off at 12C. Feed your beer pipes out of the chest freezer to your beer taps and hey presto, a cheap and simple solution ready made with a small modification. :)

make sure you plug the pipe hole with putty to stop condensation and make sure you don't put the hole through the evaporator section

Good idea.
A VC1 works for this. I did the same mod for a chef who wanted to keep home made sorbet in the freezer but the current stat was to cold.

10-08-2005, 10:39 PM
macker although i agree with what everyone has said i think there is a site that might be of use to u i found it by entering marine refrigeration on google i dont have the web address at the minute but it is at work try entering it on a server over there as it is a american site it tells you all about what you need to do and calculations it is based on a cold box for a boat but i am sure you could use it 4 beer if you cant find it post back and i will post the full address

11-08-2005, 10:18 AM
The chest Freezer conversion works a treat Ive done a few as it seems the people around here dont mind a drink on a hot day or any day with a y in it.
The go is to locate both the evaporator (cold ) and condensing (hot ) piping circuts as they are both hidden inside the insulated cabinet .The easist way is to run the freezer for about 1/2 hour with the lid open shut the lid run for another 1/2 hour, the cold pipes should be evident by frost or sweat mark and the condensing pipes will show up with a non contact thermother or if you have good fingers and a bit of patience by feel
Jaycar electronics offer a Coolmaster in line temperature controller which is a in line interupt thermostat


sorry I dont know how to do hyperlink The kit number is KC -5413

This unit will only go down to 2.5 degree so some modification may be necessary for a beer chiller I normally use a carel ir33 digital controller but this may add to much to your cost
Just one thing Frank was that 12c you meant or -1.2c this is beer we're talking about not tea

11-08-2005, 10:21 AM
Well I'll be a Dingo's Donger I do know how to hypertext

Andy W
11-08-2005, 12:54 PM
Good idea.
A VC1 works for this. I did the same mod for a chef who wanted to keep home made sorbet in the freezer but the current stat was to cold.Fit a cheap elliwell stat or similar and you have full control of temperature, differental and even defrosting. I like the chest freezer idea but I would personally design it so the kegs are raised from the base of the freezer and a circulating fan is installed to give air movement. Another alternative but would incurr some costs would to go to the local council waste tip, look for two refrigerators with plate evaporators and install the evaps inside of a custom built insulated box and then size up a single compressor to run both circuits. A further way would be to make a water chiller and sit the kegs in water, easy enough to do if the kegs are not too heavy to lift.

11-08-2005, 09:47 PM
I like the beer thing more than refrigeration . . . . if you do it , when you finish it post us photo of the new fridge full of beer

12-08-2005, 09:44 AM
Hi Macker

Replace the thermostat control to allow the system to shut off at 12C.

12C for beer temperature...must taste terrible. here in Aussie we like our beer cold..around 3-4C but it depends which state your from

12-08-2005, 09:49 AM
I did this same sort of thing for a friend once. Got an old temprite filled it with a brine solution. Put it in an old chest freezer that was maintained at 1C. beer pipes went in thru the side of the freezer. Had keg hooked up under the house and beer gun of the temprite.
He had the freezer in the lounge and just used to fill his galss while sitting in the lounge chair

13-09-2006, 02:05 PM
Im in a similar situation to Macker but Im just looking into setting up a keg homebrew after gving up on bottle washing. I have limited space indoors and no garage attached to the house where a fridge could go and there's no way Im running to the shed to get a beer(my wife thinks itd be ok) which is my reason for wanting a more custom made cooling system than others. plus if you use a fridge you need to fit two in it, whether you are using 50 0r 20 L kegs so when one runs out, the others cold,. 2 50s would probably fit allright in a normal full length fridge but to find a fridge to economically fit two 20s or 18s or whatever they are, would be tricky(without going retail). So Im quite in love with Deejays last post. I am definitely into putting the beer under the house and just sacrificing a little of my existing fridge space. Why not just go into the fridge with your beer line (anyone know if you can use copper or has it gotta be stainless)wind it round flat under a shelf or against a wall( back be coldest?) and out. If you can use copper, could you use a small car radiator? Easier still, have your tap inside the fridge, no hole. So, I know its gonna depend on the outside temp of the beer but Im trying to figure out how much line needs to be in the fridge. If you had just a few mates over you might be looking at a litre each an hour. Deejay, did you use brine to stop the beer freezing or could you use anti freeze or something. If you ran through the freezer you probably wouldn't need as many coils and would have a quicker cool down time. I dont know what temperature my freezer is but I would still want to be able to keep other stuff in it. Finaly, and this may not work the way I imagine it, but pubs apparently have electric temprites which cool the beer in line. These I har are insnely expensive and can run up to five different beers. The post mix works similar too dont they? Could you buy a home version of these and could they instantly cool beer in a line. Better still could you make one.Did you get all that. Im not proof reading it so good luck. Macker if Im hyjacking please let me know and Ill toddle along. Thanks New guy

Andy T
13-09-2006, 09:01 PM
The brine(It could be just water in a normal fridge,as it will not freeze) is in a tank in your fridge.This is chilled as normal like anything else in your fridge.The beer pipe runs into the tank and around in loops in the brine,leaving to your beer tap still located in the fridge.The brine acts as a thermal mass colder then the beer.As you draw the beer the beer will transfer it's heat to the thermal mass cooling the beer.The hardest part is calculating the volume of brine required for a constant beer temp during maximum demand.

14-09-2006, 08:33 AM
So, whether I go into the fridge or the freezer, I really need to have it in some kind of fluid to get the heat exchanging efficiently. I like the idea of using the freezer more and more but is it possible to prevent the beer from freezing while maintaining freezing temperature for the icecream and stuff. Would anti freeze do this? Does the solution need to be enclosed to stop evaporation and if I do enclose it wont water sort of rot. Not in the freezer I suppose. As far as volume goes, I guess I need between a six pack and a half cartons worth in there at any given time cause it takes say an hour to cool a beer down and that could easily be drunk in that time. But if its in the freezer, hell maybe it could be just about straight through. With plenty of solution itd be like an instant cooling setup. Would the solution have to be circulated at all to deal with high volumes?If Im shooting off in the wrong direction please say.