TheRecklessEngineer Posted May 30, 2006 Share Posted May 30, 2006 Now my hybrid is on the road, and its nearly summer, I need something to chill beer ...Im planning on using bits of an air con system from a RR to make a mega fridge, and have a few questions.... Ive have so far acquired an air con compressor, radiator, and filter. As far as I can tell I need an expansion thingy and a condenser (+ some switchy electrics on the clutch for temperature control) to make it chill stuff. Is there anything else I need? What sort of pressures are involved with air con systems? High pressure bit? Low pressure bit? Can I use a series oil cooler as a condenser? What do the wires do coming out of the filter? What happens if I leave the compressor running accidently? Any chance of overpressure? What sort of pressures are involved with domestic fridges? Would it be better to gut a fridge and simply use my air con compressor instead of the original? Anything I havnt thought of? Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted May 31, 2006 Author Share Posted May 31, 2006 Ive been doing some hunting on the net. Seems I can just attach an expansion valve and evaporator. So...anyone around Soton got either hanging around? Folding beer tokens on standby. Quote Link to comment Share on other sites More sharing options...
simonr Posted May 31, 2006 Share Posted May 31, 2006 Have a look at: My DIY Air-con Which explains most of the components you need to find. Go and chat to your local Climate Centre - they are mostly very helpful and interested in people doing it themselves! The peak pressure in the system is unlikely to be more than about 200psi. Most oil coolers seem to be able to survive this, however, I suspect that if you are after a mega-fridge, you would be better just wrapping copper tube around the inside of the box you are going to use. The system can go over-pressure if there is insufficient cooling. You would put a pressure switch in the high pressure line which switches the condensor cooling fans on, and perhaps another at a higher pressure to shut the whole thing down. You need a dryer/reservoir in the high pressure line. You might not think you need this - but trust me, you do. I would buy a new dryer - they are only £15 or so. If your pump does not have ports on the back for filling the system, you will need to add these. I'd use the older screw on type rather than the more modern bayonet fill hose adaptors. You really ought to get a grown-up to pressure test it, evacuate the system (to remove all the air & water) and to fill it with gas, but that shouldn't cost you more than £50 unless you know someone! Si Quote Link to comment Share on other sites More sharing options...
Mark90 Posted May 31, 2006 Share Posted May 31, 2006 I have some bits in the shed from a RRC air-con system, I only wanted the compressor. Dunno what they are but I can take pics if they might be any use to you. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted May 31, 2006 Share Posted May 31, 2006 James - got your text, don't know if I have any bits, there's the remains of the RR Dan broke in my field so I've no idea if that had a/c? Quote Link to comment Share on other sites More sharing options...
rick Posted May 31, 2006 Share Posted May 31, 2006 Yes, an air con compressor is fine to use. ThermoKing use virtually off the shelf Sanden compressoors in their smaller systems (eg small milk trucks and delivery vans) Cleanliness is next to Godliness with refrigeration. All fittings, pipes, etc need to be kept capped at all times except when being assembled. Don't open the drier until you are going to use it. Once fitted, purge with dry nitrogen and pressure test, then evacuate. The oil used in the compressor is also hydroscopic (absorbs moisture) so it needs to be kept closed. The TX valve capacity needs to match the system capacity (kw/tonnage) You'll need a thermostat, and need to make the decision will you mount it on the evaporator or air. If using a static evaporator coil, best to mount to the coil. Standard domestic fridges run at around 0 psi in the low side and 120-180 psi in the high side, depending on ambient (static coil). Commercial fridges/coolrooms, depending on conditions wanted (eg. humidity) run from around 15 psi upwards on the suction side and usually range from 100 to 150 psi on the discharge side, generally 125psi @ 25*C (fan cooled) on R134A. Quote Link to comment Share on other sites More sharing options...
Jen Posted May 31, 2006 Share Posted May 31, 2006 James - got your text, don't know if I have any bits, there's the remains of the RR Dan broke in my field so I've no idea if that had a/c? Nope, no air-con on Fluffy... Quote Link to comment Share on other sites More sharing options...
rick Posted May 31, 2006 Share Posted May 31, 2006 you do realise that the average air conditioning compressor is capable of refrigerating something like a 5'-6' square insulated box down to 0* ? Anything smaller and you'll have serious freezer. Might be easier/cheaper just to buy a Waeco or Engel. Quote Link to comment Share on other sites More sharing options...
simonr Posted May 31, 2006 Share Posted May 31, 2006 you do realise that the average air conditioning compressor is capable of refrigerating something like a 5'-6' square insulated box down to 0* ?Anything smaller and you'll have serious freezer. Might be easier/cheaper just to buy a Waeco or Engel. That's what a thermostat's for! Looking at it from another point of view - it will cool a can of coke from 30 degrees to 4 degrees in only a few seconds. How cool is that! Si Quote Link to comment Share on other sites More sharing options...
TheRecklessEngineer Posted May 31, 2006 Author Share Posted May 31, 2006 you do realise that the average air conditioning compressor is capable of refrigerating something like a 5'-6' square insulated box down to 0* ?Anything smaller and you'll have serious freezer. Might be easier/cheaper just to buy a Waeco or Engel. Yup. Thats the idea - ive got the military jerry can holes on each side of the rear tub. One is going to be refrigerated - can just about get a crate of beer in it Shouldnt take long until even the cheap nasty stuff is drinkable Cheers for the help...ill let you know how I get on Quote Link to comment Share on other sites More sharing options...
Gnomeranger Posted June 1, 2006 Share Posted June 1, 2006 I have played with a 7.5ton box boddied truck with only a humble Sanden to cool it. How about a nice sight glass to see when it's full. Quote Link to comment Share on other sites More sharing options...
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