Refrigeration on a budget

[RaymondR]

You can get by pretty cheaply.

My first marine fridge was made from a 12V BD35 compressor I picked up somewhere fairly cheaply, a $60 capillary tube, and about another $60 of copper tube.

We made the condenser by wrapping 1.4" copper around a piece of pipe then putting it into a piece of poly down pipe with a computer fan on the bottom and the evaporator was just 5/16" copper tube bent to fit inside the box with a tube bender. Silver soldered the connections. We scavenged a thermostat from somewhere.

It worked well for about ten years then the compressor seized up, probably due to it having insufficient oil when we installed it.

[Rotan]

Originally Posted by RaymondR

You can get by pretty cheaply.

My first marine fridge was made from a 12V BD35 compressor I picked up somewhere fairly cheaply, a $60 capillary tube, and about another $60 of copper tube.

We made the condenser by wrapping 1.4" copper around a piece of pipe then putting it into a piece of poly down pipe with a computer fan on the bottom and the evaporator was just 5/16" copper tube bent to fit inside the box with a tube bender. Silver soldered the connections. We scavenged a thermostat from somewhere.

It worked well for about ten years then the compressor seized up, probably due to it having insufficient oil when we installed it.

Great account. Thank you.

Originally Posted by Generic Armchair pot stirrer

What an interesting post. Entertaining sometimes, and it shows that some of us have a lot of patience...
But I was trying to figure out why go to so much trouble trying to beat the current with only one paddle, now I have the answer

Its threads like this that remind me why the prices in every port I visit are 5x the home/auto market. Those that have more money than sense cant comprehend any other answer than "oh! ok" when the vendor/mechanic pulls some number out of his $$$, doubles it, and tells you the price.

Its you clowns that pay $1000 for a starter motor worth $125 from any parts store in the world. Its you that sit quietly by while "laws" are passed prohibiting skippers working on their own boat.

Then, comfortable in your smug complacency, you deride from the peatnut gallery, any suggestion that putting the word "marine" in front of any parts listing justifies multiplying its price by 5.

You dont get scrapes, burns, cuts and occasionally electric shocks, cos you dont *DO* ANYTHING!!

Menawhile, I have to wade through your innane comments to get to the juice in a few responses from people that seem to be mostly intimidated by you clowns.

ITS OK TO TRY TO BUILD YOUR OWN SYSTEM ON A BUDGET... no really, it is!

[goboatingnow]

Refrigeration is different then say plumbing , electrics, etc. It needs some specialised equipment and is normally very reliable , especially modern sealed units. Hence few people build up DIY experience. Understandable really.

[RaymondR]

Originally Posted by goboatingnow

Refrigeration is different then say plumbing , electrics, etc. It needs some specialised equipment and is normally very reliable , especially modern sealed units. Hence few people build up DIY experience. Understandable really.

True, but the only extra equipment required is a heat source for soldering, I use a Mapgas torch, and tubing cutters. You can get by without a vacuum pump but one of these will cost about what you'll pay for a fridge tech visit.

If you like a little intellectual activity refrigeration can be a fascinating subject and fixing another yachties fridge when they're in the middle of nowhere with all their perishables about to go bad can make you friends for life.

All in all I'm really glad I chose to become my own fridge tech.

[JimsCAL]

Yes, refrigeration is a bit more complicated than simple plumbing and does require some specialized equipment and knowledge to do things correctly. Also recognize that R-134a is over 1000 times more potent as a greenhouse gas than carbon dioxide. There are EPA rules about the recovery and recycling of refrigerants during repairs that most amateurs flaunt.

[Bowdrie]

Originally Posted by RaymondR

If you like a little intellectual activity refrigeration can be a fascinating subject

Yes, it might have a loose connection to music, enough theory/math to satisfy the "technical", while still requiring a dose of "technique" to satisfy the "art".
Once you wrap your mind around the idea of "boiling" at temps below freezing it's not all that different from the inverse of the Carnot Cycle in a closed system steam engine, which uses compression/expansion/condensing/outside heat source.
The "pre packaged" 12V units are easily installed, widely available, they work rather well, and require little knowledge, (technical,) or "art", (technique).

[Richard Kollmann]

Originally Posted by JimsCAL

Yes, refrigeration is a bit more complicated than simple plumbing and does require some specialized equipment and knowledge to do things correctly. Also recognize that R-134a is over 1000 times more potent as a greenhouse gas than carbon dioxide. There are EPA rules about the recovery and recycling of refrigerants during repairs that most amateurs flaunt.

As a technical situation Do It Yourself adviser most of my life and one that read the Federal requestor weekly during their development and approval of
Clean air act/EPA regulations. I would help an amateur struggling with boat refrigeration and ways to find regulatory meaning. Many times regulations written are influenced by special interest groups and over time are Abated officially or quietly. In many areas of the US and the world R134a refrigerant handling and servicing is legal by any one unofficially Abated. It is of course against regulations to vent any refrigerant to the air. Building and repairing refrigeration if refrigerant is involved you should not need a certificate.

[RaymondR]

I switched to hydrocarbon based refrigerants years ago because of the R134 restrictions. This statement will probably invite a storm of comment along the lines of "You'll blow yourself up.

For my part my analysis is that I am far more likely to blow myself up with the gas stove which is an open ended system connected to a 9 kg gas bottle whereas the fridge has about 100 grams of gas in a high pressure closed system.

[Russian007]

Originally Posted by Rotan

Yes I agree. I dont see the need for 12v compressor with modern inverters running at 98% efficiency and useful for many other appliances.

Is this true? I had thought the loss in efficiency was more dramatic. Only 2%?

[Russian007]

Emily and Clark's Youtube channel has some innovative concepts and may roll out a 12v battery/solar run a/c for small cabins. Might see if they have something to help. Clark has a legit tech background and is an excellent teacher. Their Youtube videos are also unique in that they don't feature gratuitous butt shots of the nice lady of the boat.

[Rotan]

Originally Posted by Russian007

Is this true? I had thought the loss in efficiency was more dramatic. Only 2%?

90-95% depending on temp and input voltage. 98% is probably optimistic.
The point is, if the fridge uses 4A @12v, even a 10% efficienct loss only adds up to .4a. During the day when solar is supplying power its irrelevant, so the total "cost" of the inverter is .4A x 10hrs , which is a total of 4amp hours or 48Watts total energy cost per day. Trivial

[Rotan]

Originally Posted by JimsCAL

Yes, refrigeration is a bit more complicated than simple plumbing and does require some specialized equipment and knowledge to do things correctly. Also recognize that R-134a is over 1000 times more potent as a greenhouse gas than carbon dioxide. There are EPA rules about the recovery and recycling of refrigerants during repairs that most amateurs flaunt.

A DIY will release refrigerant once every 3yrs, 5yrs?
A repair shop 20x per day?
A service technician 5x per week?

I support responsible environmental laws, but this argument is invalid in the context of this thread.

[Richard Kollmann]

Originally Posted by RaymondR

I switched to hydrocarbon based refrigerants years ago because of the R134 restrictions. This statement will probably invite a storm of comment along the lines of "You'll blow yourself up.

For my part my analysis is that I am far more likely to blow myself up with the gas stove which is an open ended system connected to a 9 kg gas bottle whereas the fridge has about 100 grams of gas in a high pressure closed system.

The use of HC's as a replacement to environmentally damaging refrigerants is a positive direction for both consumers and the environment. HC's cost less, are less toxic to both humans and the environment, and operate more efficiently than other systems. The big problem with HC Refrigerants in boats are the explosive flammability as a many Bick cigarette Lighters releasing the same HCgas. The problem on carbon based refrigerants in boats is much the same as gasoline in boats as they are both heavier staying low in the boat hull as they both are heavier than air.

Because of the lack of the marine industry response during the years these regulation were developed and now plans to phase out 134a we are forced to take risks like using flammable HC refrigerants. I had my own gasoline powered boat blow up while cruising. With extraordinary detection or continuous bilge fan running the fire risks of using HC refrigerant can be managed.

Because of the small 12volt refrigerant units containing less than 200 grams of HC can safely be managed with a small leak.

[OzeLouie]

Originally Posted by RaymondR

I switched to hydrocarbon based refrigerants years ago because of the R134 restrictions. This statement will probably invite a storm of comment along the lines of "You'll blow yourself up.

For my part my analysis is that I am far more likely to blow myself up with the gas stove which is an open ended system connected to a 9 kg gas bottle whereas the fridge has about 100 grams of gas in a high pressure closed system.

Interesting Raymond. Can you report a bit about your hydro system?
Back when R12 was getting the flick (sadly) my mentor did a lot of trials with the propane / butane blends and got good results at higher back pressures but found it tricky when lower (freezers etc) The problem was 'gliding or separation. He did nothing with it since. I can see it is good for air-cons and medium temp fridge work and notice how well R600 performs in some of those imported fridge / freezers so keen to get any news updates you may wish to share.

Cheers Louie

[RaymondR]

Hi Louie,

The one I use is Hychill Minus 30 and the full specs can be downloaded from the Hychill site in Melbourne.

This is the second of their Hydrocarbon refrigerants I have used the previous being not so low temperature.

I started using their products after a bad experience with a warranty job wherein the fridgy had forgotten to bring his vacuum pump and compressor power draw was excessive because of air in the system. Not being able to access R134 and reluctant to risk a second bad experience I decided to try the Hychill product which is readily available from auto parts stores.

I have run the refrigerant in three different systems so far which constitutes about ten years overall of experience with it. From a performance viewpoint I have noticed little difference between the R134 and Hychill's hydrocarbon based products.

Hydrocarbon based refrigerants are very common in European domestic refrigeration and when I spoke with the Hychill techs I was informed that it was their major market.

Danfoss manufactures a hydrocarbon compressor although I suspect the only difference is in the external wiring and electronics enclosures.

Hychill's products are claimed to be compatible with both hydrocarbon and ester based refrigerant oils.