Plumb freshwater line through fridge for cold tap water

[andrewvik]

Hi, I sail mostly in the Med during high season, and a glass of cold water is always in demand. I thought that instead of opening the fridge and reaching for the water jug each time, I could plumb a pressurized freshwater line through the fridge ending up at a dedicated faucet at the sink. On-demand cold water!

First I started looking at cool-exchangers, such as these wort chiller used in home beer brewing... https://hardwarefactorystore.com/col...25598239146084

Then I began thinking that some kind of reservoir used in home refrigerators would be better... https://www.repairclinic.com/PartDet...911502/2659565

Has anyone done something similar? I figure that I'd only get a few glasses of cold water at a time, depending on the size of the reservoir. Any armchair engineers out there care to brainstorm this one for a bit?

My fridge is a simple 3.5cuft box with a rectangular O-shaped condenser. Only things placed within the condenser freeze.

Of course, I could just fill my insulated 0.75-liter water canteen each morning, but that's a far less sexy solution.

Andrew
s/v Geja
www.SailGeja.com

[atoll]

we just have a 10 liter container with a whale hand pump above the fridge worktop.
works great,
you need to insulate the hand pump as it gets condensation on it and rots the work top
.
to add a pressurised system a stainless tank with an inlet and an outlet to a small spigot type tap would probably work.

the only problem was the crew would fill their water bottles with it so 10 liters was used up fairly quickly

[CaptTom]

You asked for armchair engineering...

My first thought was a coil of copper tubing. You could also run it flat, back and forth against the back wall of the fridge interior. For even more volume, you could run a large coil around all the inside walls. Obviously the wider and longer the tubing, the more cool water you'd be able to get before it started coming out warm.

Next, get a drinking water faucet at the sink. Connect it via one of those under-sink filters using plastic tubing. Run the plastic right up to and maybe into the fridge, since copper would absorb the heat faster.

[Mirage35]

Our home refrigerator does this - its mechanism is nothing more than a coil of plastic tubing inside the fridge. It provides about two glasses of cold water before it has to sit and cool off some more.

[Woodland Hills]

How much room temperature water will be in the line between the fridge and the tap? How much freshwater will you waste running the tap until it gets cold? If it’s one glass full then you just doubled your water consumption for cold drinks.

[andrewvik]

Originally Posted by CaptTom

You asked for armchair engineering...

My first thought was a coil of copper tubing. You could also run it flat, back and forth against the back wall of the fridge interior. For even more volume, you could run a large coil around all the inside walls. Obviously the wider and longer the tubing, the more cool water you'd be able to get before it started coming out warm.

Thanks CaptTom. This coil of copper tubing, is this available off the shelf? Or something a plumber would build?

Cheers,
Andrew

[andrewvik]

Originally Posted by Woodland Hills

How much room temperature water will be in the line between the fridge and the tap? How much freshwater will you waste running the tap until it gets cold? If it’s one glass full then you just doubled your water consumption for cold drinks.

Woodland Hills, I included the photos above to show how close the fridge is to the sink. I guess there would be up to 8"/20cm of potentially warm hose. Might not be much liquid if, say, 1/4" hose were used, which I'd wrap in insulation anyway.

- Andrew

[CaptTom]

Originally Posted by andrewvik

Thanks CaptTom. This coil of copper tubing, is this available off the shelf? Or something a plumber would build?

Yes, off the shelf. Any Home Depot or Lowe's will carry it.

They also carry plastic tubing. It's used for refrigerator water/ice maker systems and under-sink drinking water filters and dispensers.

Look around in those sections for connectors, fittings and (important!) shut-off valves. Sometimes you can even find a knowledgeable sales person to help piece together the system.

Using plastic tubing may be the better option for ease of installation. Bending copper tubing is easy, but it's also easy to collapse the inside of the bend if you try to make it too tight. I'd personally go with copper because it's much, much better at heat transfer, which is sort of the whole point here. Plastic is an insulator. It'll take a lot longer to cool down the water inside, so you'll get fewer cool cups per hour (if I may invent a new unit of measurement.)

[OldGreyB]

So some further arm chair engineering. I took your fridge cubic capacity and generated an estimate of the dimensions from the photos. I have used 14" wide, 22" long and 19" deep.

Soft water quality 3/8 copper tube is available in coils from your standard big box hardware stores. Link from Lowes below as an example. Recommended manufacturers bend radius is 11/2 " , link to tube bender example below. Use one to ensure you do not crimp the tube when bending. Making vertical S style coils on the sides does not give sufficient tube volume capacity of chilled water.

However CaptTom's suggestion of running coils around the inner wall surface the same as a beer chiller wort is the way forward. With the above estimated internal wall size, and with the 11/2 " radius bends at each corner, one complete 3/8" tube circuit would yield 7.5 fluid oz (222ml), less than an "standard" 8 fluid oz (250ml) glass of water.

You would need to stay away from between the wall and mounted condenser, as that could freeze the water, but if you ran 6 coils below the condenser and then out to your faucet, you would obtain up to approximately 5 glasses of cold water in one pour.

With the dimensions I have used, you would need around 40' of tube, including the external connections. Insulate the copper or plastic on the way to the faucet. Have the water enter at the bottom of the fridge and out on the corner where you are placing your faucet.

Your needed length of copper tube (and hence volume capacity) will depend on your actual fridge dimensions, number of coils you can install, connection point to potable water system and faucet.

I would install a water isolator on the copper tube before it enters the fridge, so if you damage the tube in the fridge, it can easily be isolated. You will find compression connectors for the tube at hardware or plumbing suppliers. If you are typical boat maintenance handy, then it's an easy one day project once all the materials and tools are assembled. Links here to examples of tube and bending tool.

https://www.lowes.com/pd/3-8-in-x-20...oil/1000404411

https://www.lowes.com/pd/BrassCraft-...nder/999903819

Happy cool water drinking.

[CaptTom]

Originally Posted by OldGreyB

So some further arm chair engineering. I took your fridge cubic capacity and generated an estimate of the dimensions from the photos.

Wow. That's some serious arm chair engineering. I'm not an engineer. I don't even own a striped hat. But I know a good plan when I see one!

[Red Sky]

2 20oz water bottles. One, uninsulated aluminum or S.S. in the fridge, one insulated for drinking out of. 20oz lasts long enough for the fridge bottle to chill. One set for each crew member. This allows us to use the water filter for our chilled drinking water.