Want To Buy: Frigoboat / Waeco Keel Cooler Condenser

[pparra]

Hi,I'm looking for a new or used Keel Cooler condenser for my sailboat fridge but having some difficulties in finding one thru internet. The other problem is that I live in Brazil, which might make some sellers afraid of payment and shipping issues.
Any help is welcomed!

Tks and rgds, Paulo

[senormechanico]

Try suremarine.com

I don't know if they'll ship to you or not, but they're good people to deal with and they know their stuff.

We got 30% off the listed prices.

http://www.suremarineservice.com/CFS50.aspx

[CarinaPDX]

It might be easier, and higher quality, to make one yourself or have it made for you locally. A bronze thru-hull, a small bit of bronze plate to close the hole (with two holes in it) and a meter or so of 8mm (probably) bronze or cupro-nickel or Monel tubing. Shape then braze it together, and fill the thru-hull with something like an epoxy filler. Sorry I can't seem to find a photo of mine.

Greg

[pparra]

Dear Greg,

Your suggestion seems to be similar to the Isotherm thru hull solution, isn't it?

Did you fabricate yours? Did you use the tubing for water or gas cooling?

My idea is to replace the condenser.

In the Waeco/Vitrifrigo Keel Cooler, the refrigeration gas tubing is encapsulated in the bronze sinterized body which remains in constant contact with water in the hull outer surface.

I modified my air-cooled fridge system, inserting the condenser/cooler in a box filled with fresh water, which comes from my water tanks. It works good but it is dependent on having water inside the tanks, and I believe that the temperature outside is lower than inside the tanks.

Thanks for your help.

Rgds, Paulo

[CarinaPDX]

No, not really similar. The Isotherm solution is to hide the coil of bronze tubing inside the body of the oversize thru-hull, and still use the thru-hull as normal (typically for galley waste, with its food particles and fat). Even without the diet from the galley things are going to grow inside around the coil - I can't imagine trying to clean it out. And the coils are out of the flow of water along the hull so it will not be as effective for heat transfer. As with other Isotherm designs it is different from the norm but ultimately flawed (that is a thread of its own).

The Frigoboat design uses a relatively small amount of tubing surrounded by sintered bronze to increase surface area. Like the Dynaplates for electrical ground this area becomes effectively reduced as the spaces fill up with growth and debris and corrosion. And sometimes the sintered bronze can start to crumble off. (One of my 20 year old Dynaplates is in great shape, the other is crumbling.) My friend in Turkey that assembled my current fridge said he had to replace several Frigoboat heat exchangers, so beware.

AFAIK all of the "keel cooler" solutions run the refrigerant (r134a) through the keel cooler; the whole point is to get away from pumping water. For most systems this is the only condenser. Of course I had to get a little too clever and put both a keel cooler (first) and a fan-circulated air-cooled condenser in the system. It has been useful during long haulouts but is a little more critical to the amount of refrigerant (or at least that was what I was told).

I will keep looking for the photo but for now imagine bending 1.5m of 8mm tubing in the middle, back on itself (180 deg) so the sides are 4 or 5 cm apart. At about 0.5m from the bend put a slight "S" bend in both sides so that they continue parallel and close enough to fit through the two holes in the plate that you have fit across the mouth of the thru-hull. Then bend both of these ends just after the S bends 90 degrees, so that the loop will lie flat along the side of the hull while the tube ends extend into the boat. Braze it together, fill the interior of the thru-hull with something to seal it (in case of a leak in the brazing). Then solder it into the system after the compressor.

Good Luck,

Greg

[CarinaPDX]

Addendum: while constructing the keel cooler braze standoffs to the tubing to hold it in place maybe 5mm off the hull.

[pparra]

Greg,

I think some fishing boats have this kind of solution for cooling engine, but with more loops, using steel piping (cheaper to replace).

How do you avoid it to be damaged during hull cleanings/scrapings? It seems so exposed to me...

Paulo

[CarinaPDX]

I have never had a problem with damage - even cosmetically. It is painted with bottom paint and I have never seen any damage to the paint either.

I mounted the compressor far back in the boat (behind the engine) so that I wouldn't have to listen to it while trying to sleep, and using less valuable storage space than in the galley (and not putting more heat into the galley). The small 12VDC compressors need a long length of capillary tubing on the compressor side anyway, so that worked out well. When I replaced the (non-functioning Isotherm) system I installed the new compressor there as well, and put the thru-hull for the keel cooler right beside the compressor. The loop trails aft and up a bit to approx. matching the water flow. This loop is in the (concave) hollow of the port quarter, about 0.5m ahead of the end of the keel. Dangerous flotsam is not likely to flow that close to the hull that far aft, and lifting straps or dock pilings can't get in to it either. The bronze tubing is pretty strong - it is a thick wall and requires heating in order to bend. The only tricky part of this project is to find the right tubing: it needs to be strong, corrosion-resistant, and close in galvanic potential to the bronze used for the rest of the fixture. And be certain before connecting it to de-burr the ends and clean/flush the interior well so that there is nothing that will plug the capillary.

Greg