Re: Fridge/freezer cooling

Sv Garulfo

My two cents:

* Risks of freshwater contamination from refrigerant leak:

1. A refrigerant leak will soon be visible by the fridge malfunctioning. It wouldn’t be a case of a silent killer,

2. A leak in the condenser is made less likely by circulating freshwater,

3. If a refrigerant leak happened in the condenser, the r134a refrigerant would bubble up and not dissolve to any significant amount in the water,

4. If a leak happened in the condenser, the oil carried out by the refrigerant (however small amount) would stay at the surface (being less dense and dropped in from the top of the tank). It wouldn’t be sucked in the freshwater circuit. 

* Risk of circulating circuit leak emptying the freshwater tank:

5. It’s low risk but could happen. The symptoms would be the same as with saltwater (in the bilge or in the various compartments in the saloon), but the consequences far less worse (salt vs no salt). At a pump rate of a few litres per min, even a (how likely?) fully breached circuit would take time to empty the tank. 

* Health risk of freshwater contact with condenser:

6. The condenser is most likely made of cupronickel. There is no real study that I could find of the health impact (as per Bill R.’s point regarding liability), probably because it’s an expensive and pointless freshwater carrier, when copper is available and widely used. So unknown, but probably not very relevant, given Nickel is used in some platings of freshwater application. And to be put in balance with the other possibly worrying health hazards (VOCs in varnishes, PVC, anti fouling paints when you swim, clean the hull or make water, UV or antiUV cream, alcohol intake, ...) and benefits (insert you favourite here) of boat life.
As a side note, keelcools are made of cupronickel too, so they don’t help as a replacement of the condenser with circulating freshwater. 

* risk of warming the fresh water to unsafe temperature: 

7. Well, that’s difficult to theorise. Fibreglass conductivity, heat exchange with the surface air, freshwater replacement rate, etc. In practice, I’ve met Amels with full freshwater circulation and none could measure a difference between tank water and surrounding sea water temperature, and I’m not shocked. I would even think the frequent circulation and aeration of the freshwater helps prevent growth in the tank. 
If one worries about the temp of their freshwater tank rising, one should stay in high latitude sailing grounds. Ceramic filtering is a must, if only for taste.

So in conclusion, I think freshwater cooling (copper coil plunging condenser or freshwater water circulation) has more benefits than drawbacks, the main one being the shipyard not having the regulatory means to implement it. 



On 26 Apr 2022, at 10:06, Bill Kinney <cruisingconsulting@...> wrote:

There is NO filter I would ever trust to remove the contaminants from a refrigerant leak into the drinking water without rather sophisticated testing to be sure it actually worked with the actual chemicals at issue.

Propylene glycol is the basis for many of the non-toxic heat transfer solutions used in the food industry. It is usually easy to detect by taste in plain water before most onboard test methods would measure its presence.  You likely consume some every day in your normal food intake.  If you are concerned about it, you COULD just circulate water, but you would have issues with biological growth and corrosion, but still way better than using salt water!

Bill Kinney
SM160, Harmonie
Palmas del Mar, Puerto Rico

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