Out of curiosity I asked Veco (Annapolis Frigoboat/Climma distributor) about their warning to use only sea water for cooling, not tank water. My questions are below with their answers in red.
I see in your Installation and Instruction Manual that you have a warning in Chapter 3 that the W35F and W50F Refrigeration Systems are designed
to operate with sea water cooling only, not water from water tanks, etc. because serious health risks can occur. Frigoboat systems are designed for use with
sea water only. There are no food-grade materials used, and if a condenser rupture were to occur there would be contamination of the drinking water from refrigerant and oil if the system was installed using the boat's water tanks.
I'm guessing the concern with using recirculating cooling water from a fresh water tank would be if the tank water were to heat up a lot or become insufficient, the refrigeration
may not provide adequate cooling and food might spoil causing illness (and possible legal ramifications for your company). Absolutely. Also, we would rather not have the reputation of Frigoboat slighted by operators broadcasting of poor
performance when in fact their systems have been installed and operated in a non-standard way.
Owner error might also allow the tank to become empty, although the system seemingly would respond as it would were a sea water feed to become clogged and no equipment damage would
result. There is a temperature sensor on the condensing coil that will stop the compressor if it is seen that there is an inadequate supply of cooling water.
Can you confirm that the warning is indeed one to prevent owner error or is there actually an engineering issue with using fresh water from a tank? That certainly seems not the
issue as the system, I'm sure, will work fine in fresh water. By using recirculating water in a tank, you are adding several more steps of heat exchange. By using sea water we are always using a fresh source of water at a stable temperature.
Heat travels from a higher temperature object to a lower temperature one, so for heat exchange to take place, there must be a difference in temperature between the two mediums, and the greater the difference, the more the heat exchange. The water recirculated
back to the tank will be at a higher temperature than the water in the tank and so it will heat the water in the tank. The water in the tank has to be considerably warmer than its surroundings before it can dispense some of that heat, so the water in the tank
will be warmer than the surroundings and the sea water. As the water in the tank gets warmer/hotter, there is less heat exchange, less efficiency, and more power is consumed due to elevated head pressures in the compressor. The Frigoboat W35 and W50 systems
are designed to operate efficiently and safely with sea water at the maximum expected temperature.
I didn't word my last point very well - I meant to point out that the system doesn't care if it gets sea water or fresh water from, say, a river or in a lake. It's just a matter
of them not wanting owners using tank water to avoid possible complaints, claims or the remote chance of drinking water contamination.
, <uster@...> wrote :
Good morning Paul,
If I may point out regarding the “water cooled” units.
“Chapter 3” of the Installation and Instruction Manual
NOTE: The W35F and W50F compressors are designed to work with sea water only. They are not designed to use water from other sources, i.e. water tanks, skin tanks, or coolant pumped through secondary heat exchangers. Serious health risks and/or performance issues
can occur if any form of liquid coolant delivery is used other than sea water being pumped directly into the system and then expelled back overboard.
I assume this is some lawyer statement to prevent any type of potential lawsuit should the system leak into the fresh water tank.
Personally, I would not have any issue using the fresh water tank, but wanted to point out the information.
On Mon, 8/6/18,
osterberg.paul.l@... [amelyachtowners] <amelyachtowners@...> wrote:
Subject: RE: [Amel Yacht Owners] Looking for suggestions on galley refrigerator
Date: Monday, August 6, 2018, 8:00 AM
Mark! Did you consider to have a water cooled
compressor? We have changed the cooler and compressor in the
fridge box. To a water cooled, I also build a freezer where
the dishwasher was, also water cooled. Both compressors are
cooled by circulating fresh water from the drinking water
tank. Limited corrosion no growth of barnacles. No problem
to use when on the hard, and very energy efficient. No noice
from any fan. Took the water from the manual pump outlet to
I have thought of doing something about the fridge cabinet
as it get cool, but work most of the time and make noice
even after I changed the fan. One thought was a drawer
fridge, terribly expensive and does not match, or change
compressor and evaporator. I think I know the answer now.
Paul on SY Kerpa SM 259