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. 

"Dear Veco,

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. 

Best regards,

Craig Briggs

s/v Sangaris

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.

Craig

---In amelyachtowners@..., <uster@...> wrote :

Good morning Paul,

If I may point out regarding the “water cooled” units.
“Chapter 3” of the Installation and Instruction Manual
http://www.coastalclimatecontrol.com/images/PDF/Refer/Frigoboat_Manual_Rev_37.pdf
it says:
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.

Sincerely, Alexandre.



--------------------------------------------

On Mon, 8/6/18, osterberg.paul.l@... [amelyachtowners] <amelyachtowners@...> wrote:

Subject: RE: [Amel Yacht Owners] Looking for suggestions on galley refrigerator
To: amelyachtowners@...
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
the compressors.

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

 

On Aug 7, 2018, at 2:58 PM, James Alton <Lokiyawl2@...> wrote:

Bill Kinney,

   Actually you may have done yourself a favour by using the slotted head style.  While the hex and square drive heads are really convenient since slippage of the tool is reduced, in my experience the maximum torque that you can apply to the head is not nearly as great as with the slotted head in a screw material that is not hardened.  I have driven probably upwards of 30,000 slotted bronze and stainless screws slotted screws and if the tool fits the head really well and the the screws are driven true, it is quite possible to twist the head right off of the screw if too much torque is applied, often without any damage to the slot in the head.  2 years ago, I drove 6000 square drive screws and I had to be quite careful to keep the torque down to prevent the square in the screw from beginning to yield.  I never broke off a single head due to the torque limitation and had to throw out several hundred screws that were damaged.  Future removal of those screws is very iffy IMO.  I think that the square and perhaps the hex drives are more suitable in a material where the head can be hardened such as a deck screw made of carbon steel.  I am not a fastener expert so just sharing my experiences but unless I can find a good reason to switch from the original slotted, I am going back with the original head installed by Amel.   If anyone has any information showing that a head other than hex beats the maximum torque of a slotted head, please enlighten me.

Best,

James Alton

SV Sueño

Maramu #220

On Aug 7, 2018, at 12:10 PM, mfmcgovern@... [amelyachtowners] <amelyachtowners@...> wrote:

Davi,

That screw is black oxide coated mild steel.  It will rust in no time.  You want to use 316 Stainless Steel screws whenever you can on the boat.  Certainly for anything that is exposed to salt water.  Here is a link to a 316 Stainless Steel Hex Drive Flat Head screw should work for this application:  https://www.mcmaster.com/#93395a410/=1e1x4s3

Mark McGovern

SM 440 Cara

Deale, MD USA

 

---In amelyachtowners@..., wrote :

Davi,

That doesn't look like the right screw...  I do not think it is stainless...

The best choice would be part number Grainger Item# 26LG09  But before you order them, pull out one of t he existing screws to be sure the size and length is right!  All I know is what screws were used on my boat...

I used Grainger part number 31JR46.  It has a slotted head. I ordered them before I saw Joel's excellent suggestion to use the socket head screws. Next time!

 

Compass Marine has an excellent "how-to" page on the how's and why's of using butyl tape for sealing deck hardware.  https://marinehowto.com/bed-it-tape/

Bill Kinney

SM160, Harmonie

Annapolis, MD, USA

---In amelyachtowners@..., wrote :

Bill, Hi there.... is this the screw for the job, from grainger? I think I might be needing this soon on my SM #56... Got some butyl tape ordered too...so would I unseat the stanchion, clean the rust from everything, tef gel the screws as per your instructions in this thread, then only use butyl tape to cover the whole stanchion base and rescrew everything down? 

Many thanks... 
Davi

 

 

On Aug 7, 2018, at 12:10 PM, mfmcgovern@... [amelyachtowners] <amelyachtowners@...> wrote:

Davi,

That screw is black oxide coated mild steel.  It will rust in no time.  You want to use 316 Stainless Steel screws whenever you can on the boat.  Certainly for anything that is exposed to salt water.  Here is a link to a 316 Stainless Steel Hex Drive Flat Head screw should work for this application:  https://www.mcmaster.com/#93395a410/=1e1x4s3

Mark McGovern

SM 440 Cara

Deale, MD USA

 

---In amelyachtowners@...,

Davi,

That doesn't look like the right screw...  I do not think it is stainless...

The best choice would be part number Grainger Item# 26LG09  But before you order them, pull out one of t he existing screws to be sure the size and length is right!  All I know is what screws were used on my boat...

I used Grainger part number 31JR46.  It has a slotted head. I ordered them before I saw Joel's excellent suggestion to use the socket head screws. Next time!

 

Compass Marine has an excellent "how-to" page on the how's and why's of using butyl tape for sealing deck hardware.  https://marinehowto.com/bed-it-tape/

Bill Kinney

SM160, Harmonie

Annapolis, MD, USA

---In amelyachtowners@...,

Bill, Hi there.... is this the screw for the job, from grainger? I think I might be needing this soon on my SM #56... Got some butyl tape ordered too...so would I unseat the stanchion, clean the rust from everything, tef gel the screws as per your instructions in this thread, then only use butyl tape to cover the whole stanchion base and rescrew everything down? 

Many thanks... 
Davi