Is water cooled small refrigerator really a good idea.

[senormechanico]

I'm in the PNW with cool salt water, but in the summer we go to Desolation Sound for a couple of months.
The water temps are in the mid 70's and air can get to 90 f.
All the while, we're carefully adding a can or two of 7up or V8 or similar.
Occasionally, the fridge seems to go into a continuous running and temp goes UP.
I shut it down for an hour and then it goes back to normal.
I have already added a cooling fan with adjustable snap disc thermo switch to the top of the compresser which exhausts the air to the cabin.

Oh, and I almost forgot, we have a separate homemade Aerogel freezer bag which we power with 5 lb Arctic Tundra blocks.
Every morning, we swap them into the refrigerator freezer compartment.
The fridge really gets a workout, but we've got enough solar.

Just to throw another log on the fire, would there be any advantage with a BD35/keel cooler system of ditching the cap tube for a TXV?
Just musing here...

[Typhoon]

Sounds like you have something else going on , maybe moisture in the system .

With a TXV system you don't need a keel cooler or any other type of water cooling . You can't really just add the TXV to cap tube system they are completely different designs. You could use your compressor and controller if they are in good shape and build a system around them .

A condensing unit built around a TXV looks completely different .

Regards John.

[Typhoon]

Also to address the heat put out by an air cooled unit you have to ask yourself, do you feel the temperature rise inside your boat when there is an extra person inside?

A person radiates around the same amount of heat as a Bd35/50 Danfoss compressor , but only when its running.

Regards John.

[JON REISWIG]

Originally Posted by woodenboats

Are you aware of Isotherm's "Self-Pumping" (SP) system? Watercooled, but without a pump, uses the galley sink's through-hull.

The Isotherm SP using my galley sink works well in SE Alaska We have had it for many decades on a FUJI 35 Jon Reiswig

[senormechanico]

Originally Posted by ColdEh Marine

Sounds like you have something else going on , maybe moisture in the system .

With a TXV system you don't need a keel cooler or any other type of water cooling . You can't really just add the TXV to cap tube system they are completely different designs. You could use your compressor and controller if they are in good shape and build a system around them .

A condensing unit built around a TXV looks completely different .

Regards John.

Thanks John,

The system is only 5 years old.
Maybe I'm just pushing it too hard?
I didn't have enough space to install a BD50.
The 35 is almost shoehorned into the space, although it does have airflow through from a cool spot and is exhausted into the cabin.

[OzePete]

Originally Posted by senormechanico

I'm in the PNW with cool salt water, but in the summer we go to Desolation Sound for a couple of months.
The water temps are in the mid 70's and air can get to 90 f.
All the while, we're carefully adding a can or two of 7up or V8 or similar.
Occasionally, the fridge seems to go into a continuous running and temp goes UP.
I shut it down for an hour and then it goes back to normal.
I have already added a cooling fan with adjustable snap disc thermo switch to the top of the compresser which exhausts the air to the cabin.

Oh, and I almost forgot, we have a separate homemade Aerogel freezer bag which we power with 5 lb Arctic Tundra blocks.
Every morning, we swap them into the refrigerator freezer compartment.
The fridge really gets a workout, but we've got enough solar.

Just to throw another log on the fire, would there be any advantage with a BD35/keel cooler system of ditching the cap tube for a TXV?
Just musing here...

Mate, altering your system from a capillary to TX valve will achieve nothing and you will have wasted about $120 buying a receiver, sight-glass and valve plus the cost of a mechanic etc.The clue to your problem is in your quote "Occasionally, the fridge seems to go into a continuous running and temp goes UP.
I shut it down for an hour and then it goes back to normal" It is likely that the system is 'flaking' due to air internally. Suggest you get it evacuated and re-gassed and I think it will work fine. Don't get too excited by the proponents of TX valves, they work well and so do capillary systems. There are advantages and disadvantages with both but funny how nearly 100% of the hundreds of millions of small fridge, freezers and air cons around the world are capillary fed.

[Typhoon]

Originally Posted by OzePete

Mate, altering your system from a capillary to TX valve will achieve nothing and you will have wasted about $120 buying a receiver, sight-glass and valve plus the cost of a mechanic etc.The clue to your problem is in your quote "Occasionally, the fridge seems to go into a continuous running and temp goes UP.
I shut it down for an hour and then it goes back to normal" It is likely that the system is 'flaking' due to air internally. Suggest you get it evacuated and re-gassed and I think it will work fine. Don't get too excited by the proponents of TX valves, they work well and so do capillary systems. There are advantages and disadvantages with both but funny how nearly 100% of the hundreds of millions of small fridge, freezers and air cons around the world are capillary fed.

Yes , I agree. almost 100% of home fridges and other domestic refrigeration equipment are Captube . They operate in a stable environment (72F = constant condensing temperatures ) and are cheap to manufacture.

Regards John

[Richard Kollmann]

Woodenboats, Feedback on Isotherm’s through hull condenser seems to be that if is installed in cockpit drain regular cleaning is easy with a long bottle brush. Boater on great lakes reported he is planning on replacing his Isotherm through hull condenser because keeping it clean in the lakes cold water is a problem. I wonder if boaters with these through hull units are aware of the zinc just inside the hull needs frequent inspection. If this through hull condenser is not operated in tropical waters compressor oil overheating failures are less likely. If operated in tropical conditions fan cooling of compressor may be required.

Cheechako, Same answers from boaters in tropical waters, disconnected Adler Barbour water pumps.

Vasco, In 2004 after receiving three water cooled EZ Kold condensing units with failed pin hole in cupronickel water tube I discussed problem with EZ Kold. I also informed many owners of water cooled E Z Kold machines as I could. Best advice I could give was to drain water from condenser and remove pump and hoses running system on air cooled condenser only. Once seawater is mixed with refrigerant complete system is junk. Ten years later after more condenser failures E Z Kold just before the shut down recommended pumping water from fresh tank through condenser. Although it was a little late PVC homemade water cooled condenser were fabricated and installed on units returned to factory for repair.. The air cooled portion of E Z Kold machines could still be operated indefinitely if water cooled portion was deactivated before water mixed with refrigerant..

Rich, You are correct refrigerant control cap tube versus valves and many other design variations that compromise or improve dependability of marine refrigeration need to be discussed. Your Cool Blue unit is simple, most energy efficient and is basic reliable refrigeration in the right application. If I get the time I will put together a variation of best design concepts for all application of icebox conversion refrigeration for cruising boats. Manufacturers today in all mechanical industries are over complicating their designs hopefully to achieve better results without considering after market maintenance do it yourself support. The old response of sending it back to our shop and we will repair it is a stupid answer for conversion refrigerators. Another manufacturer’s response is call a local repairman. We have all seen evidence on the web that when phoning manufacture doesn’t help solve refrigeration problems. The secret to a successful ice box conversion design is energy efficiency, reliability, with parts and service available in most ports around the world.

Rich and John, I am sorry but there are good reasons why capillary tube tubes are excellent refrigerant flow control devices and there are other reasons why and when Thermo Expansion Valves offer advantages. Correct refrigerant flow is important to keep liquid refrigerant phase change (superheat) to vapor while inside evaporator. Compressor manufactures set maximum and minimum refrigerant flow limits for each compressor design. Example small Danfoss BD compressor designs limits are difficult to stay within if standard TEV valves Btu limits are excessive. The main reason engineers prefer cap tubes over TXV and their refrigerant receiver tanks is to insure compressor’s long life with more accrete refrigerant flow control. Thirty years ago I worked with an engineer at Parker valves for six months to develop a reduction to standard wide open orifice expansion valves. Final solution was adding a fixed orifice before TXV on large holding plate systems. I used this orifice reduction method on mutable hybrid large five gallon holding plates and a single BD2.5 compressors back then. It is true that large holding plates systems and poorly designed standard evaporator systems are more efficient with TXV refrigerant flow control.

John, Your suggestion, ["With a TXV system you don't need a keel cooler or any other type of water cooling . You can't really just add the TXV to cap tube system they are completely different designs. You could use your compressor and controller if they are in good shape and build a system around them ."] Is a very unusually strange opinion..
Yes, Technautics use of expansion valve with large eutectic plates and aBD35 compressor running at low speed this might be the most energy efficient system available today. Cost of replacing correctly sized cap tube with a TXV and refrigerant receiver will far exceed the risks and benefit.

Jon, have you had to replace the Isotherm SP’s zinc if so how long do they last? Another question are all your boat's through hulls grounded?

My intent in this thread was to get boaters more involved in mobile boat refrigeration a dying industry. The eighteen True and False question based on a boater experience could be answer either way maybe True or maybe False. I also wanted to hear from technicians who are attempting to support varies small confusing over designed boat refrigeration systems and problems boat owners experienced.

[Typhoon]

Richard , sorry for the confusion, but we do this all the time . Also our systems are setup to run within the compressors designed parameters . They are not over worked and the TXVs do not hunt. They actually run very cool. Come by the Annapolis boat show in the spring and put your hand on one . We always have a system running steady during the show . As for effeciency . All our test data is on our web site .

Regards John

[a64pilot]

Originally Posted by ColdEh Marine

Also to address the heat put out by an air cooled unit you have to ask yourself, do you feel the temperature rise inside your boat when there is an extra person inside?

A person radiates around the same amount of heat as a Bd35/50 Danfoss compressor , but only when its running.

Regards John.

It was Gord a couple of years ago that posted that a person radiates about 100W
http://www.physlink.com/education/askexperts/ae420.cfm

Therefore if you assume a Boat fridge draws about 4 amps and has a 50% duty cycle, then it is adding the heat of 1/4 of the average human.
Not much when you think about it, and that is why it doesn’t heat a boat or a boats fresh water tank much at all.

[Rorzech]

Air cooled , less trouble, less head ache, less maintenance, less power,condenser can be made from copper or SS. You could run a condenser tube 5/16" SS around the toe rail to the bow or stern and back and the part that's in the shade will be the place that the condensing from gas to liquid will be taking place. Easy as pie !

[Rorzech]

In ref school they taught us for designing heat load for AC we added 350 BTU's /hr /person sitting in a room and 1000 BTU's /hr /person standing. Just saying.

[robert sailor]

Well I have to agree with Richard Kollmann on one thing and that is Isotherm's water cooling. We installed one when we were in the Med and used it there as well as later in the Caribbean. I was changing zinc' s more often than I expected and in order to keep it efficient I was cleaning it with a bottle brush regularly. I found that the whole system was running very hot at times and it really concerned me. When I was away from the boat and the system was shut down it took a full day and night for it to start operating properly. This last year I pulled the thruhull and added a radiator and a second small fan to blow heat from the area. I use about the same number of amps per day, its a simple system, no more diving, no more zincs and no more high operating temps plus when I restart the system it operates properly right away...life is good with a simple system.

[a64pilot]

Originally Posted by Rorzech

In ref school they taught us for designing heat load for AC we added 350 BTU's /hr /person sitting in a room and 1000 BTU's /hr /person standing. Just saying.

1 watt =3.42 BTU, so 100 W is 342 BTU per hour, which is extremely close to your 350 BTU per hour.
However I cannot explain the 1,000 from just standing?
http://ergo.human.cornell.edu/studen...condnotes.html

[MarkusK]

Originally Posted by Rorzech

In ref school they taught us for designing heat load for AC we added 350 BTU's /hr /person sitting in a room and 1000 BTU's /hr /person standing. Just saying.

I knew, someday, that keeping my old Carrier system design manual (part 1: load estimating) would come in handy. I will summarize table 48 – heat gain from people:

Seated = 350 Btu/hr
Standing = 450 Btu/hr
Walking slowly = 500 Btu/hr
Moderate dancing = 850 Btu/hr
Walking 3 mph = 1000 Btu/hr
Heavy work = 1450 Btu/hr

The above is based on 82°F space and is total heat. Sensible heat will be 50% or less.