Recent Posts

Pages: [1] 2 3 ... 10
1
Boat Refrigeration / Electronic Thermostats
« Last post by Richard on January 05, 2019, 03:11:42 pm »


The Idea that technology and technical support has advanced enough to replace a reliable mechanical boat refrigerator thermostats with an electronic thermostat is OK for the average armchair sailor. Blue Water Sailors may be miles away from their refrigeration system manufacturers expertise so either refrigeration is repaired or we feed the fish with our food in warm refrigerator.

It is always important to understand and plan for redundancy measures on each piece of important equipment on an airplane or yes also on a blue water cruising boat. The standard 12/24 volt boat mechanical snap action refrigerator thermostat is the same one that has been used reliably in home refrigerators for over 30 years with exceptional reliability. If you have an electronic thermostat at least carry a spare and know how to calibrate it. The refrigerator thermostat on the variable speed BD compressors is a simple OFF/ON two wire switch controlling one to five milliamps of power to another electronic switch inside compressors control module. Redundancy for faulty electronic thermostat operation in many cases has been achieved  by an override switch installed either at the compressors control module terminals C and T or on back panel of  electronic thermostats black box. When switch is closed compressor will run at low speed until emergency bypass switch is opened again allowing refrigerator to be operated manually.



2
Boat Refrigeration / Short Danfoss Engineered Module Service Life
« Last post by Richard on December 28, 2018, 07:11:55 pm »


Short Module Serviceable Life can be caused by how refrigerator was installed.

Danfoss has always experienced problems with electronic control modules on BD compressors. After ten to fifteen different Danfoss module models still randomly failures occur with no warning. If we exclude lightening strikes and corrosion due to water module failures seem to be caused by voltage spikes or heat.

Voltage spikes at module are not always visible with a meter and can be present on any boat. Unstable voltage is why the module must receive power direct from battery buss using correct size wiring, fuses, circuit breaker and switches that allow no voltage drop. When compressor is correctly wired to battery buss battery will absorb voltage surges like a very large electrical capacitor reducing module electronics failures. When refrigerator is powered from a branch circuit breaker panel any item in that panel can cause a damaging voltage spike when that item is powered up or powered down. Any relay when power is turned off sends a voltage spike back towards the source. Windless, power wench, generator start relays and even cabin light relays can damage refrigerator control modules if refrigerator is wired through a circuit breaker panel instead of main buss.

Module overheating maybe the primary reason for so many electronic control module failures. Through the years Danfoss has designed static air heat sinks on modules to conduct and radiate heat away from transistors and other components inside module. Module heat increases as compressor load (amperage) increases. Danfosss installation application data sheets have always assumed system designers and installers would insure compressor design power amperage limits were not exceeded. What you will find in the marine industry is the elimination of module and compressor cooling air along with higher than design compressor heat loads. Only Danfosss AEO modules have built in module cooling fans. Danfosss variable speed specifications for BD50 require an additional fan for cooling control module if compressor is to be operated at maximum capacity (3500 rpm). All of the following conditions can cause module overheat failures; High condenser cooling temperatures, Repeated attempts to start do to an overloaded compressor, First box temperature pull down in a hot climate, System ambient temperatures above 105 degrees F, and too large or poorly designed holding plate evaporator coils. Failure to maintain good cool flow of condenser air, a normal maintenance item, should not be overlooked as cause of module failure.
3
Boat Refrigeration / DIY Smart Non Destructive Refrigeration Knowledge
« Last post by Richard on December 19, 2018, 02:19:05 pm »
DIY Smart Non Destructive Refrigeration Knowledge
________________________________________
.

I have been asked many times over the last 30 years to recommend a repair person experienced in repair of pleasure boat refrigerators. These days there are over 100 different fractional horse power 12 volt refrigeration configurations in boats under 50 feet. To find a person with experience on all small refrigeration units is not possible. There are no licenses available to qualify a person to accomplish a repair to a malfunctioning small boat refrigerator. Manufacturers specific training on each model or previous experience is necessary to repair these small 12 volt units. Each week I see where a so called HVAC trained technician or an Automobile AC mechanic screw up a good small pleasure boat refrigeration unit do to their lack of the right knowledge.

I have spent sixty of my eighty years assisting mechanics and operators of equipment in Do It Yourself troubleshooting and repair. Most of the time DIY is the only or smartest way to keep something operating. If a boat owner understands a few simple facts he or she can save on costly repairs and in many cases avoid purchasing a new refrigeration unit. Before allowing anyone including yourself to touch a malfunctioning refrigeration system powered by a Danfoss 12/24 volt BD compressor you should know these facts:
If This BD Compressor does not run it is because the control module sees electrical current is out of normal limits and to protect compressor from an internal failure control module  stops compressor. After electronic control module detects amperage loads or voltage out of predetermined limits it will stop compressor from running until problem is corrected. After stopping compressor module will attempt a restart every 20 to 40 seconds to determine if problem is corrected.
Most important trouble shooting item to remember about Danfoss BD compressors is, If compressor will not run problem is electrical. Only if compressor runs with little or no cooling it is safe to assume refrigerant volume or its flow is the problem..
Danfoss BD compressors manufactured after 1995 are three phase variable speed allowing balancing of system performance reducing energy consumption. These compressors are identified by model numbers BD35, BD50 and BD80 they also have ability to identify problems by a troubleshooting LED fault code if compressor fails to start up and run. The trouble LED will not flash if the thermostat fails to turn power on to compressor. Trouble LED will or will not show all problems. There are things you should know about Danfoss BD compressor refrigeration that most repair people dont know about your Adler Barbour , Frigoboat or other type refrigeration units. This applies to Danfoss BD compressors installed after 1995. Troubleshooting the newer Danfoss variable speed BD compressors when equipped with troubleshooting LED is easy if the following information is understood:
LED will not signal if there is no power to Danfoss Control module.
LED will not signal if thermostat circuit is open.
LED will not signal if compressor is running continuously with poor or no cooling.
LED will not signal if system is low on refrigerant, compressor will run with little or no refrigerant and still no LED signal.
LED will flash 3 times every 4 seconds if there is too much refrigerant in system or poor condenser compressor cooling.
On Adler Barbour CU100 and CU200 LED will not flash when compressor stops do to a problem inside the add on stainless box. This seems to be caused by poor solder connections to fuse holder or cracked printed circuit board. See my TECH TIP #1 on my web site for circuit board picture and how to bypass problems with this circuit board.
If no one has tampered with refrigerant and refrigerant flow is blocked, compressor will not stop nor will LED flash on this type system. Common problem on Frigoboat keel cooler systems when refrigerant flow is restricted. Adding refrigerant will only cause additional problems. Ask Frigoboat US for help.
If there is too much refrigerant or contaminated refrigerant compressor will not start or run signaling with Three LED flashes.
Unlike automobile computers Danfoss electronic modules micro chip only has space for one trouble memory. Because only one memory is all that can be stored it is possible for a second problem to mask over signal covering up the first LED signal code. Say the first signal is do to a low voltage giving a one LED flash every 4 seconds, compressor will stop and try to restart in 20 to 40 seconds. If refrigerant pressure has not equalized in this short off cycle a restart attempt can cause a three LED flash signal indicating an overload. When a three LED flash is indicated always confirm it by turning refrigerator power off and while watching LED turn power back on. The first seen signal code is where the problem is.
A faulty ground between module and main battery buss has been known to signal 3, 4, and 5 LED codes.

Low or no refrigerant at all will not prevent this compressor from running.
Because this compressor is silent the only way to confirm it is running is it will be warm to the touch after it has been running for 20 minutes or longer.

Very rarely will you find a service tech who will take the time or be able to service these small units with refrigerant correctly because variations in ambient air or water temperatures as well as system design affect refrigerant charge.
Service technicians and helpful friends rarely practice non destructive testing when they first approach a refrigerator problem. One way to know if someone does not know what he is doing is if he wants to check refrigerant pressure. Tampering in any way with refrigerant on these small systems that may hold only from 3 to 4 ounces of refrigerant generally leads to disaster us conditions at some point in the future.
It is important to know that small icebox conversion units are not mass produced in a quality controlled atmosphere like standard home refrigerators. Rarely are their filter/dryers large enough to capture additional moisture over what was generated in manufacturing process. There is always a risk of moisture contamination when tampering with servicing ports. Even purging gauge sets with refrigerant before will not eliminate all osmoses imbedded moisture from gauge set hoses.
Danfoss BD compressor Ice box conversion refrigeration systems will not lose refrigerant if properly designed and installed correctly. The exception to this fact will be when line connecter O rings are used as final refrigerant seal.
     
4
Boat Refrigeration / Thermostat short cycling
« Last post by Richard on December 17, 2018, 12:36:24 pm »


Richard -My AB compressor runs great and cycles regularly with no apparent problems, but the temperature in the freezer never gets below 20F.  My sense is that the compressor is doing everything its asked to do but the t-stat is not telling it to run long enough each cycle, telling it thats good! when 20 is reached.  Is there a way to adjust the t-stat?  Is it possible that I have a refrigerator t-stat in my freezer?  Lastly, what AB model number should I look for to replace this one with a true freezer t-stat?  Thanks!
JD

ANSWER
The thermostat has a temperature sensing tube that tells thermostat when to run compressor. This sense tube on AB units should only touch evaporator at its end if it touches any other cold spot compressor will begin short cycling.
 
The correct AB temperature control to evaporator contact of temperature sense tube is to have the last 5 inches bent in to a U shape and is clamped at the evaporator space provided with two screws. The less sense tube touching evaporator the longer compressor will run and the colder the evaporator will get. 
 
If you want the compressor to freeze every thing in box then buy a freezer replacement from www.Rparts.com.
 http://www.rparts.com/product_info.php?cPath=84_13_17_42&products_id=112&osCsid=alluutoemnrpc0ktlev6ivemd6
5
Boat Refrigeration / Pleasure Boat Refrigeration Technical Services from Hell
« Last post by Richard on December 17, 2018, 12:17:38 pm »

________________________________________
I began my mechanical training in 1949. I took classes in aviation maintenance and engineering. Back then general experience in a wide range of technical subjects was sufficient enough to practice a mechanics trade. In those days there was an overlap in experience skills between Mechanics, Technicians and Engineers. Training and gaining experience then was less complicated as equipment hardware used common components and software controlled electronics was not involved in daily maintenance or engineering. One of the biggest challenges affecting mechanics, technicians and servicing personal today is a change in defining what is Repairable or Expendable. It was not too long ago that kitchen appliances, radios and lawnmowers were repairable. Do manufacturers plan for refrigeration design obsolescence in order to continue their replacement market or is it just an accident that their products are obsolescent because they are not maintainable and therefore must be considered expendable. When an automobile dealer mechanic can not correct a cars problem he links the cars computer to the manufacturers engineering department computer by way of the internet or asks the manufacturer for help. I find there are no means of contacting specialists in repair techniques on pleasure boat refrigeration. When you deal with as many pleasure boat refrigeration problems as I do, you will realize the job shops that build 12/24 volt refrigeration units are not interested in after market support. Here is how I define what should be an acceptable after market support strategy programs for all pleasure boat refrigeration manufacturers and US distributors if units are imported:
   Must have an available experienced Technician to answer technical questions with reasonable accuracy about the products you sell.
   It is a mistake to purchase an icebox refrigeration unit from a manufacturer that does not have their Maintenance servicing repair manual available on their web site.
   These companies that design or market their products know something about the systems weak points that could help owners/operators keep their refrigerators running longer. Why not post on the web, Service Bulletins or Technical Tips?
   Reliability engineering analyses is a simple tool developed from questions and technical data received from customers. Taking corrective action based on reported problems is a necessary strategy if a company wants to stay in business.
   Probably the poorest strategy for a distributor or sales person to deal with on a non standard refrigeration unit is to advise a boater to call a local refrigeration mechanic when they know this may damage the units further.
   Probably the most discouraging advice a boater can receive is its, time to replace your complete system, because no one is interested in helping you with advice needed to repair the present system.
We have seen several pleasure boat refrigeration industries slowly disappear or be forced to diversify into other products because of what appears to be unproductive system design flaws and poor aftermarket strategies. SeaFrost and Technautics may be the only older boat refrigeration companies staying true to their product line with responsibility for After Market support over the years.

Many times normally maintainable boat refrigeration is bastardized to a point that when cruising it is not possible to make repair without the person that design it. When out of range of conventional aftermarket odd replacement parts, accessories or without enhanced repair knowledge boaters have to do without their refrigerator. Basic Danfoss air cooled refrigeration hardware is more apt to be available in most areas of the world. Add on gadgets that do little to enhance performance like electronic thermostats, water cooling condensers, keel coolers or other electronics will all put operating refrigerators reliability at risk.

Boaters today must wonder why 30 year old 12 volt Danfoss BD compressors perform well in systems made by the original Adler Barbour company, Electric Iceman company and a few others. The newer Danfoss BD 12/24 volt air fan cooled compressor systems will only last another 30 years if unproductive gadgets are omitted. Frigoboat BD water cooled compressor systems are replaced early because of refrigerant troubles. E Z Kold systems are replaced because of seawater interring the compressors refrigerant. Many Danfoss BD compressors are replaced even systems because a Service Technician or someone calling himself a Refrigeration Engineer mistakenly advises that BD compressor rotor is locked up. Other BD compressor failures reported by Technicians From Hell were replaced because someone tampered with refrigerant or added too much refrigerant thinking this is cause for compressor replacement. Lack of experience, knowledge and incorrect advice from the system manufacturers representatives, along with absence of correct manual information and lack of helpful service bulletins are why experienced local mechanics are no longer interested in servicing small 12 volt refrigeration. Locked compressor rotors are common on large hermetically sealed compressors and even water cooled BD compressors but are extremely rare or never occur on air cooled BD Danfoss compressor units.

I received three emails in one month of service personal in Michigan advising boat owners that their Danfoss BD compressor needed to be replaced, my response is always the same. If this is an air-cooled unit, I inform them that there is an electrical problem with their system and warn them not to allow anyone to touch the refrigerant or touch its service ports. Usually this advice is always too late. Identifying trouble area must be accomplished first by Non Destructive testing before tampering with refrigerant. I can not tell you how many times mechanics will say a Danfoss BD compressor will not run if low on refrigerant, This is FALSE,. BD compressors will run even with no refrigerant in them. But if there is too much or contaminated refrigerant the electronic control module will detect high amperage and prevent compressor from running.

A few months ago I received an email that one of these mechanics from hell replaced a complete Danfoss BD electronically controlled compressor system because the compressor would not run. When the new unit would not run either, boat owner was told to contact me for help.
Replacing a system without following non destructive adequate testing first to verify the actual cause of problem is a mistake. Replacing a compressor or a complete system is as destructive as any test I know of. After boat owner spent $1000 or more I advised him that problem was and is still in the boats electrical system bad circuit breaker, old wiring, or bad wire connection.

Operators of 12/24 volt refrigeration units powered by a Danfoss BD compressor must understand that there are almost no technicians that understand modern hermetically sealed electronic compressor protective microprocessor control systems. The correct approach to finding and solving problems on one of these delicate units must be with simple non destructive tests. Anyone attempting to troubleshoot a Danfoss compressor system equipped with trouble LED codes must be aware that it will be necessary to interrupt code flashes yourself as manufactures manuals may be not be correct. Example, Locked Compressor Rotor or System over load, a code of 3 LED flashes I have never found it to be a Locked Rotor on an air cooled Danfoss BD compressor. In my library of Emails and forum posts I found 61 times where Danfoss BD compressor or system replacements advice was not supported by quantified facts. Three flashes of troubleshooting LED indicates a high amperage spike and very unlikely caused by a locked rotor.

For many years small refrigeration units manufacturers did not provide servicing ports to add or remove refrigerant. Adler Barbour and most home refrigerator manufacturers knew of the problems if their units could have refrigerant charge tampered with so their
units were designed without servicing ports. After the 1996 Clean Air Act all systems containing refrigerant must have a servicing port in order to remove and recover refrigerants.
6
Boat Refrigeration / Selecting Correct Refrigeration For Your Boat
« Last post by Richard on December 17, 2018, 10:25:59 am »

It is obvious that good boat refrigeration is viewed differently by each of us. There are those that are satisfied with only refrigeration enough to produce box temperatures equal to that of ice melting 45 to 60 degrees F. Other boaters want refrigerator/ freezer box temperatures just low enough to slow down growth of bacteria. Cruising and live aboard boats prefer to have the ability to make ice and store frozen food. Since preferred box temperature figures are always arbitrary the buyer should be aware of their preferred temperature needs as the seller might be happy with a box temperature in the 45-60 degree range. In one Four Star rating system on the web +21 degrees F will maintain food eating taste quality in your boats box for only a week.
   Minimum temperature = −6 C (21 F). Maximum storage time for (pre-frozen) food is 1 week
   Minimum temperature = −12 C (10 F). Maximumstorage time for (pre-frozen) food is 1 month
   Minimum temperature = −18 C (−0 F). Maximum storage time for (pre-frozen) food is between 3 and 12 months depending on type (meat, vegetables, fish, etc.)
There are a lot of theories in the application of mobile refrigeration for pleasure boats but little quantified data on performance for your one of a kind boat box. The reason for this is that there are no two boats identically the same. Nor are there standards in reporting performance data like box size ambient temperatures, box interior temperatures through out areas of boxes, or equipment configurations, and daily power consumption data.

Anyone trying to recommend icebox conversion refrigeration for mobile refrigeration needs to study each application and intended use by the boat owner while disregarding creative advertising by sales people. You will not easily find in Mechanical Engineering Hand Books or ASHRAY engineering folders information on pleasure boat refrigeration. The ice box charts used to calculate insulation versus Btu conductivity that we all have used for document fillers are worthless. A pleasure boats cruising refrigerators daily heat load increases as the crews demand for cold liquid and amounts of drink ice increases, also daily product in and out of the box must be added when calculating daily Btu power requirements. If present insulation is free of moisture an R value of 20 is OK for refrigerator insulation in a cool climate and R30 is OK in the warm tropics. With 12 volt ice box conversions in tropical climates it is difficult to have freezer temperatures low enough for long extended cruises.


When I look at an installation application concept for a cruising boats refrigerator I use a basic guide:
   Determine worst case planed cruising climate for this refrigerators application.
   Smart engineering with new variable speed BD compressors are designed for their running time to be less than 50% duty cycle. Optimum energy efficiency is achieved when desired box temperature can be maintained at the slowest compressor speed and still have less than a 50% compressor running duty cycle.
   Box size and planed use will define size of a refrigeration system. Boxes smaller than eight cu ft can be efficiently cooled to refrigerator temperatures in warm climates with Danfoss BD50 compressor/condensing units. Boxes smaller than 4 cu ft are more energy efficient using a BD35 compressor.  Refrigeration capacity larger than eight cu ft boxes in tropical climates will require compressors larger than a single Danfoss BD50.
   Freezers in tropical climates with Danfoss BD compressors are limited to 4 cu ft. Even in winter a BD50 compressor system in tropics can be expected to run most of the day at max Rpm to maintain desired freezing temperatures below +10 degrees F.
Most of the sail boaters I meet have plans, at some point, to cruise into tropical waters south of Latitude 26N. Twenty eight years in boat refrigeration has convinced me to develop a program of how to select refrigeration system capacity for pleasure boats. This program designs for worst case conditions then allows anyone to reduce projected Btu and amperage worst case for their cruising area conditions by a simple formula. After following the exercise on my wed site slide show the worst case Amp and Btu totals can be lowered by 2% for each degree of seawater temperature below 89 degrees. Example using my worst case water temperature always of 89 degrees and actual water temperature where the boat is to be operated say at Latitude 30N in the spring with a water temp of 55 degrees there is a reduction of 34 degrees times 2% = a refrigeration energy reduction of 68 % from the worst case calculation.

Of course desired box temperatures will depend on many things:

Equipment selected
Avoiding experimental unproven components
Simplicity
Satisfied costumer Experience with this design.
If there is enough variable power to support this refrigeration.
Reasonable amount of Box Insulation
Selecting Manufacturer based on a dependable design at the best price.

     
7
Boat Refrigeration / Frigoboat Keel cooler systems poor performance
« Last post by Richard on December 10, 2018, 02:57:09 pm »

E Mail
We have been cruising our Bavaria 46E in mexico for the past 7 months and we have exposed some refrigeration deficiencies.  I was hoping you could assist me or at least point me in the right direction.  I have read a multitude of forums and looked through your website info and have determined that I may have a blockage in my system.
We had our stock Frigoboat system refrigeration upgraded by removed our tiny evaporator shoebox freezer and built us and installing a new evaporator box capable of freezing more that a couple burritos or hot pockets.
I observed the 'professional' commit some heinous acts - first, screwing the new evaporator box to the bottom of our refrigeration box - exposing it to future moisture and compromising our insulation.  Second, he cut off the old connectors and soldered them to the new evaporator box. and third, he only evacuated the the new system for 15 minutes before filling it with R134a - inverting the bottle and injecting frozen refrigerant directing into the compressor, and causing an immediate compressor fault to boot!  after all that, the system seemed to run fine but i learned my insulation was quite wet - which required additional attention.
So, we've been running it for a few months now while sailing south into warmer waters and we have noticed that it just doesnt get very cold anymore.  we needed to defrost a few times due to its efficiency, but now it barely frosts half of the evaporator.  I put some gauges on it to determine if it meets your baseline pressures - 6 to 8 psi on lowside and 110 to 120 on highside after 10 minutes - the low was good, but the high was over 150psi and i'm just not sure how to adjust that, or if that is indicative of another problem i may have...
Another tidbit of info is that upon initial compressor startup after an off cycle, the return line from the evaporator flashes quite cold causing it to sweat.  this includes the quick disconnect fitting and the filter and up to the compressor intake.  After a couple minutes this condition is gone. 
And my K50F compressor gets super hot, sometimes up to 150 degrees F.  I have installed the "Stainless Lobster" thermostat and control system and i have experimented with low and high compressor speed setting.  i still have the original mechanical compressor with the smart speed controller but no longer use them. 
Oh, and the capillary tube what was installed on the new evaporator box is remarkably skinny, like less than 1/8" - it is soldered to a larger copper tube and wrapped around the even larger return line about 30 times before it is then soldered to the larger evaporator inlet tube.
Anyhow, if you are able to provide me some guidance, id really appreciate it.
I am planning to attempt a long term dehydration routine tomorrow - hoping to remove any possible blockage or contamination - but thats all i can think of. apart from buying an Engel Box, or new system.

Cheers,
RF


Answer Frigoboat Keel cooler systems poor performance:

1.   After replacing evaporator and cap tube cruising in Mexico refrigerator know not cold enough.
2.   Normal low suction pressure near normal 6 to 8 psi.
3.   High liquid refrigerant pressure too high  150 psi.
4.   Compressor temperature of 150 degrees F over time causes the compressor oil to thicken reducing refrigerant flow. When oil is contaminated in the beginning or capillary tube is incorrect size suction pressure is reduced so correction made is to add refrigerant to increase flow and at the same time this will raise high pressure and compressor temperature.
5.   There are reasons why high pressure is so high; Keel cooler outside boat needs cleaning, Incorrect Cap tube size, Cap tube wrapped more than 10 times around low pressure tube or a restriction caused from soldering or build up of soldering flux somewhere in system.
6.   
Recommendation:

Think seriously about buying a portable Engel refrigerator/Freezer because if you do not fix this problem the compressor heat will destroy the complete system as it has done on other Frigoboat systems.

If there is a refrigerant restriction it will need to be corrected.

It sounds like you are looking for a refrigerant flow restriction or a lack of cooling by keel  cooler condenser. The temperature of refrigerant line coming out of keel cooler should be less than 115 degrees F.
 Anywhere there is a restriction to flow that spot will cool and in most cases frost or condensation will present. After system has run one hour or more look every where for cool or frosted spots.


8
Boat Refrigeration / AEO Compressor Speed Controller
« Last post by Richard on December 10, 2018, 10:42:30 am »


E Mail Question, I have a Danfoss BD 80 compressor with a 101N290 electronic control module is the speed automatically changed?

The 101N0290 module is for BD80 compressor running at a preset speed and is not an AEO module. The 101 N0280 module is designed for the BD80 AEO.
If  you would like to know what speed your present 290 module is running compressor at disconnect thermostat wires from module and measure ohms of resistance back through thermostat. A reading of 203 ohms indicates compressor is running at 2500 Rpm. 451 ohm 3100 Rpm. 867 ohms 3800 Rpm and 1700 ohms 4400 Max Rpm.

There are several add on speed controllers that control speed by compressor cycle times. but my favored one  is the Danfoss AEO. Isotherms ASU monitors temperature to determine compressor speed. There is a difference in AEOs between the Smaller BD compressors and your BD80. When thermostat starts a BD80 with 101N0280 AEO it will run at 3250 rpm and then speed will be ramped up every 9.4 minutes for 48 minutes reaching 4400 Rpm. The next time thermostat starts it runs compressor at 300 Rpm less than Rpm where it stopped. This off and on cycling finally reaches energy optimization where each thermostat OFF cycle is extended to 24 minutes. The slower compressor runs the more energy efficient it is.
9
Boat Refrigeration / Act like you are the design application engineer.
« Last post by Richard on December 10, 2018, 10:21:31 am »
Act like you are the design application engineer required to select a typical Icebox Conversion Refrigeration unit for a friend.

I would like to hear from a number of experienced Boaters what they believe the real difference is between any two totally different Icebox Conversion Refrigeration units. The box to be used is 5.6 cubic feet 24 in wide 20 in long and 20 in deep. with three inches of insulation and a 16 by 20 in top lid opening. The ambient temperature where box is located will average 80 Degrees F. 24 hours a day. 
Special requirements for this coastal cruising boat with two people on board are:
   Low daily power consumption
   Low reasonable cost of refrigeration unit
   Condensing unit design to adapt to most locations in a boat.
   Simple installation.
   DIY maintenance
   Because mobile refrigeration must be repaired locally any refrigeration trained technician should be able to repair this refrigeration system.
   Replacement parts and components are available within a day or two and hopefully there are no proprietary parts that can not be replaced by a similar part. As experienced in the past boat refrigeration companies go out of business and their after market support goes with them. How long are the replacement parts going to be available?
    It is difficult to achieve normal refrigerator zone temperatures in small refrigerated boxes; Drink cooler, Refrigerator section and Freezing section.
   Small icebox conversions for cruising boats should at least have a dual temperature box.
   Standard mechanical thermostat that can be set to control temperature in freezing section without freezing items in refrigerator section.

I have selected a well known Nova Kool basic icebox conversion refrigeration LT201 system and its twin plate RT 6 box evaporator. Nova Kool still uses the popular Danfoss engineered compressor Yes, I know this compressor is now made in China but so are the other five off brands of look alike 12/24 volt compressors.

What ice box conversion refrigeration and its components will you recommend youre your boating experiences and what added improvements would you add to improve the above requirements for this size box.
10
Boat Refrigeration / The Success or Failure of Pleasure Boat Refrigeration Companies
« Last post by Richard on December 06, 2018, 10:35:36 am »

I have seen so many changes in pleasure boat refrigeration in the last thirty years, start up companies with new design ideas that could not stand the test of time are diversifying to other product lines or going out of business.. Boats of forty feet and less generally were not designed to support energy demands of mechanical refrigeration. Refrigeration is a process of moving heat from one location to another under controlled conditions. Companies that are successful in the boat refrigeration business need to be aware of the small market for their products. If a companys business plan does not satisfy each customer with; guaranteed reliability, after market support and available access to parts anywhere experience shows that these businesses will fail.

Some pleasure boat refrigeration companies appeared to have failed because of failure to recognize their units design or manufacturing flaws and did not take corrective action until it is too late. A major fault in many company business plan is in over use of creative smoke and mirrors indicating exceptional overall performance. You will always get old untruth comments in response when refrigeration is not performing as advertised from a salesman indicating; Box insulation R value is not good enough, You need water cooling, You need an expansion valve instead of a cap tube, Holding plates store energy and are more efficient than standard evaporators, What you need is an electronic thermostat. If you believe any of the above responses are correct solution maybe you would like to buy a bridge over the ICW.

As I follow boat refrigeration comments on the web it is more Dj vu phenomenon of boat refrigeration creative smoke and mirrors advertising all over again and another short term business plan in process.   Is Randys Cool Blue refrigeration unit still the exceptional breakthrough in small refrigerated icebox conversions for boats or as the new owners marketing plan says (One more year of High School for my Son and then it's back to the land of Mexico for cheap Tacos baby..)

A marketing study once claimed one satisfied costumer will increase sells by three and just one dis-satisfied customer will discourage eleven customers from buying the product.

Remember when a salesperson claims his recommended system costs more because it is more efficient it probably will not perform as well as salesperson claims in your application. It is also important to realize refrigeration means different things to different people. After it is installed is it going to be a 50 degree F drink cooler, a 33 to 36 degree F refrigerator or a combination zero degree freezer 36 degree F refrigerator. In very warm climates freezer will require a total insulation R value of at least R30 totally dry insulation or R20 in normal 70 to 80 degree climates. In spillover applications the divider must be at least insulated to R20 with some type adjustable mechanical control of refrigerator side box temperature.

It is also important to know that in warm climates 50% of the energy consumed is by product through put remember this will decrease refrigerator performance and increase energy consumed.

Increasing Insulation from 3 to 6 inches outside the box in hot climates will improve performance by 15%. Adding insulation inside a refrigerated box will greatly improve refrigeration performance mainly because box is smaller.
Pages: [1] 2 3 ... 10