1. AmelYachtOwners | Main
  2. Topics

[Amel Yacht Owners] Frigoboat re-charging

Mohammad Shirloo
 

Hi Paul;
 
The following is an article that I had run into when I was debugging an issue with our refrigerator. It is on Coastal Climate Control's website. As mentioned on the forum, they seem to be proficient in what they do and therefore I would consider the source reliable.
 

R134a Recharge Guidelines

 

R124a cannisterThere is much talk and discussion in certain forums about how to determine the correct refrigerant charge level for a capillary tube refrigeration system, but there is only one, simple method that will result in the perfect charge in a Frigoboast system; the frost-line method. Pressures and current draw can be monitored to confirm that these are within expected limits, but there is no better way to guage the refrigerant level than with the frost-line method.

Frigoboat R134a charge guidelines

General
The following is intended to be a guide for a boat operator with average mechanical skills. It will describe what symptoms to look for in a correctly charged Frigoboat system so that an evaluation can be made as to whether service is required. No refrigerant gauges are necessary for this evaluation, and their use is required only for major repairs and for evacuating the system.

Warning!
Never use, or allow a technician to use, anything other than pure refrigerant R134a in a Frigoboat system. Cans of refrigerant R134a with additives must never be used, nor must stand-alone additives be introduced into the system. These additives include but are not limited to: leak detecting fluid, leak stopper, dye, extra oil, conditioner, etc. Serious damage can result from the use of such products, which are designed for use only in auto air conditioning systems.

Symptoms of correct and incorrect charge

Correctly charged system
The Frigoboat systems are capillary tube systems, and require a precise refrigerant charge to work at maximum efficiency. Too much or too little refrigerant will result in a systems that will have some cooling effect, but will not be working to it’s full potential. In a Frigoboat system, the temperature of the evaporator is directly related to the amount of refrigerant in the system. There should be enough refrigerant in the system so that the last of the liquid is evaporating back to a vapor at the very end of the evaporator, and just as it enters the suction tube back to the compressor. After running for a time, there should be a slight coating of frost all over the surface of the evaporator, and there should be no condensation or frost on the exposed section of copper tube back to the compressor, and no condensation on the compressor itself. If the system has been installed correctly, the short length of insulation supplied with the system should be positioned on the copper tube starting where it exits the refrigerated box. No other insulation is required, and any extra that has been installed will only cause the system to run at less than maximum efficiency and may conceal symptoms of an overcharge. This short length of insulation is installed to prevent any condensation that may occur as the cold tube leaves the refrigerated box and is exposed to hot, humid air. In a properly charged system, there should be a “tinny, gurgling” sound from the evaporator.

Slightly undercharged system
If there is too little refrigerant in the system, it will have evaporated back to a vapor before it reaches the end of the evaporator. Some of the surface will have a coating of frost, but from the point where the refrigerant has turned all to vapor, the surface will be cold and sweating. The frost begins at end of the capillary tube, where the liquid refrigerant is fed into the evaporator. The evaporator will probably sound the same as a properly charged system.

Seriously undercharged system
If the system is seriously undercharged, the refrigerant may exist in the system only as a vapor, and so there will be no frosting on the evaporator, just a slight sweating and coldness to the touch. In this condition there will probably be a constant hissing sound from the evaporator. This sound is important in identifying if the system is undercharged or overcharged.

Slightly overcharged system
Too much refrigerant in the system will result in liquid still evaporating back to a gas past the end of the evaporator and inside the tubing going back to the compressor. This means that there is still some of the refrigeration process going on inside the tubing, and there will be a build-up of frost or ice on the exposed section. If additional insulation has been added, it may be concealing this symptom and should be removed. The evaporator may appear and sound normal, but will be at a higher temperature than desired, resulting in longer than expected run times.

Seriously overcharged system
If so much refrigerant exists in the system that it raises the temperature of the evaporator above 32 deg F, the surface will only be sweating and cold to the touch, resembling an undercharged condition. But the copper lines leading back to the compressor, and maybe even the compressor itself, will also be cold and sweating, and there will probably be a sound similar to a mountain stream coming from the evaporator. This is a potentially damaging condition as liquid can reach the compressor where it can damage the valves, since refrigeration compressors are designed to compress gas only.

 
 
 
Respectfully;
Mohammad and Aty
B&B Kokomo
Amel 54 #099
 

From: amelyachtowners@... [mailto:amelyachtowners@...]
Sent: Saturday, March 31, 2018 3:14 PM
To: amelyachtowners@...
Subject: [Amel Yacht Owners] Frigoboat re-charging

 

Hi all,

Would anyone know where I can find an idiots guide to re-charging a friogboat fridge whcih uses R134A refrigerant?

Cheers,
Paul
Ya Fohi - Amel 54 #98
ya_fohi
 

Mohammed,

Thanks. I have in fact comae across this and it does seem like a good diagnostic guide but it does not tell me how much refrigerant to put in.

Cheers,
Paul
Ya Fohi - Amel 54 #98
greatketch@...
 

Capillary systems are notoriously difficult to get a correct charge with.

Here is Coastal Climate Control's take on the issue...


Bill Kinney
SM160, Harmonie
Moraine Cay, Abacos, Bahamas
ya_fohi
 

Thanks Bill. I did finally find some instructions here

https://www.sailmagazine.com/diy/recharge-your-refrigerator-2

Only thing is that this is for a Danfoss system. I just need to identify the low pressure connection on my Frigoboat system.

Paul
Ya Fohi - Amel 54 #98
Mohammad Shirloo
 

Paul;

If I recall correctly, the amount of refrigerant is extremely hard to adjust in the field. This was due to the small amount of refrigerant in the unit. Again, if memory serves, the article said that it needs to be done in a very controlled "lab" type environment at the factory.

The main take was, Do not allow any "A/C expert" add refrigerant in the field.

Respectfully;


Mohammad

On Mar 31, 2018, at 5:22 PM, sharongbrown@... [amelyachtowners] <amelyachtowners@...> wrote:

 

Mohammed,

Thanks. I have in fact comae across this and it does seem like a good diagnostic guide but it does not tell me how much refrigerant to put in.

Cheers,
Paul
Ya Fohi - Amel 54 #98
Mark & Debbie Mueller
 

The low pressure tap connects to the compressor case directly.  Mine is located on the dome of the compressor. 

Mark Mueller
A54 - 68, Brass Ring
Ft. Lauderdale
John Clark
 

Mohammad,
  I was going to write a respose based on recharging my unit but this is way better.  One point I would add is that if one is not using a set of refrigeration gauges to make sure to connect the 134 can to the low pressure side.  This is the suction side of compressor and will likely be cool or cold.

John
SV Annie. SM37
Great Guana Cay Exuma.

On Sat, Mar 31, 2018, 6:51 PM 'Mohammad Shirloo' mshirloo@... [amelyachtowners] <amelyachtowners@...> wrote:
 

Hi Paul;
 
The following is an article that I had run into when I was debugging an issue with our refrigerator. It is on Coastal Climate Control's website. As mentioned on the forum, they seem to be proficient in what they do and therefore I would consider the source reliable.
 

R134a Recharge Guidelines

 

R124a cannisterThere is much talk and discussion in certain forums about how to determine the correct refrigerant charge level for a capillary tube refrigeration system, but there is only one, simple method that will result in the perfect charge in a Frigoboast system; the frost-line method. Pressures and current draw can be monitored to confirm that these are within expected limits, but there is no better way to guage the refrigerant level than with the frost-line method.

Frigoboat R134a charge guidelines

General
The following is intended to be a guide for a boat operator with average mechanical skills. It will describe what symptoms to look for in a correctly charged Frigoboat system so that an evaluation can be made as to whether service is required. No refrigerant gauges are necessary for this evaluation, and their use is required only for major repairs and for evacuating the system.

Warning!
Never use, or allow a technician to use, anything other than pure refrigerant R134a in a Frigoboat system. Cans of refrigerant R134a with additives must never be used, nor must stand-alone additives be introduced into the system. These additives include but are not limited to: leak detecting fluid, leak stopper, dye, extra oil, conditioner, etc. Serious damage can result from the use of such products, which are designed for use only in auto air conditioning systems.

Symptoms of correct and incorrect charge

Correctly charged system
The Frigoboat systems are capillary tube systems, and require a precise refrigerant charge to work at maximum efficiency. Too much or too little refrigerant will result in a systems that will have some cooling effect, but will not be working to it’s full potential. In a Frigoboat system, the temperature of the evaporator is directly related to the amount of refrigerant in the system. There should be enough refrigerant in the system so that the last of the liquid is evaporating back to a vapor at the very end of the evaporator, and just as it enters the suction tube back to the compressor. After running for a time, there should be a slight coating of frost all over the surface of the evaporator, and there should be no condensation or frost on the exposed section of copper tube back to the compressor, and no condensation on the compressor itself. If the system has been installed correctly, the short length of insulation supplied with the system should be positioned on the copper tube starting where it exits the refrigerated box. No other insulation is required, and any extra that has been installed will only cause the system to run at less than maximum efficiency and may conceal symptoms of an overcharge. This short length of insulation is installed to prevent any condensation that may occur as the cold tube leaves the refrigerated box and is exposed to hot, humid air. In a properly charged system, there should be a “tinny, gurgling” sound from the evaporator.

Slightly undercharged system
If there is too little refrigerant in the system, it will have evaporated back to a vapor before it reaches the end of the evaporator. Some of the surface will have a coating of frost, but from the point where the refrigerant has turned all to vapor, the surface will be cold and sweating. The frost begins at end of the capillary tube, where the liquid refrigerant is fed into the evaporator. The evaporator will probably sound the same as a properly charged system.

Seriously undercharged system
If the system is seriously undercharged, the refrigerant may exist in the system only as a vapor, and so there will be no frosting on the evaporator, just a slight sweating and coldness to the touch. In this condition there will probably be a constant hissing sound from the evaporator. This sound is important in identifying if the system is undercharged or overcharged.

Slightly overcharged system
Too much refrigerant in the system will result in liquid still evaporating back to a gas past the end of the evaporator and inside the tubing going back to the compressor. This means that there is still some of the refrigeration process going on inside the tubing, and there will be a build-up of frost or ice on the exposed section. If additional insulation has been added, it may be concealing this symptom and should be removed. The evaporator may appear and sound normal, but will be at a higher temperature than desired, resulting in longer than expected run times.

Seriously overcharged system
If so much refrigerant exists in the system that it raises the temperature of the evaporator above 32 deg F, the surface will only be sweating and cold to the touch, resembling an undercharged condition. But the copper lines leading back to the compressor, and maybe even the compressor itself, will also be cold and sweating, and there will probably be a sound similar to a mountain stream coming from the evaporator. This is a potentially damaging condition as liquid can reach the compressor where it can damage the valves, since refrigeration compressors are designed to compress gas only.

 
 
 
Respectfully;
Mohammad and Aty
B&B Kokomo
Amel 54 #099
 

From: amelyachtowners@... [mailto:amelyachtowners@...]
Sent: Saturday, March 31, 2018 3:14 PM
To: amelyachtowners@...
Subject: [Amel Yacht Owners] Frigoboat re-charging

 

Hi all,

Would anyone know where I can find an idiots guide to re-charging a friogboat fridge whcih uses R134A refrigerant?

Cheers,
Paul
Ya Fohi - Amel 54 #98
ya_fohi
 

Hi all once again!

I'd like to resume this thread having now acquired a gauge set and a cylinder of R134A. After lots of trawling the web, tI'm still not 100% sure about my diagnosis for my faulty freezer. After running for quite some time, the high pressure reading is 105 psi and the low is minus 10 in Hg. This leads me to believe that there is a blockage in the capilliary tube or the evaporator, as from what I have managed to find out the low pressure should be around 7-10psi. The high pressure tube frosts up to the point of entry to the evaporator but the evaporator remains cold but not frosted. I've tried heating it with a mini blow torch (as I've seen fridge techs do) but to no avail.

I would be interested if someone could confirm my diagnosis or correct it if it is wrong, and offer any further advice on how the remedy the problem. I understand it may require a vacuum in which case I'll have to get the experts in.

Cheres,
Paul
Ya Fohi - Amel 54 #98
John Clark
 

Paul,  you say the HP tube is frosted before entering the evaporator/freezer?  10" vac is too low,  105 psi does sound high....


On Wed, Jun 27, 2018, 6:16 PM sharongbrown@... [amelyachtowners] <amelyachtowners@...> wrote:
 

Hi all once again!

I'd like to resume this thread having now acquired a gauge set and a cylinder of R134A. After lots of trawling the web, tI'm still not 100% sure about my diagnosis for my faulty freezer. After running for quite some time, the high pressure reading is 105 psi and the low is minus 10 in Hg. This leads me to believe that there is a blockage in the capilliary tube or the evaporator, as from what I have managed to find out the low pressure should be around 7-10psi. The high pressure tube frosts up to the point of entry to the evaporator but the evaporator remains cold but not frosted. I've tried heating it with a mini blow torch (as I've seen fridge techs do) but to no avail.

I would be interested if someone could confirm my diagnosis or correct it if it is wrong, and offer any further advice on how the remedy the problem. I understand it may require a vacuum in which case I'll have to get the experts in.

Cheres,
Paul
Ya Fohi - Amel 54 #98
Ian Shepherd
 

Hi Paul,

I have been servicing my fridge/freezers on Crusader for some years now, and also the unit in my flat. From what you say, I would suspect a blockage in the evaporator, most likely caused by ice forming due to moisture getting into the system. I would suggest that you add two items to your kit. A vacuum pump and an infra-red temperature measuring gun.

Experience has shown me that it is generally a waste of time and gas re-gassing without evacuating the system for a minimum of 30 minutes on a low pressure system such as the SM Frigaboat equipment. High pressure systems need maybe 15-25 minutes longer if you have added one to you boat, such as a ice making machine. Vacuum pumps are available at a reasonable cost and well worth having.

I had a symptom similar to yours on my Scholte fridge freezer in my flat recently. After about 20 minutes of evacuating there was a sudden plop and the obstruction came free. Again I suspect it was caused by ice.

When it comes to re-gassing, I have read of many ways, some even measuring the current taken by the compressor. However, this is what I do:

1/ Vacuum pump for 30 minutes. Close the manifold valves and switch off the pump. Monitor the vacuum pressure for about 20 minutes. If it starts to decrease , you have a leak. Then I think you do need an expert to come find it and fix it.

2/ Let your R134a into the system for about 5 seconds only, then switch on the fridge with the thermostat turned fully up. The compressor has an outlet pipe called the liquid line, and a return pipe called the suction line. The connector that you attach your blue hose to is usually close to the compressor on the suction line.

3/ Touch the liquid line with your fingers. It should get hot. If it does not, then add more gas a little at a time till it does.

4/ Once this is happening you have compressed refrigerant on its way to the condenser which removes some heat through the fan, before it travels to the evaporator chest, which doubles as the ice box on the Frigaboat fridge.

5/ Using an infra-red temperature gun, measure the temperature of the evaporator chest. It should be headed downwards so somewhere around -15C on the fridge and -25C in the under the salon seat freezer. Remember it does take time to achieve these temperatures. The temperature around the whole of the evaporator chest should be about the same. If it is not, then you need to add more gas a little at a time and wait before re-measuring. Patience is the key word.

6/ Finally feel the temperature of the suction line close to where it enters the compressor. It should feel no more than cool, with perhaps a wet feel to the pipe. If it ices up, it means too much gas and that liquid is returning to the compressor instead of heat carrying gas.

It does take a lot of patience to get the balance just right. I leave the bottle and manifold connected for a full day before I am satisfied that I have it about right. Usually I end up with a suction line pressure of around 5-6 psi, which corresponds with what I have read, 7 psi being the maximum that an R134a system should run, or so some say.

I hope that this helps Paul. It's a bit of an art to get it right and I have had some professionals make a complete mess of my refrigeration, and others that have done an excellent job. However, when you are 'out there' and it goes wrong, there is no money better spent in having the equipment on board to fix it whist under way.

A quick question. How did you measure the high pressure side of the compressor? Did you fit a line tap? Maybe there is a connector on the liquid line as standard on the 54?

Regards

Ian shepherd SM2K 414 (2003) Crusader

Herzliya Marina Israel


On 28/06/2018 01:16, sharongbrown@... [amelyachtowners] wrote:

 
Hi all once again!

I'd like to resume this thread having now acquired a gauge set and a cylinder of R134A. After lots of trawling the web, tI'm still not 100% sure about my diagnosis for my faulty freezer. After running for quite some time, the high pressure reading is 105 psi and the low is minus 10 in Hg. This leads me to believe that there is a blockage in the capilliary tube or the evaporator, as from what I have managed to find out the low pressure should be around 7-10psi. The high pressure tube frosts up to the point of entry to the evaporator but the evaporator remains cold but not frosted. I've tried heating it with a mini blow torch (as I've seen fridge techs do) but to no avail.

I would be interested if someone could confirm my diagnosis or correct it if it is wrong, and offer any further advice on how the remedy the problem. I understand it may require a vacuum in which case I'll have to get the experts in.

Cheres,
Paul
Ya Fohi - Amel 54 #98
ya_fohi
 

Ian,

Thanks for the detailed info - that's a great help. The 54 has a Frigoboat with connectors for both high & low pressure. It does seem then that I have a blockage then. I'm in Antigua so finding a vacuum pump at reasonable price may be a bit challenging. If I do find one, then what is the procedure to use it? I assume I connect to the service port in the manifold (the centre one), but then which side do I open - high or low?

Cheers,
Paul
Ian Shepherd
 

Hi Paul,

Antigua might prove more expensive but there must be a source to cope with all the a/c units out there. I can't remember what the mains voltage is in Antigua. I suspect 220V due to it's heritage?

I normally connect my gas bottle to the centre port using the yellow hose, the blue compressor suction line to the blue port and the pump to the red port. In this case I would leave the gas bottle closed and open both the blue and red valves. Be sure that the hoses are the right way round. The ends are different, one end designed to open the valve in the end of the compressor connection fitting.

Before you recharge the gas, be certain to purge both the manifold and the blue line. Shut both valves then open the gas bottle then the blue valve with the blue hose fitting slackened where it connects to the compressor. Let the gas flow through then tighten the hose so that the gas flows into the compressor. If you don't purge and any air gets into the system then you will also get moisture in as well, ruining the good work you just did.

Good luck. I will be off line for a couple of days as I am sailing back to Cyprus tomorrow.

Ian Shepherd SM2K 414 Crusader Israel



On 28/06/2018 19:44, sharongbrown@... [amelyachtowners] wrote:

 
Ian,

Thanks for the detailed info - that's a great help. The 54 has a Frigoboat with connectors for both high & low pressure. It does seem then that I have a blockage then. I'm in Antigua so finding a vacuum pump at reasonable price may be a bit challenging. If I do find one, then what is the procedure to use it? I assume I connect to the service port in the manifold (the centre one), but then which side do I open - high or low?

Cheers,
Paul
Craig Briggs
 

Paul,

In addition to Ian's excellent info, you'll want to be sure to install a new dryer each time you open/evacuate the system, especially with your moisture issue. Since Ian didn't mention it, I'm guessing your units may have had Frigoboat's pre-charged freon lines with no drier, but since you're opening the system for evacuation it's critical to install one - very simple and $25.. (I've got Northern Lights refrigeration which doesn't use pre-charged lines, so a drier is standard.)

Cheers, Craig Briggs, SN68 Sangaris, Brunswick, GA


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

Ian,

Thanks for the detailed info - that's a great help. The 54 has a Frigoboat with connectors for both high & low pressure. It does seem then that I have a blockage then. I'm in Antigua so finding a vacuum pump at reasonable price may be a bit challenging. If I do find one, then what is the procedure to use it? I assume I connect to the service port in the manifold (the centre one), but then which side do I open - high or low?

Cheers,
Paul

1 - 13 of 13