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Old 12-04-2013, 11:33   #1
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Fridge high current draw

Hi,

I have a frigoboat elec condenser fridge which has been reliable and efficient, normally drawing 5-5.5 amp when on and on for less than 50% of the time.

I had a problem about 2 months ago and lost all coolant, a faulty joint was traced and resoldered and the system refilled.
Since this work the fridge now draws 7-8amps and is killing our batteries, it is however good and cold now.

I discovered some issues with the wiring, the cable had corroded causing high resistance, and replaced both the supply and thermostat cables.

The fridge still draws 8 amps, any ideas why ????

thanks in advance

Mark
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Old 12-04-2013, 11:52   #2
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Re: Fridge high current draw

is it possible the system got air /moisture in it when you lost the refrigerant? You might need a total evacuation and recharge. Also, does it have the little drier can in the system? if so, it may have become saturated with moisture... of course.. i really know squat about refrigeration.....
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Old 12-04-2013, 11:56   #3
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Re: Fridge high current draw

I 2nd the "total evacuation and recharge"
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Old 12-04-2013, 12:06   #4
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The proper term is having non-condensables in the system. By not evacuating all the air out of a system it results in excessive head/high side pressure which causes higher amp draw. It will also cause higher discharge temp and shortened compressor life.

The best thing to do if find a tech that will perform a triple evacuation. This is where the system is evacuated then filled with dry pure nitrogen. The system is then evacuated and once again filled with nitrogen. Then the system is evacuated one last time and then charged with refrigerant.

This triple evacuation uses the nitrogen to remove the moisture stuck in the system just like when they flow nitrogen through the telephone lines to dry them out

But find a tech that will triple evacuate the system then charge the refrigerant by weight. The last part is very important. If a tech is just eye balling the gauges he will either under or over fill the system with most times being over filled.
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Old 12-04-2013, 13:49   #5
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Re: Fridge high current draw

Seabuffalo's advice is spot on. Also be aware that after restarting it, the smart controller on the Frigoboat system starts off at high compesser rpm and 6-8 amp current draw. After a day it learns how fast to run the compressor to result in a 30-50% on duty cycle and typically the current drops to 3-4 amps.

David
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Old 12-04-2013, 13:58   #6
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Re: Fridge high current draw

The Frigoboat units should not be filled by gauges, weight of R143a or any rule of thumb methods. The correct procedure is clearly explained in the documentation.(basically, with compressor turned off, fill through both service valves until equalized, then close high side valve, start compressor and fill through low side valve in bursts with a little run-time in between, until you see frost going from the evaporator plate onto the copper refrigerator line. I fill until I just see the frost appear on the line where it exits the box.
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Old 12-04-2013, 15:05   #7
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Jedi I bet if you email frigoboat and ask them what the charge weight is they will tell you. The reason they don't specify it and instead use the frost on the line method is so they can sell to the DIY people. The other reason is people will see XXX oz or lbs and try to put in 1/2 or 3/4 a can by the weight on the label estimating in their hand how much is used.

The proper way to charge a capillary tube system is by weight and for a expansion valve system weight or superheat and subcooling.

Back in the days of R-12 and R-22 systems with mineral oil were more DIY tolerant. But now with POE oil that absorbs moisture out of the air quickly and blended refrigerants like R-410 or R-404a that can fractionate, the results of DIY attempts can be costly.
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Old 12-04-2013, 15:19   #8
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Re: Fridge high current draw

Rather than speculate the fact is you know refrigerant was tampered with so take a less expensive non destructive approach yourself to define and correct problem. By examining frost pattern of evaporator and refrigerant return line frost you can determine it refrigerant is contaminated with air or there is just too much refrigerant in this capillary tube system. Correct refrigerant and volume on this system will produce normal amperage as recorded in the past (5 amps). Evaporator will have at least a thin coating frost covering over 100% of its surface area and no frost on refrigerant return line outside refrigerator box.

Air in refrigerant or leak test gas will cause only a portion of evaporator to have frost cover and at the same time there will be frost on return line towards compressor.

Too much refrigerant will produce frost area covering 100% of evaporator and also frost on return line to compressor.

I suggest you read through the section TOO MUCH REFRIGERANT by going to my web site at http://www.kollmann-marine.com. and reading through the list on correcting your problem. Most service technicians are experienced enough to keep contaminates out of refrigerant but few know correct refrigerant charge on a system where one ounce of refrigerant can unbalance this small system.
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Old 12-04-2013, 15:22   #9
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Re: Fridge high current draw

Quote:
Originally Posted by SeaBuffalo View Post
Jedi I bet if you email frigoboat and ask them what the charge weight is they will tell you. The reason they don't specify it and instead use the frost on the line method is so they can sell to the DIY people. The other reason is people will see XXX oz or lbs and try to put in 1/2 or 3/4 a can by the weight on the label estimating in their hand how much is used.

The proper way to charge a capillary tube system is by weight and for a expansion valve system weight or superheat and subcooling.

Back in the days of R-12 and R-22 systems with mineral oil were more DIY tolerant. But now with POE oil that absorbs moisture out of the air quickly and blended refrigerants like R-410 or R-404a that can fractionate, the results of DIY attempts can be costly.
You would need to know exactly which evaporator plate is used, keelcooler and which refrigerant extensions etc. because they all determine volume and weight needed. Also important: the climate in which you use the unit makes a difference. When we use the A/C aboard, the temperature drops enough to put frost on the return lines.

But I guess you know better than the manufacturer
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Old 12-04-2013, 18:13   #10
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Quote:
Originally Posted by s/v Jedi View Post

But I guess you know better than the manufacturer
The end of your response was totally uncalled for.

My point was that most manufactures will specify how much charge each component will require and you can make a list to figure the charge needed.

As far as the climate / condensing medium air or water that's irrelevant when using a calculated charge. With such a small system with a capillary tube it's recommended that if a low charge is suspected to just evacuate and charge with a weigh in.

Frigoboat's instructions are NOT the industry norm. There is a lot of room for error with just looking for frost on a line because of too many variables.

As someone who was professionally schooled with fifteen years in refrigeration I can tell you that a manufacture not specifying charge weight or offering a charging chart is not industry standard.

What they are offering in their manual is a way to charge a system that appeals to DIY people with minimal experience or tools but at the risk of flooding the compressor or starving it with high superheat.
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Old 12-04-2013, 20:45   #11
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Re: Fridge high current draw

Sorry Buffalo, but we're not discussing industry norms, we're discussing Frigoboat systems. If you want them (Frigoboat) to adhere to industry norms you need to contact them, not put that to me because I can't help you with it.

I have seen the pro's evacuate and charge Frigoboat systems and I'm sorry to say it was a horror show. Almost a crime to charge money for it. That was what triggered me to buy the books and study this, then design my own system and build and service it. When I tested my box with block ice it was within 7% of my calculated insulation performance. The techs I have seen work on boats (incl. south Florida) can't even tell a R-value of any insulating material. They roll their eyes when you ask to run their pump a bit longer when they want to switch it off after 3 minutes.

Richard Kollman also posted about looking at the frost on the evaporator and lines as an indicator of correct charge. He is an industry professional, so the Frigoboat instructions are not so weird.

Quote:
Originally Posted by SeaBuffalo View Post
The end of your response was totally uncalled for.

My point was that most manufactures will specify how much charge each component will require and you can make a list to figure the charge needed.

As far as the climate / condensing medium air or water that's irrelevant when using a calculated charge. With such a small system with a capillary tube it's recommended that if a low charge is suspected to just evacuate and charge with a weigh in.

Frigoboat's instructions are NOT the industry norm. There is a lot of room for error with just looking for frost on a line because of too many variables.

As someone who was professionally schooled with fifteen years in refrigeration I can tell you that a manufacture not specifying charge weight or offering a charging chart is not industry standard.

What they are offering in their manual is a way to charge a system that appeals to DIY people with minimal experience or tools but at the risk of flooding the compressor or starving it with high superheat.
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Old 12-04-2013, 22:33   #12
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Quote:
Originally Posted by "s/v Jedi
That was what triggered me to buy the books and study this, then design my own system and build and service it.
So as you told me, now you know better than the manufacturer?

My final thoughts are that putting a capillary tube on a system that is designed to be field installed and wide ranging condensing temps is nothing more than cutting corners. A system with a TXV would have higher efficiency and would be easier to charge.

And yes there are plenty of hacks in every field. I've see guys run vacuum pumps five minutes and call it a day. If they are not pulling to 500 microns they are wasting time.

But I still standby my statement that there is no reason that Frigoboat cannot publish a initial weight of charging charge. As Mr Krollman said a ounce one way or the other can be critical.
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Old 13-04-2013, 05:56   #13
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[QUOTE="SeaBuffalo;1209449"]
Quote:
Originally Posted by "s/v Jedi
That was what triggered me to buy the books and study this, then design my own system and build and service it.
So as you told me, now you know better than the manufacturer?

/QUOTE]

For box specifications I found that the Frigoboat recommendations are correct but vague. For charging the system they are correct, it brings you to a perfect charge. Charging a system by weight is a shortcut.
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Old 13-04-2013, 09:04   #14
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Re: Fridge high current draw

Hi Richard

thanks for your response, I have had a look at your website but I am still having problems analysing my problem.

My evaporator is a flat plate bent in the shape of a letter P laying on its side, the bottom part of the evaporator within the P has an even layer of ice, the top of evaporator (on the outside of the P) is very cold but not iced, there is no frosting on the pipe.

The fridge is working pretty hard to maintain the current temp (I turned the thermostat up to check the icing pattern) and is still drawing 7amps.

Am I correct in assuming that no frost on the pipe means the system is NOT overfilled?

Should the top of the "flat P" evaporator be more frosted or is this showing I have contaminates in the system??

Thanks again for your help

Mark
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Old 13-04-2013, 10:10   #15
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Re: Fridge high current draw

Your report did not indicate how long system was running during this test. Evaporator's position is difficult to understand so. If system was running more than 8 hours and still drawing 7 amps and any portion of evaporator larger than 5% of its surface has no frost refrigerant condition and refrigerant flow is in question.

You are correct no frost on line leaving refrigerated area indicates refrigerant is not overcharged.

Seven amps is still too much so air in refrigerant system or poor condenser cooling or refrigerant flow is in question.

Exactly where in system was the line re-soldered? Feel line on each side of repair and report temperature. Also look for the point where frost starts we know frost ends where cold condensation on evaporator starts.
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