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Old 13-03-2019, 00:00   #1
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Sweating pipe

We just had to have a new evaporatior plate made up for our fridge as we couldn't get one locally.
Unlike the old plate which had the cap pipe inside the return pipe ,
it now has two separate copper pipe .
The fridge seen to be working ok but return pipe seen to be sweating quite a lot and water droplets .

Any suggestion what would cause this .
Also I should mention the return pipe as a plastic cover over it like a plastic hose , this was put on so when the copper pipe when fed around the fridge it wouldn't kink .
Would this be the cause of the problem ?
We be grateful for any help you could give as the floor is getting wet with the water drops .

The compressor is a danfoss 35 common in most boats
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Old 13-03-2019, 03:10   #2
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Re: Sweating pipe

Humid air is coming into contact with cold metal. Install Armacell/Armaflex (type) pipe insulation.
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Old 13-03-2019, 07:58   #3
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Re: Sweating pipe

We had a similar problem after having a new/replacement FrigoBoat unit installed. In our case it proved to be that the system was slightly overcharged. Our refer technician removed a small amount of the coolant and then added a foam sleeve around the tubing for good measure, all of which resolved the problem. For further information, however, you might PM Richard Kollman (Sp?), the refrigeration "guru" hereabouts.

FWIW...
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Old 13-03-2019, 10:06   #4
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Re: Sweating pipe

Sweating back used to be a way of determining charge back when the old refrigerants were used.
Some compressors also benefit from cold refrigerant gasses in the return line, they get significant cooling from that.

I don’t think I would myself insulate the line, it’s possible that you could get some liquid back that way, unlikely maybe, but possible.
If it’s working good, I’d leave it alone, sweating and condensation on the return line isn’t something I’d worry about, if it’s otherwise working well.

Of course I’m not familiar with your particular installation.
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Old 13-03-2019, 10:50   #5
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Re: Sweating pipe

Quote:
Originally Posted by medsailor1 View Post
We just had to have a new evaporatior plate made up for our fridge as we couldn't get one locally.
Unlike the old plate which had the cap pipe inside the return pipe ,
it now has two separate copper pipe .
The fridge seen to be working ok but return pipe seen to be sweating quite a lot and water droplets .

Any suggestion what would cause this .
Also I should mention the return pipe as a plastic cover over it like a plastic hose , this was put on so when the copper pipe when fed around the fridge it wouldn't kink .
Would this be the cause of the problem ?
We be grateful for any help you could give as the floor is getting wet with the water drops .

The compressor is a danfoss 35 common in most boats

It is difficult to answer questions when a refrigeration system is modified from the original design. Other than condensation on return line are you satisfied with the performance as is? if moisture dripping could be eliminated?

Does cap tube wrap around return line if so how many times?

If we need the two line contacting each other could this be done without disturbing anything ?

Describe new evaporator or send picture. Is the complete surface of evaporator covered with frost?

Is the condensation or frost extending all the way to compressor?

Approximately how long is the return line?

What is diameter of new capillary tube and its length?

What is amperage draw of compressor with new evaporator?
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Old 13-03-2019, 14:28   #6
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Sweating pipe

Quote:
Originally Posted by Richard Kollmann View Post
It is difficult to answer questions when a refrigeration system is modified from the original design. Other than condensation on return line are you satisfied with the performance as is? if moisture dripping could be eliminated?



Does cap tube wrap around return line if so how many times?



If we need the two line contacting each other could this be done without disturbing anything ?



Describe new evaporator or send picture. Is the complete surface of evaporator covered with frost?



Is the condensation or frost extending all the way to compressor?



Approximately how long is the return line?



What is diameter of new capillary tube and its length?



What is amperage draw of compressor with new evaporator?


The cap pipe don't wipe around each other , as I said the new plate as two pipe coming from it .
The plat e it self is the same shape and size as the old plate .
The pipe are about 2 mts long and there no frost but the condensation goes all the way back to the compressor,
There a couple of small paddles or water about 6 ins from where the pipe entered the compressor.
The dim of the cap pipe is the same size as the old pipe .
The complete surface of the evaporator feel as if it's covered by frost .
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Old 13-03-2019, 16:27   #7
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Re: Sweating pipe

The cap pipe don't wipe around each other , as I said the new plate as two pipe coming from it .
Yes. there are two pipes I now assume the capillary tube is not wrapped around the other tube.

The plate it self is the same shape and size as the old plate .
Good.
The pipe are about 2 mts long and there no frost but the condensation goes all the way back to the compressor,
Good.
There a couple of small paddles or water about 6 ins from where the pipe entered the compressor.
No frost anywhere on tubing?

The dim of the cap pipe is the same size as the old pipe
Good.
The complete surface of the evaporator feel as if it's covered by frost .
Feels like is not good enough. Just before compressor is stopped by thermostat is there frost on line coming out of new evaporator If so how far down the line does frost extend towards compressor?

I still need the actually amperage and frost on return line just before compressor stops to confirm what I now believe is low on refrigerant do to incorrect super heat evaporation inside evaporator.
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Old 13-03-2019, 21:42   #8
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Re: Sweating pipe

Quote:
Originally Posted by Richard Kollmann View Post
The cap pipe don't wipe around each other , as I said the new plate as two pipe coming from it .

Yes. there are two pipes I now assume the capillary tube is not wrapped around the other tube.



The plate it self is the same shape and size as the old plate .

Good.

The pipe are about 2 mts long and there no frost but the condensation goes all the way back to the compressor,

Good.

There a couple of small paddles or water about 6 ins from where the pipe entered the compressor.

No frost anywhere on tubing?



The dim of the cap pipe is the same size as the old pipe

Good.

The complete surface of the evaporator feel as if it's covered by frost .

Feels like is not good enough. Just before compressor is stopped by thermostat is there frost on line coming out of new evaporator If so how far down the line does frost extend towards compressor?



I still need the actually amperage and frost on return line just before compressor stops to confirm what I now believe is low on refrigerant do to incorrect super heat evaporation inside evaporator.


Hi Richard
Thanks for your help .
Answer to your question , .
Yes there is frost all over the evaporator plate , I had another look this morning .
There a few mm of frost if any as the pipe leave the the top of the place , the rest of the pipe is clear .
I should mention we inserted the return pipe inside a small plastic pipe most of the way so has we fed it behind the fridge it wouldn't kink .
so there only about 30 cm of pipe showing down by the compressor where the problem is .
Amps is 5 A , manual says at current Absorption 12vdc 6A
You may be able to see the water droplet in the photo .

Click image for larger version

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Old 14-03-2019, 02:04   #9
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Re: Sweating pipe

I do not believe you answered my very first question as to whether you are satisfied with cooling in the box performance now?

If you are positive this unit is now drawing 5 amps I do not see where adding refrigerant will create less liquid refrigerant in return line. The picture shows that this unit has a static air cooled condenser without a fan as there are no wires connected to module fan terminals.

What is size of box inside as a BD35 compressor at 6 amps would be running at max Rpm and in very warm weather.

Now what we know is there is either a condenser cooling problem or a refrigerant flow problem. Many new cabinet refrigerators have condenser between insulation and outer surface which means air space is required around the cabinet. What we do not know is it any of the new solder joints made when installing new evaporator are restricting refrigerant flow.

The only recommendation I would have now is if you can live with the less than efficient operation of this unit the 5 amp current draw will probably not damage the unit.
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Old 14-03-2019, 03:33   #10
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Re: Sweating pipe

Quote:
Originally Posted by Richard Kollmann View Post
I do not believe you answered my very first question as to whether you are satisfied with cooling in the box performance now?



If you are positive this unit is now drawing 5 amps I do not see where adding refrigerant will create less liquid refrigerant in return line. The picture shows that this unit has a static air cooled condenser without a fan as there are no wires connected to module fan terminals.



What is size of box inside as a BD35 compressor at 6 amps would be running at max Rpm and in very warm weather.



Now what we know is there is either a condenser cooling problem or a refrigerant flow problem. Many new cabinet refrigerators have condenser between insulation and outer surface which means air space is required around the cabinet. What we do not know is it any of the new solder joints made when installing new evaporator are restricting refrigerant flow.



The only recommendation I would have now is if you can live with the less than efficient operation of this unit the 5 amp current draw will probably not damage the unit.


The fridge is keel cooled so no fan .
Size of box 60x60x40 cm
The new plate is the same size as the old plate .
Temp in fridge is 5.4c half way down with stat set at five , although that don't mean much
And there about 1c to 1.5c different in temp between the cap pipe and the return pipe if that's any help .( 15.4 16.6 reading taken after the keel cooler on cap pipe and just before the connection by the compressor on return pipe )
As far as the fridge cooling performance and if I am satisfied, it's work .
One concern is I read too much gas can mess the compressor, another concern is it not good to have water dripping inside the Boat .
Also I been told before posting here by isotherm that the problem too much gas but I do to want to start letting out gas if that's not the case .
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Old 14-03-2019, 05:34   #11
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Re: Sweating pipe

I should have ask in the beginning the manufacture of system this always makes a difference when troubleshooting a problem. Why was the evaporator replaced?

If I new what speed the compressor was set to run at now that the amperage is confirmed at 5 amps I could judge refrigerant volume. Isotherm advice would be correct if there was frost on line coming out of evaporator extending towards compressor. It is also possible that 5 amps is caused by a flow restriction and too much refrigerant.

Frigoboat keel cooler systems do experience refrigerant flow problems do to their filter dryer 's location. They recommend when replacing evaporator cap tube assembly to instal an additional filter ahead of the cap tube, was a new filter installed to protect new cap tube opening?
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Old 14-03-2019, 06:59   #12
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Sweating pipe

This is a new unit , but as we tried to fed the pipe through the the hole and around the back of the fridge box , well I think you can guess what I going to say

Anyway we in Tunisia at the moment and no way can we get our hand on another one and the guy here said he couldn't fix the break so said he make us a new plate , look like a good job but we have this problem . Unlike old fridge there only one speed the old one had three speeds . Yeah of knowing what speed it is ?
So are you saying there too much gas or you think there a restriction some where ? Is it worth letting out a bit of gas ?
We tried to get the guy back but we have more chance or being able to sail all summer long without the use of the engine

Got hands on clamp Amp meter and it read 4.1A

Not sure if this should happen or not but the compressor seen to start slow for a few second before it runs at speed
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Old 14-03-2019, 07:14   #13
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Sweating pipe

Does this help , I found in the Manuel, min rotation speed 1850rpm
Also found this see photo , mine is a black compressor so look like 3000 rpm Click image for larger version

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Old 14-03-2019, 08:29   #14
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Re: Sweating pipe

Do NOT let out refrigerant.

The only way to find out what speed compressor is running at is to disconnect thermostat wires C and T from module and with an ohm meter check resistance from one lose wire through thermostat to the other wire. Zero resistance would run compressor at 2,000 rpm and 1500 ohms 3,500 rpm. See picture top left for ohms verses speeds. The 1850 figure is a start control speed is of no value if compressor runs.

Is it possible for you to add a small amount of refrigerant to increase amperage from 4.1 amps to 5.5 amps? The compressor must be turned off first then purge air from the servicing equipment and hose before connecting it to compressor.
Start compressor and add correct refrigerant very slowly as it will take only one to two ounces to reach a steady pressure for at least five minutes holding amperage of 5.5 amps. If it goes over 5.5 amps a little it can be corrected later after a good performance test run.
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Old 14-03-2019, 10:09   #15
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Re: Sweating pipe

Thanks Richard. I have a go putting putting more gas in as I can buy it here .
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