Freezer Frosting Up Too Fast

[sailorboy1]

Originally Posted by billknny

Hint to everybody else who has been following this for the entertainment:

if you defrost your fridge and do NOT "get all the ice/water/frost out" it just goes right back onto the evaporator again!

You'd think this would have been obvious.

Yes is is obvious that water/ice/frost will go back on the evaporator, I'm not an idiot and understand that.

BUT IT ISN'T OBVIOUS THAT A SMALL LAYER OF FROST THAT WAS LEFT ON THE EVAPORATOR WILL GROW BY A FACTOR OF 10 IN 24 HOURS

[gonesail]

I turned the temperature all the way down on my little ice box and have had little to no frost on the freezer coils .. but that may not work for you if you need to keep things frozen.

[a64pilot]

Your looking at this all wrong, you don’t have an ice build up problem,
You have a Watermaker

[sailorboy1]

Originally Posted by a64pilot

Your looking at this all wrong, you don’t have an ice build up problem,
You have a Watermaker

And it was basically free

[Richard Kollmann]

No, not a Watermaker its a moist air leaking Dehumidifier that requires frequent defrosting.

[Sailing Drummer]

sailorboy1

If I remember correctly, you had this same thing happen a while back. And it was the same time I was having the exact same problem. Well, I’m having that problem again! And trust me, I’m not trying to copy you!

I have a strong suspicion about my freezer and it may be the same as yours.

A previous owner had the boxes rebuilt. I think the insulation is the problem with mine. I bet it’s totally saturated. Like you, I’ve replaced the seals a few times. My system is a holding plate system but we both suffer the same problem - moisture. Thinking back to when my problems have occurred, it’s always been in high humidity locations. Right now I’m in Lake Worth. Last time I was here the same thing happened.

I’ve done the tests - pull a piece of paper, shine a light - and both passed. It’s not the seals. And there are no openings , everything is plugged. It’s moisture from somewhere. And I think mine and maybe yours, is from the insulation. And for some reason the wet insulation gets a lot wetter when the humidity is high and somehow gets into the freezer.

This last week I’ve had to scrape frost off the plate every day. I take the temp with an IR thermometer. The plate is usually about 0 to +5 F. Then I scrape the frost off and take the temp, it’s -14 F.

I really don’t want to tear up a really nice looking galley, but I can see the writing on the walls.

[sailorboy1]

Could be. The thing is that it's hard to convince myself to tear apart something on a theory. But who knows i may get there with time.

[sailorboy1]

Well took 3 days to ice/frost up enough that the spillover system could not maintain refrigeration side less that 40 degrees F. The day after last defrosting it was able to maintain 35-36 degrees. As soon as half the freezer plates iced up the system could not maintain temps and even the top of the freezer started getting warmer.

This combined with that the system is only using around 4 amps and never seems to cycle has me starting to question the system charge level. So unless someone can talk me out of it i think i am going to give my 19 year old system a small amount of charge.

[Richard Kollmann]

It is not likely that moisture in the insulation has caused box interior frost if door and lid seals are tightly compressed. Four amp current draw may indicate poor performance and frost amounts that you are reporting. Someone earlier in this long thread mentioned what about low on refrigerant.

Knowing brand and model size of compressor along with whether it is a capillary tube refrigerant flow control system or TXV. This information can be used to project correct amount of refrigerant/amperage draw required for that compressors best performance. Example if compressor is a fixed speed Danfoss BD2.5 or BD3 and air cooled 5 amp stabilized amperage will deliver system maximum output. The newer variable compressor amperage efficiency's are based on compressor speed versus compressor running time.

[a64pilot]

Wet or inefficient insulation won’t cause excess frost, unless of course there is a way for the moisture to penetrate the wall and get into the box. It will cause excessive power use, but I can’t see how excess frost, unless the moisture is getting in the box.
Only penetration I know you have for sure is the hole where the tubes go through, perhaps that hole is the source of the moisture? If you know it’s not the drain, and you know it’s not the seals, that doesn’t leave much else left, excepting the food itself of course.
But if your sure it’s not any of those, then it may be the hole where the compressor tubes go through, just by process of elimination.
Being a paranoid person when I ran mine though I used spray foam insulation to plug the hole, then after it cured I painted a couple of coats of 5200 on it from both sides, 5200 takes a long time to set so I did it on successive weekends, helped a lot that I wasn’t living aboard at the time, but I believe two coats of 5200 on both sides to be a pretty waterproof seal.
If you are and have an Engel maybe you can get by with just using it for a few days?

Personally I can’t see how refrigerant charge level could cause excess frost, once the evaporator is below freezing, it’s going to accumulate frost until the relative humidity level drops in the box and you reach stasis. Airs ability to hold water in suspension I believe drops with temperature.
Does it matter if the evaporator is -30 or -10?

[sailorboy1]

It's an Adler-Barbour Cool Machine with a BD50 compressor and mechanical thermostat freezer system.

I defrosted the freezer again last night. After the system pretty quickly dropped the frig side from 45 to 38 in couple of hours.

This morning the spillover fan was cycling between 35-36 as set. There is frost covering all the evaporator, so to my reading that means there is enough refrigerant in the system. Haven't done any work that would have lost refrigerant and if there was a leak I would think it all would have leaked out be now.

It has been the same basic temperature and humidity here the past 3 months so that isn't the problem. But, it of course effects the system.

[Richard Kollmann]

Originally Posted by sailorboy1

It's an Adler-Barbour Cool Machine with a BD50 compressor and mechanical thermostat freezer system.

I defrosted the freezer again last night. After the system pretty quickly dropped the frig side from 45 to 38 in couple of hours.

This morning the spillover fan was cycling between 35-36 as set. There is frost covering all the evaporator, so to my reading that means there is enough refrigerant in the system. Haven't done any work that would have lost refrigerant and if there was a leak I would think it all would have leaked out be now.

It has been the same basic temperature and humidity here the past 3 months so that isn't the problem. But, it of course effects the system.

I have no disagreement with what you are saying but 4 amp normal draw on a BD50 compress tells any technician that your unit is running without a resistor in thermostat circuit keeping compressor at minimum 2,000 Rpm or refrigerant volume is slightly low. Yes even slightly low on refrigerant will display 90% evaporator frost cover. Forgetting excessive frost build up, at 4 amp draw your Adler Barbour at freezer evaporator temperature is inefficient if compressor run cycle is greater than 30 minutes any hour.

I would suggest checking for resistance in thermostat wiring, circuit no resistance will operate compressor at low speed, 1500 ohms resistance is high speed 3,500 Rpm. When Adler Barbour sells an evaporator they include a thermostat with it that includes already installed correct speed resistor to match K value for that size evaporator.

[sailorboy1]

Well i can check resistance, but it has the same thermostat that was installed with 19 years ago.

My AB manual says the compressor is suppose run at 3000 rpms. I don't care about efficiency as power difference is minor.

[Richard Kollmann]

Originally Posted by sailorboy1

Well i can check resistance, but it has the same thermostat that it was installed with 19 years ago.

Then you need to determine if the evaporator is Adler Barbour's smallest evaporator which was the wrong evaporator in the beginning. These units with Power Plates generally run compressor at max speed. Each AB evaporator will have its own BD50 speed recommendation. A perfect marriage of compressor to evaporator some will say compressor only runs 30% or less of the time.

Normal amps for BD50 depending on evaporator size and heat load in box is 4.5 to 6.8 amps. A box with a spillover refrigerator section drawing only 4 amps is hard to believe.

[RickG]

I'll watch this for any resolution. We have an Adler Barber with a BD50 compresor and a spill over refrigerator. In the Caribbean, we defrost ever two weeks in the summer and every three weeks in the winter. I would love to move to dedicated freezer and refrigerator compressors.

Cheers, RickG