Evaporator plate accumulates los of ice regularly

[LifesBetterWhenYoureBeating]

Hi everyone,

Several months ago I had a 12v compressor (bd50) and evaporator plate installed in my ice box to replace my engine driven compressor and holding plate. I've never dealt with a system like this before and the technician (a refrigeration expert who mainly deals with non marine stuff) told me I needed to play with the thermostat to find a temperature that would keep a thin layer of frost on the plate, and that's what I did. As far as I can tell, though, that layer of frost melts and a new one replaces it on a regular basis and I believe that's what causes a lot of ice to accumulate at the bottom half of my plate. I thought this was normal and have been regularly defrosting the plate (with the help of a hot water spray to make it quicker) but a few other cruisers have recently told me their evaporator plate never needs to be defrosted, so I'm wondering if maybe I have mine set to a temp too low? Or maybe the level of refrigerant on my system is not ideal and that's why the thin layer of frost keeps melting?

PS: My box is 5.7ft³ and pretty well insulated, so the compressor is probably oversized and the plate is appropriately sized

Thanks in advance!

[markxengineerin]

Following this thread with interest, as I also get some ice buildup, in my case all over the "holding plate" that I'm effectively using as an evaporator. I attributed the problem to humidity and moisture getting into the fridge (tiny leaks in lid). I re-made the whole lid to a simple 1 piece design that I'm certain does not leak anymore, and the ice has slowed down greatly. I used to defrost every few weeks, now I can go a few months. But I'd like to reduce that to zero. This is only one datapoint, there may be other variables I'm not accounting for, such as how "wet" the food I'm storing is.

On a related question, does the layer of ice affect the efficiency of the system? I don't think it would, it seems like a little extra conduction through the ice would be minimal influence, but curious if anyone knows.

[Bill O]

Originally Posted by LifesBetterWhenYoureBeating

Hi everyone,

Several months ago I had a 12v compressor (bd50) and evaporator plate installed in my ice box to replace my engine driven compressor and holding plate. I've never dealt with a system like this before and the technician (a refrigeration expert who mainly deals with non marine stuff) told me I needed to play with the thermostat to find a temperature that would keep a thin layer of frost on the plate, and that's what I did. As far as I can tell, though, that layer of frost melts and a new one replaces it on a regular basis and I believe that's what causes a lot of ice to accumulate at the bottom half of my plate. I thought this was normal and have been regularly defrosting the plate (with the help of a hot water spray to make it quicker) but a few other cruisers have recently told me their evaporator plate never needs to be defrosted, so I'm wondering if maybe I have mine set to a temp too low? Or maybe the level of refrigerant on my system is not ideal and that's why the thin layer of frost keeps melting?

PS: My box is 5.7ft³ and pretty well insulated, so the compressor is probably oversized and the plate is appropriately sized

Thanks in advance!

Need more info. What temp are you attempting to hold the box? Is it a straight fridge or spill over? Is you box a top load or front load? What system are you using? Are you using a speed controller or one set rpm?

The plate should freeze as the refrigerant comes in and frost over the whole plate. Is your exit tube from the evap plate frozen? If it has more than a slight frost (it will since it is near the very cold incoming line), check the line going outside of the box. Is it frozen? If so, the system may be over filled.

[sailorboy1]

Ice build up means moisture is getting into the box. Ice melting and then refreezing means there is a temperature control issue.

[boatpoker]

The more you open the door, the more ice you will get. I would not believe anyone who says they never get ice on their evaporator plate. We defrost about every 2 months and live aboard full time.

[markxengineerin]

How about automatic defrost, do any boats have them/ would it be retrofit-able?
https://www.appliance-parts-experts....9_p_11507.html
I'm not sure this is a good idea, as a lot of our systems (mine) have a barely adequate compressor that takes a full day to cool down. Maybe this more frequent defrost is better for applications with lots of excess heating/cooling power available? I would like to skip the need for manual defrost if there's a way.

[LifesBetterWhenYoureBeating]

Originally Posted by Bill O

Need more info. What temp are you attempting to hold the box? Is it a straight fridge or spill over? Is you box a top load or front load? What system are you using? Are you using a speed controller or one set rpm?

The plate should freeze as the refrigerant comes in and frost over the whole plate. Is your exit tube from the evap plate frozen? If it has more than a slight frost (it will since it is near the very cold incoming line), check the line going outside of the box. Is it frozen? If so, the system may be over filled.

It's a straight fridge. Both top and front load, but mainly use the top and certainly not often. Fridge is always kept pretty full. It's and old bd50 compressor/controller so I believe it has no speed control?

The thermostat has been between 0 and - 5° (C). If I go lower than that the return line freezes, and higher I don't get Frost on the plate.

[SailingHarmonie]

Ice is water. If you are accumulating Ice inside your box you are getting water inside. There are a couple common sources for air inside the box.

1.) A badly sealed box. (Very common)
2.) A frequently opened box.
3.) Poorly sealed food.

If you open you lid, and spend a minute or two getting your dinner out, the cold bottom of the lid can accumulate quite a bit of condensation. Wipe this off before closing the lid.

The contribution of food is frequently missed. Water evaporates from food that is not tightly packaged (even when frozen), and moves to the evaporator plate. People frequently have open containers of icecubes that greatly contribute to frost on the plate.

Eliminate those source of water, and you will greatly slow frost accumulation.

[s/v Jedi]

Unless you are opening the box all the time, the problem is the seals in the lids and/or doors. You need to replace them.

Like others wrote, the plate should have frost all over it, and the refrigerant return line should just have a couple inches of frost as well. But you do not control this with the thermostat (which is for setting the box temperature) but with the amount of refrigerant in the system.

I would recommend to find another tech.

[FlyingScot]

Every time you open the box, a lot of moist air enters as well.

Door seals are critical as the pressure drops when the box cools off effectively trying to suck warm moist air into the box.

Living in the tropics means humidity and ice/water in your fridge on a regular basis.

If just as a fridge, then the sweet spot for us is one that allows the box to stay cold but the plates heat up enough to melt the ice between cycles. This means water at the bottom vs. thick ice on the evaporator plate.

[GreenWave]

Originally Posted by markxengineerin

How about automatic defrost, do any boats have them/ would it be retrofit-able?
https://www.appliance-parts-experts....9_p_11507.html
I'm not sure this is a good idea, as a lot of our systems (mine) have a barely adequate compressor that takes a full day to cool down. Maybe this more frequent defrost is better for applications with lots of excess heating/cooling power available? I would like to skip the need for manual defrost if there's a way.

Automatic defrost is the worse thing for ANY freezer - domestic or marine. Aside from a power waste it is not optimal for food preservation.

[markxengineerin]

Power waste isn't really a concern for boats with excess solar. I'm throwing power away after ~11AM each day, would happily use it for automatic defrost if there was a kit to add it. If using enough (and well-directed) power, I imagine the food won't see much difference, otherwise don't think it would be used on just about all house systems. I haven't heard of it on a boat yet.

[LifesBetterWhenYoureBeating]

Turns out the seals on the front door are in bad shape and fail the dollar test bill. Would something like https://www.amazon.com/Weather-Strip.../dp/B07WTYXDCY be a good option for new seals?

Edit: based on the Amazon reviews it probably isn't as many people report issues with the adhesive tape. Any other suggestions?

[Bill O]

Do you have the ability to use a magnetic gasket (need a steel surface on the other side)?
We had a custom one made here in the US to fit our freezer lid and it's a great seal. Not certain what you have near you?

[LifesBetterWhenYoureBeating]

Originally Posted by Bill O

Do you have the ability to use a magnetic gasket (need a steel surface on the other side)?
We had a custom one made here in the US to fit our freezer lid and it's a great seal. Not certain what you have near you?

Unfortunately that's not an option for me. I've got wood on one side and fiberglass on the other.

Also not many options around here so would rather order online.

The top door is quite heavy and the front one uses a latch that pushes it hard against the frame so I think even strips of foam tape on both sides may be enough, but I might be wrong