Freezer Frosting Up Too Fast

[Richard Kollmann]

Originally Posted by sailorboy1

I have a “logger”, it is called a battery monitor. When going to bed i log the -AH. When i get back up i check it, subtract what it was, divide by the hours since. It is math, but not rocket science.

Not hard to compare the average used about what what the BM says the system is using right now.

Math suggests that last night it may have cycled and “only” ran 94% of the time.

The software that comes with data loggers allows minute to minute graphic display of temperature and compressor start up and stop time. If you are correct compressor rans 94% of the time the first day with a spillover system that could be normal. If a day or two later when box temperatures are stabilized cycling is greater than 50% I would want to know why. The three possibilities causing excessive compressor run time are lack of refrigerant flow, Compressor speed set too low, or poor total box insulation R value.

Lack of refrigerant on your Adler Barbour with that large aluminum evaporator can be checked visually after a few days of operation. To little refrigerant is indicated by insufficient evaporator frost surface cover. Too much refrigerant is indicated by frost on evaporator return line extending more than a few inches down return line.

Correct compressor speed can be achieved by recording amp-hr consumed in 24 hours now and again after increasing compressor speed to the next Danfoss recommended speed. For optimum energy usage under various climate changes you should make up a set of speed resistors as displayed on my web site Slide Show. If you are unable to open it Email me and I will send PDF file.

As to checking quality of insulation this can be done after refrigeration has stabilize box temperature for several days by comparing exterior cabin temperature several inches away against exterior of box insulation temperature in several places. The difference (delta) in temperature from insulation exterior surface and cabin air temp will define insulation quality. Very good insulation a temperature difference no greater than 4 degrees F. Seven degree greater is except able but increases daily energy consumption.
When delta T reaches 10 degrees condensation begins to form on exterior of refrigerated box.
Most people trying to sell refrigeration will tell you that new insulation is a requirement when you buy their units. I take a different approach when insulation is marginal I recommend refrigeration system capable of doing the work needed and boat's electrical power grid upgrades.

[bobty]

Originally Posted by bobty

I had an identical problem with fridge -freezer combination and only solved it when an Aussie marine refrigeration maker was contacted. They sent me their 'Problem resolution data' for this.
You have confirmed seals are good, your problem is that the system is LOW on refrigerant. This causes the cold plate to be extremely cold in parts attracting abnormal and rapid ice deposits. Top up the gas and the problem goes away.
I also fitted a 'heat transfer duct' and now only defrost after mant weeks. The duct is a shallow stainless steel cover located on the freezer side wall over the two fridge air ducts. This prevents fridge air mixing with freezer air while being cooled.

Hi Sailorboy,
As per my PM I contacted my fridgie for a better explanation. He emailed this so hope it helps to explain:

Bob,
I looked at that site and his problem is the same as yours was. You got it right..He needs to add some gas to lift the operating suction pressure to at least above zero PSIG to confirm, then have the leak located (it will be on the low side) and repaired, change dryer, evacuate and regas.
His system ran fine for many years now this. His says his seals are good so rule that out and if there is no abnormal air entry then there is no other cause except short of gas.. period!
Other signs that this system is short include: Low compressor power consumption due to running on low suction PSIG, long run cycles due to only partial proper freezing of the evaporator.
Note also that when a system leaks gas from the low side, the leakage stops /nearly stops as the pressure lowers to or below atmosphere. (Zero PSI)
When a system is short of gas it runs for much longer than usual and with the evaporator (Parts of) at abnormally low temperatures. Normally with a full gas charge the cold plate would all be absorbing heat (refrigerating properly and quickly) with the difference between the plate and air at let’s say 10F With gas lost, a lesser amount of evap is refrigerated (although may show frost) but to extremely low temps. ie: half the evap is now causing that difference to be say 30F. Moisture extracted from air is greatly increased as the temp difference between air and evaporator increases.
He has gone from say a full +10F evaporator extracting heat all over, to a portion of the evap trying to do the job at say -15F or lower. With a full charged system the temperature difference between air and evap attracts a small amount of moisture and also runs for far less time. This is normal. With a partly charged system the temperature difference between air and evap is huge and attracts a much more moisture and also runs near full time and at low compressor consumption. This is NOT normal.

[Richard Kollmann]

bobty, I am concerned your friend may not be giving good advice to Sailorboy1 when he assumes adding refrigerant is a good idea, without confirming first that system needs refrigerant by non destructive test means. Any time servicing equipment is connected to these small systems future reliability is at risk.

Unless your fridgie has detailed information on this spillover box's shape or design the rest of his advice is some what confusing.

[sailorboy1]

I have decided I'm NOT going to add any refrigerant to the system. The evaporator is frosting up fully and the system is maintaining 12-15 degree air temp in top of freezer. I do feel it probably could use a very little amount, but it is so little than I feel the potential downside outweighs the potential upside. Currently the only upside would appear to be a small amount of electrical savings of maybe 5-10AH/day, but that is MAYBE.

The problem that started this was rapid frosting of the evaporator that seemed to indicate seal leaks. But the seals seemed to fully make contact and I had replaced them a couple of times to fix the issue. Turns out that the apparent problem was similar to the seals leak indication as it was the screws into the lid that held the lift arm bracket and the latches (8 screws total). I took those out and caulked the holes and reinstalled and it has now been 8 days. I have had this system a looooong time and with 2 people living full time on the boat a normal defrost time was about a week and it is now back to that.

About 4 months ago I thought I had fixed it with a seal change. But I now think it had just gotten better because I was in a slip with the AC running so the air had less moisture..

So took a year, but finally someone wrote something (wasn't about the screws but enough to get me reset my mind) that rang my bell enough that I gave those screws attention. Sorry I don't remember who and it may have been a different thread, so thanks to whoever it was.

[RickG]

We just defrosted after 21 days. It is winter in the Caribbean and we have been seeing a high of 82F. We had solid ice behind the evaporator. For us, the main source of moisture appears to be the refrigerator spill over.

We need a bit more refrigerator room and it gets jammed with leftovers and drinks. I just ordered the smallest Engel electric 12V fridge/freezer. I'll mount it under our chart table. The hope is that we'll see less frosting with fewer refrigerator door openings.

If we still have a problem with defrosting I think I'll replace the refrigerator with a built in unit that has a dedicated compressor. I'm thinking about cutting out some kitchen counter to add a taller refrigerator that can fill the extra 12" up to the cockpit floor. I really should put a digital controller on the existing compressor.

Cheers, RickG

[ayates]

Originally Posted by Richard Kollmann

Can you provide us with the source of the $25 data logger you mention?

More thatn $25, but I use these for temperature logging: https://www.madgetech.com/products/temp101a/


Allan.

[sailorboy1]

Just fully defrosted today after 11 days. Have cleaned the loose frost of the evaporator, but didn't take the ice off. This morning frig side was warm and that evaporator ice was harder than normal.probably a very small part not frosting up, so a little r134 is probably called for.

But i can live with 11 days defrosting as i have lots of time available.

Overall i know the problem is the spillover arrangement. But currently it isn’t a $1500 problem to fix.

[a64pilot]

Before and after, 26 day interval for comparison, my seals are old and need replacing, they are just cheap Lowe’s door seals or something.

[a64pilot]

Someone had said that they posted a link to magnetic seals, I looked through the thread and didn’t see it, would they repost the link please?

[sailorboy1]

Originally Posted by a64pilot

Someone had said that they posted a link to magnetic seals, I looked through the thread and didn’t see it, would they repost the link please?

Its on different thread about seals, search on my user name

[Coolerking]

Originally Posted by a64pilot

Before and after, 26 day interval for comparison, my seals are old and need replacing, they are just cheap Lowe’s door seals or something.

We do the seam welding on those plates.

[Richard Kollmann]

Originally Posted by Coolerking

We do the seam welding on those plates.

Electric seam welding is the standard for today's eutectic plate tanks as Tig welding adds carbon to stainless weld areas eventually causing pin hole leaks.
That Technautcs plate in picture is seam welded.

[Coolerking]

Originally Posted by Richard Kollmann

Electric seam welding is the standard for today's eutectic plate tanks as Tig welding adds carbon to stainless weld areas eventually causing pin hole leaks.
That Technautcs plate in picture is seam welded.

That's correct, we do the back plates and the seam welding on those, and in fact I looked at a stack of more than 20 more of the same ones we just received the other day, we have been doing this for technautics for many years .

[LarryS1]

I have a similar system and had the same problem. Turns out it isn’t the freezer seal, it’s the refrigerator seal since the two are interconnected. Put a dollar bill between the refrigerator door and the seal. If you can move the dollar bill around, replace the refrigerator seal.

[sailorboy1]

Originally Posted by sailorboy1

I am tired of always having to defrost my freezer. It used to be 7-10 days, but now it is getting tp every 2-3 days (and it hasn’t been hot or humid).

You of course think “seals”. But i have replaced the seals now like 3 times trying different types and feel they are sealing. Yet the system keeps acting like there is an air leak and moisture getting in.

Could it be something else?

Btw - this a spillover system with a fan between boxes if it matters somehow.

Well I have determined the problem is environmental. If the boat is warm/hot and there is a lot of humidity in the air the freezer frosts up pretty fast. Currently I am at a slip with the air conditioning running. Instead of the freezer evaporator getting all fuzzy frosted up it is instead icing up with a solid hard ice layer. The fuzzy frost is a lot more an insulator than the ice.

The answer is to get rid of the spillover system and go to a separate freezer and refrigerator.

Standard "anything on a boat can be fixed with the proper application of cash".