Another Frigoboat Cooling Problem

[skipgundlach]

data points:

System has always been defrosted with a heat gun
System was decommissioned (off extensively, doors off) twice, once in the yard in the summer when we were eating off the boat, and again for a month in Vero Beach in April; evac-recharge was in the first time frame.

I've done repetitive hot-wet on the top corner of the plate; it feels like there may be some rectangular hard point there, but I also stuffed the rag down the back as much as it would go.

[skipgundlach]

After 2 hours, system temps have not moved. 34.0/37.9, about where we started this thread.

Immediately after hot wet rag, temps dropped about 1* /25 minutes. Gurgling sound heard. However very shortly after that, temps back up and no gurgling....

[Frigoboat Info]

Skip: This is getting very difficult to manage here on the forum. I've sent you a private message.

Frigoboat Info

[skipgundlach]

A brief update:

After trying all manner of things, the final conclusion from Frigoboat Info (in off-group emails) after a couple of months of fiddling is that we have some sort of blockage, which should be cured by a technician cutting into the line and soldering on a cap tube filter, and, as well, adding a filter-dryer, both to prevent future reoccurrences.

We proved out the compressor, the keel cooler, the evaporator plate, the door gasketing, added an air cooler, testing both individually and in tandem with the keel cooler, evacuated (-1 Bar nearly 2 days each time) and recharged, twice, all to no permanent avail. When the blockage moves, it cools just fine; when the blockage hits something, all cooling stops and the suction goes to nearly evacuation levels. Successive on-off repetitions eventually dislodges it, and cooling recommences until it clogs again, generally between 24 and 60 hours later. Generally, when the system cycles, it will not restart (well, cool; the compressor runs, the fans on the air cooler and heat sink blow, but the extreme suction prevents cooling) and I do the above for another brief cycle of cooling.

In between the additions above, a nitrogen power flush in hopes of dislodging and removing any existing blockage, evacuation and recharge, by a competent tech in St. Augustine, referred by FI, to where we'll sail when we get the right weather window.

Until that time, impossible (well, we don't want to do it before then) until we fix our GPS' failure to communicate with our other instruments, we'll muddle along with the occasional freezing we achieve acting as a holding plate for the refrigerator, which manages to stay at least cool with all the insulation I built the system with.

More when it happens!

L8R

Skip

[Richard Kollmann]

Skip bad news that you are still out of full use of refrigerator after two months of fighting it. Good news is Frigoboat has fond a technician who can install a filter at inlet of capillary tube. I looked at Frigoboat’s recommended web page upgrade and it is not a repair I would recommend for a DIY project. It is also good news that all future keel cooler units sold in US will have filter screen to protect capillary tube inlet.

I gave up on my sixth edition of books on Boat Refrigeration and decided to post free update revisions weekly on my web site. I Just posted Tech Tip 4 on Danfoss electronic control module options.

[skipgundlach]

The saga has entered another phase.

Clay Hansen, of Hansen Marine Services, recommended a dock in St. Augustine which was literally up the driveway from his office. It so happens that it's VERY affordable (on the order of less than 1/4 that of City Marina) and easy walking distance to downtown, 3 blocks from Sailors Exchange, and so on.

He came to the boat and cut into the capillary tube line which would require fiddly fitting and silver-soldering to install, as well as some VERY inconvenient line locations (nothing to do about that, as it wants to be vertical), and, as well, added a filter-dryer to the line. Curiously, that was immediately after the soldered-in cap line filter, which, since the filter-dryer was the same quick-connect arrangement as the rest of the system, had me scratching my head as to why in the world the cap tube filter didn't have the quick-fit feature as well.

In any event, after that installation, the system was vacuumed for 18 hours, and a static charge was installed. Tellingly, that charge was achieved in a matter of a couple of minutes, whereas mine had taken hours to equalize. Same can, same gauge setup, and so on, but much faster. Sounds good to me!

Surprisingly to me, there was no nitrogen treatment, despite his having gone off to obtain more, Clay having run out of it before our job. The reason was that we were listening closely to the evacuation sounds, and all was as it should be, which suggested free flow. The potential downside to a nitrogen flush is that if there were a piece of debris (for sure we had SOMETHING which moved around, or we wouldn't have had cooling successfully for some number of hours and then the suction pegging negative), it could be forced into a position where it wouldn't move at all. So, we relied on the filter(s) to catch anything which might remain in the system after the evacuation.

We're now in the process of cooling the system. At Clay's suggestion, I bought 30# of ice and loaded it into the freezer. He said we could go ahead and reload the tiny amount we'd had in the reefer side, but I took out all the water I'd previously had in the freezer (for thermal flywheel for the very infrequent occasions when I'd get the system to run). Once we have everything running and cycling (reaches hysteresis) , I'll stress the system by putting the warm water back into a cold freezer to see if anything untoward happens. If nothing then, we'll wait for not less than a week before considering that the system is fixed, having been burned several times by believing constant temperature drops over as much as 3 days meant that the problem had gone away.

Those tracking this know that I now have an air cooler in tandem; Clay recommended leaving it there if we ever were going to be out of the water, but in particular, said that putting a switch in for the fan, unless I was critically concerned about the 0.3 or so A it draws, as, per his comment, "you can never have too much cooling" and even if the gas is ambient temp going into the keel cooler, that's fine, wasn't worth it.

So, we're keeping the air cooler and leaving the fan in the system. If the filter(s) remove whatever it is which was giving us grief in the end, it seems that, for the small added cost in the total system, it would be advisable to include this in new systems. The add-on filter-dryer is perhaps double the size of the one on the compressor, and, presumably, as it's away from the engine, would do a better job (no heat transfer from being right next to a hot compressor) of assuring no moisture going into vapor, if it were caught there; of course, I also assume it somehow would be more effective at catching any debris and/or sludge (water/oil mix) than the installed one would be, as I clearly failed with that as the isolator of junk.

Clay's assessment is that the keel cooler is fine, other than that it may have caused the seal failure I had long ago, now (replacing the O-ring fixed it), due to more heat than normal at the high pressure connection (right next to the compressor), but having the air cooler in line not only will assure performance in the warmest of waters, but allow us to not have to deal with keeping the keel cooler wet when we're on the hard again (as all boats eventually are).

Just the radiant dissipation, I'm sure, would help, but the fan blowing over the air cooler, which is mounted essentially as it would be in the air-cooled versions' single unit, when I remount the protective box over the compressor, will channel all that air over the compressor before, providing some more cooling there (making the compressor happier).

So, we'll know in a week or so, but so far it's looking good...

L8R

Skip

[Richard Kollmann]

Good news Skip, three months without refrigeration now hopefully unit is back in service for good. Was Clay able to find and remove the screen that was engineered in place of a filter to prevent tube blockage? Engineering in Italy insured me in an email that there is a screen. Was he able to install a replaceable filter or is it hard soldered in, as Frigoboat US in their engineering modification instruction sheet described?

[skipgundlach]

Hi, Richard,

The cap tube filter was cut-line silver soldered. The filter-dryer was in-line quick connect a foot further down the tube. No mention nor removal was had of any gear, or filter.

At the moment, with 30# of ice to help bring it down faster, the freezer is at 31.4 and the reefer, including some warm-loaded beverages, is at 34.7, both down from a 70ish start about 10 hours ago. Gauge has been consistent at 6/135-40 all that time.

I believe it's still undercharged based on looking at the evaporator before our ice-load, but we'll let it run for an extended period before we make that judgment, and maybe overcharge...

Thanks for the interest.

L8R

Skip

[skipgundlach]

All those with working Frigoboat refrigeration systems, please take one step forward.

Not so fast, Flying Pig!

... At about 8 hours in, my refrigeration began the slide into its prior behavior; when we returned from meeting a new friend downtown, it had settled firmly on the -22 suction side, where it's resided for the majority of the last couple of months, and +100, as the charge level wasn't nearly as large as I'd put in, before, to try to make it run.

So, we are now relying on the 30# of ice in the freezer to keep things relatively cool as the box temps approach 40 from the wrong direction until Monday when help can arrive again. I'll scoop out the nearly 4 gallons of melted ice when we start working on it again...

[SV THIRD DAY]

At the end of the day out cruising, using water cooling for your refrigeration is just a problem waiting for an anchorage or passage to happen! Not to mention the extra power amps it sucks down. Your best bet is to go with a refrigeration unit designed with a large enough condenser so that is does not require water cooling.

[skipgundlach]

I agree, and would never have put melting ice into my box other than to pull it down more quickly.

Oh. You meant MOVING water, inside the boat. Agreed. That was what we took out to install this system...

[skipgundlach]

The beat goes on...

R-11 flush, nitrogen flush, good flow, but between service port and high pressure port, it probably mostly involved the compressor.

Vacuum, try again. Rinse, repeat. Same pegging of suction side.

Find another evaporator (damaged but unused), replace mine with it (in the engine room) to prove out system with new plate.

Cold, pressures as expected.

Oops. Turn it off, leave for half hour or so, and restart.

Not so fast, 3-blink for not less than 1.5 hours. Leave it running (try to start) while I watch a movie. Why so long to restart, when it had plenty of time to equalize (to 80psig)?

It's running, by the time I stop, unknown time since start. Pressures as expected (16//180, probably overcharged), plate frosted.

Next step attempting to flush/vacuum/nitro-blow, in reverse, the evaporator, now that it's out of the system. Failure to succeed means total destruction of the galley, and it doesn't work now, so we have nothing to lose.

More later as more happens...

[skipgundlach]

Anybody still reading has got to be a masochist, but...

Pictures: Flying Pig Early Refit + Projects/Early_Major_Alterations_Work/03-05/Reefer takes you to our bending, and later, installation of our evaporator. I don't know what the bulbous tube is on it, but it's similar in size and shape as the filter-dryer which we installed to try to remedy my problems.

However it happened, the evaporator's where the problem lay, and is intractable, despite having made up fittings to allow use of the quick-connects (cut off the ends of a dead evap, solder on schraders on the other ends, connect to nitrogen, vacuum, alternately, both directions) to the ends of the evaporator and cap tubes for flushing/blowing/sucking out the evaporator.

Nothing moves either way. That it DOES, ever, after evacuation/recharge , but not for long, is enough to tear my hair out - but the last gasp attempt has failed, as well as, with the test plate immediately cooling, with appropriate pressures, proving out the balance of the system, now, the evaporator being declared dead.

Due to the size and nature of the evaporator and the place it's in, it will have to be cut out to remove it (it's far too stout to bend/crush into the shape needed to fit out the door opening). That, however, soundly beats the otherwise-necessary destruction of the galley and reefer top, along with its door installation.

Current plan is to replace that with a couple of series-mounted plates, perhaps higher mass (not holdover, but not just thin plates), which will allow insertion through the ~1' square door opening before attachment.

Clay is consulting with some others in the business as to what plate to use, and he may just use standard flare fittings for future service ease, let alone combining in the box once they're mounted.

So, we're not finished yet, but it appear$ we're on the home $tretch. I have no concept, as money was never discussed, of how much this will cost in the end, but there have been a great number of man-hours invested to this point, without any equipment other than some flush, nitrogen and R134a.

That this has totally consumed our lives for the last 4 months makes the money part a bit irrelevant, if it can be cured as it seems it must be able to do...

More when there's more to tell!

L8R

Skip

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[Richard Kollmann]

Skip, we all can understand what you have been going through for the last three months trying to solve your refrigeration problem. Others with the same problem eventually give up and replace complete system. Other boaters that replace evaporators have found that flow restriction will occur again but the question is did they also install a filter to protect capillary tube and complete evaporator assembly before putting new evaporator in operation . After reviewing your pictures I realized they ran cap tube through suction line accumulator this may have solved the mystery filter screen if inside, but on suction side not liquid side of system. If Frigoboat is not interested in cutting this unit open I would like to get it as it may be why they wanted to keep protection screen’s location a secret. The primary function of the suction accumulator is to catch and hold any liquid refrigerant that didn’t boil off in the evaporator.

During normal compressor off cycles refrigerant in system will migrate into any cold area. On the next compressor start any liquid or oil mix in evaporator will first be discharged into a storage area (accumulator) and discharged slowly towards compressor. Roll-Bond aluminum evaporators for small refrigerators normally have many circular chambers embossed near end of refrigerant travel through evaporator coils that serve as a liquid area accumulator. A plugged orifice in Frigoboat’s accumulator would be the most likely problem. This plugged orifice would prevent oil and refrigerant from returning to compressor accounting for low pressure in a vacuum instead of normal readings from 4 to 8 psi based on box temperatures you reported. If blockage was at evaporator accumulator outlet excessive amount of refrigerant would have been required to service system instead of the normal 3 to 5 ounces.

One other concern I would have about the accumulator is how cap tube passes through it for sub cooling without restricting return low pressure gas. Hopefully eliminating Frigoboat’s complete evaporator assembly and new filter where there was no filter will be the final fix.

[skipgundlach]

The end of the story is here:

http://www.cruisersforum.com/forums/...or-114081.html