Another Frigoboat Cooling Problem

[skipgundlach]

We have the stainless-clad, largest plate, formed to our freezer. It's worked fine for about 8 years, until recently.

We had a small leak which was remedied by installing a new O ring; we then evacuated for a day and recharged.

Initially it seemed under charged; I wound up massively overcharging. Ice formed all the way to the compressor, and box temps weren't very cold.

Bleeding until the ice disappeared cured the problem and all was well.

However, I recently had to do some work on the gaskets, so decommissioned for a bit. Reinstalled the doors and now have never achieved the prior level of cold.

We have Carel digital thermostats set for 8 and 32 degrees, and use a spillover fan to make it happen.

The system now runs full time, and generally the freezer never gets below 20 nor the reefer less than 39. And, aside from when we've warm-loaded something, they don't go up much, either.

The gasket replacement had a problem which we thought was the solution; it let a great deal too much warm air into the box and the freezer was full of snow. Remove the door (stuff with a quilt), remedy the gasket issue, replace the door, defrost and restart.

No change.

I've been paying attention to the return line; it was cold (and in this very humid area, very wet) well over a foot from the bulkhead.

Hm. That looks like an overcharge. Bleed the system. Rinse, repeat, over about a week. The level of cold on the return line is shrinking (now perhaps 8"), but the freezer and reefer aren't changing.

We're in warm (~86) water, but were the first time we ran after the recharge. However, day and night temps have risen at least 10 degrees.

I've read several other threads about problems with a frigoboat but none seemed to appear like this.

Could this behavior be either moisture or contaminant blockage?

Or, perhaps something else?

Thanks.

L8R

Skip, currently lying St. Marys GA

[Richard Kollmann]

Skip, Saw you were anchored in the lake, tried to boat over to see you but by the time I got there you were gone.
Frigoboat Info, watches this site so hopefully he can help solve your problem.

[skipgundlach]

PS

Temps at

Pressure fitting - 130°F
Compressor - 165°F
Cold line with insulator at bulkhead - 60°F

Also evac/recharge/overcharge was after Oring replacement

[Richard Kollmann]

Skip, What is temperature of refrigerant line after it leaves keel cooler?

[skipgundlach]

Originally Posted by Richard Kollmann

Skip, What is temperature of refrigerant line after it leaves keel cooler?

I'm not sure where you mean to measure it.

The line from the KC joints to the compressor high side (with the schrader); that's what I measured.

The line in (presumed suction) is (touch) ambient temperature of 80-90 or less (sometimes feels cool, never condensation.

L8R

Skip

[Frigoboat Info]

Skip: I think I know what's going on here, and it has nothing to do with blockages. You have said that the system worked well out of the water, and although it may perform adequately that way, without any cooling water the temperatures on the components and materials will be excessive, and far above their design limits. We have seen that under such high temperatures, the head gasket in the compressor can burn through and there will not be sufficient differential pressures for the system to function properly. There is a hint that this may be the problem in one or two of the pictures of your compressor, where the label on the side is not a crisp white color as it originally was, but a pinky/brown. My guess is that the label on the top of the compressor is the same shade. There is another clue in the deformed o-ring, which is on the discharge coupling, and this will have been excessively hot if the system was run out of the water.
I see you have gauges, so there is a very simple test to determine if your compressor is performing properly. With the gauges connected, back off the suction coupling at the compressor so that the internal valve closes. Then run the compressor and see what suction it will go down to. If the valves and head gasket are OK you should get down to 20+ in Hg in 5 or 10 minutes, but if these have been damaged, you may not even get into a vacuum. If the valves were bad from having being flooded with liquid refrigerant from a massive overcharge, there will typically be no differential pressure at all, and so not even minimal performance, so I don't think this is your issue.

Frigoboat Info

[skipgundlach]

FI, thanks for that.

I presume I should have the system turned off for a while to let pressures equalize, before doing the suction test, bleed some 134 through the line to purge it and then connect, with the valve closed, to restart and measure suction?

L8R

Skip

[skipgundlach]

Originally Posted by skipgundlach

PS

Temps at

Pressure fitting - 130°F
Compressor - 165°F
Cold line with insulator at bulkhead - 60°F

Also evac/recharge/overcharge was after Oring replacement

Added PS - I just got out the burgers, and shot the evap - it's 13°F, covered with snow after less than a week from defrost...

Freezer 24 and reefer 38 before several openings for dinner; now 27.6 and 40.7...

You can see the new gasketing in the 2011-2012 refit gallery, last minute stuff.

[Frigoboat Info]

Ah. You've put me on the spot here, Skip. I presumed that, as you had a guage set, vacuum pump, etc. that you were trained, licensed and conversant with servicing refrigeration systems. Dependent on which side of the fence you sit, it's either called BS or saving the planet, but unfortunately we cannot give you guidance when it comes to hooking up guages, adding or recovering refrigerant, etc. I sincerely hope that you and others out there understand our position on this. It's not that Frigoboat and other manufacturers are being cagey or protecting our interests, etc., it's simply a matter of abiding by the letter of the law and acting in the best interest of customer safety. But .... I see no problem with what you propose.

[skipgundlach]

I was really just checking sequence, and that I should relax the system before disconnection and gauge connection/vacuum measure...

[Frigoboat Info]

Skip: Snow is definitely not a good sign. That indicates that there is a lot of humid air entering the box, and that can only mean that cold air is escaping. The colder the air gets, the denser and heavier it gets, and so the air in the bottom of a good (Frigoboat) freezer will be looking for any way to escape out of a weak seal or, heaven forbid, an open drain or some other opening. Stop the cold air escaping and you stop the humid air entering and you stop the excessive frost build-up. A light coating of hard frost over a long period is a good sign. Wet, heavy, snow in a short time span is not a good sign.

[skipgundlach]

This is very dry, light, snow. Brushes right off the box when I remove it to fetch a burger...

[skipgundlach]

Originally Posted by Richard Kollmann

Skip, What is temperature of refrigerant line after it leaves keel cooler?

The out tube is encased in plastic, so I can’t readily judge that at the KC. However, the inline at the KC is upper to mid 80s if my gun caught it right (nothing higher in that area).

Joint between return and evap-in is cool to the touch. I don’t know why it would be that we’d lose that much (from 135 to 85, e.g.) between compressor and KC but it’s definitely not a challenge to hold the pressure line at the hull, whereas I’d not like to hang on to the joint at the compressor.

FWIW, I had a closer look at the labels; I don’t know what a new one looks like, but these don’t look compromised.



I messed around long enough that I got the SSC to manual-low; we’ll see if that has any effect, as well.

I'm just waiting for confirmation from HI before I check the vacuum, which I presume should be done with the compressor at high speed.

L8R

Skip

[Frigoboat Info]

Don't hang around waiting for my say-so, Skip. Let's get that compressor tested so that we can either condemn it or move on to the next step.
To set and change speeds manually on the SSC, you press the button until the "Manual" LED lights up then release. Then press it momentarilly to change speeds. These will be ascending, and then reverting to 1 from 6.

[skipgundlach]

Originally Posted by Frigoboat Info

Don't hang around waiting for my say-so, Skip. Let's get that compressor tested so that we can either condemn it or move on to the next step.
To set and change speeds manually on the SSC, you press the button until the "Manual" LED lights up then release. Then press it momentarilly to change speeds. These will be ascending, and then reverting to 1 from 6.

Thanks. I'm going to give the system a while on low to see what happens; then I'll do the suction test.

Any possibility that running it with joint open would suck in outside air?

L8R

Skip