High current? Vitrifrigo top-loading freezer

[DougMc]

Our Bene Oceanis 45 has a Vitrifrigo top-loading freezer model number BN85BT *BNT*.

I suspect this model designation applies to the Beneteau version, because I am having not much luck tracking down info.

In any case, it has a Danfoss BD50F compressor running at 12V, though the info plate says 12-24V. The information plate shows 4.4/2.2 Amps and so I'm presuming the 2.2A applies to 24V operation.

In any case, this unit is drawing more like 8 amps when running, and it seems to run with a very high duty cycle. It has had more than one evacuate and fill due to leaks, so I am concerned about contamination, and maybe lack of lubrication? (The evaporator plate does get frost-covered fairly quickly).

That's the first problem: High current when running.

Furthermore, this freezer has a rather small evaporator plate. We have been told that these units normally have a larger "wraparound" evaporator and so, a small evaporator, even if properly cold, may struggle to get down to the thermostat set-point, leading to very high duty-cycles.

That's the second problem: High (close to 100%) duty cycle.

Together, these problems dominate our power use and so we are using the thing as and ice-box with pump-out....

I hate to throw things away, but with the constellation of concerns, I am contemplating a replacement. But, if all that's needed is a *proper* evacuate and fill, then that would be great..

Advice appreciated.
Doug.
P.S. Is there lubricant added separately from the coolant in these systems?

[Tin Tin]

Danfoss BD 50 is a solid long lasting unit. Refrigerant must be exactly right, not too much not to little. If leak repairs are carried out on the boat, the mechanic needs to come back next day to re-test. He should have resoldered the leak (usually at the quick connect fittings) and inserted a new filter plus 100% evacuated it and replenished with new gas. On a floating platform with such tiny quantities it is difficult to get spot on in a short space of time. Next time remove fridge and take to a workshop. There is also a compressor speed chip that can be inserted on the controller bottom pin that can either slow down (less amps) or speed up the compreesor (more amps , more cooling/freezing) Mechanic bill should only be about 10% of new fridge price. I am not a fridge mechanic only repeating what a work shop did for and explained to me and he was right. - Good Luck

[Bowdrie]

With those units I generally recommend the largest evaporator one can reasonably fit.
The larger surface area absorbs the heat in the box faster.
An 8-amp draw? Something isn't right, that's for sure. Is the compressor running real hot, is the fan working properly?
Is the unit really well-ventilated or does it stew in its own hot air?
Are you sure that there are no leaks?
Did the tech actually weigh-in the charge, either by scale or using a graduated charging cylinder?
The graduated charging cylinders are best, trying to weigh a few ounces using a scale is not so easy on a moving boat.
Last but not least, did the tech use the proper refrigerant?
As in if he inadvertently used a refrigerant that condenses at higher pressures than 134A does.
It would be interesting to know what the high side/low side pressures were when the unit was operating.

[SailingHarmonie]

More than one evacuate and fill... that's always suspicious.

Was the leak actually fixed? Are you SURE? The issue you have can come from two sources. Too much refrigerant, allowing liquid back to the compressor. This is very likely to damage the compressor before too long. If there is frost on the line outside the box returning to the compressor, there is too much gas in the system.

It can also be caused by a leak on the suction side of the compressor, allowing air, and other "stuff" that shouldn't be in there to enter. The accumulating air raises the discharge pressure to much higher than normal levels, leading to higher than normal power usage.

Same thing from a clogged, or partially clogged capillary tube. This can cause very high differential pressures across the compressor, again resulting in higher power draw. This does usually result in poor, or zero, cooling.

If the person who worked on this charged the gas in one go, and called it good, there is a much better than even chance he got it wrong. A capillary system can not be charged by pressure. Theoretically, it can be done by weight, but we are talking a total charge for a small evaporator of less than 50 grams--extremely difficult to get right in the field.

Adding gas a bit at a time, waiting 10 minutes for things to stabilize, and then adding a bit more until the frost line on the evaporator JUST reaches the outlet is the best approach. This takes time, so most mechanics are reluctant to do this, and they take shortcuts.

The oil in these systems does not leak out with the gas. There is never a need to add extra lubricant. The gas used should ONLY be pure R134a. No oil, no additives, no leak stops, nothing.

It is extremely difficult to find competent refrigeration guys to work on these small systems. I suspect that most guys who are good quickly graduate to larger commercial systems where there is a lot more money involved.

I think the idea that a mechanic can fix a problem system for "10% of the cost of a new system" is just crazy. A new system is going to cost ~2K, How long do you expect a mechanic to work for less than $200???

[Tin Tin]

Originally Posted by SailingHarmonie

More than one evacuate and fill... that's always suspicious.

Was the leak actually fixed? Are you SURE? The issue you have can come from two sources. Too much refrigerant, allowing liquid back to the compressor. This is very likely to damage the compressor before too long. If there is frost on the line outside the box returning to the compressor, there is too much gas in the system.

It can also be caused by a leak on the suction side of the compressor, allowing air, and other "stuff" that shouldn't be in there to enter. The accumulating air raises the discharge pressure to much higher than normal levels, leading to higher than normal power usage.

Same thing from a clogged, or partially clogged capillary tube. This can cause very high differential pressures across the compressor, again resulting in higher power draw. This does usually result in poor, or zero, cooling.

If the person who worked on this charged the gas in one go, and called it good, there is a much better than even chance he got it wrong. A capillary system can not be charged by pressure. Theoretically, it can be done by weight, but we are talking a total charge for a small evaporator of less than 50 grams--extremely difficult to get right in the field.

Adding gas a bit at a time, waiting 10 minutes for things to stabilize, and then adding a bit more until the frost line on the evaporator JUST reaches the outlet is the best approach. This takes time, so most mechanics are reluctant to do this, and they take shortcuts.

The oil in these systems does not leak out with the gas. There is never a need to add extra lubricant. The gas used should ONLY be pure R134a. No oil, no additives, no leak stops, nothing.

It is extremely difficult to find competent refrigeration guys to work on these small systems. I suspect that most guys who are good quickly graduate to larger commercial systems where there is a lot more money involved.

I think the idea that a mechanic can fix a problem system for "10% of the cost of a new system" is just crazy. A new system is going to cost ~2K, How long do you expect a mechanic to work for less than $200???

Because that is what it cost me, in fact the first guy was a mobile mechanic charged me $200USD to repair a 2 drawer Vitrifrigio DB50 resoldered, new filter new gas in the boat, no removal. He however was too quick and system with the gas never realy settled so 6 months later I was about to throw the unit out, took it to a shop, he charged me $200USD and re did it all - replacement price of unit is $3000USD + taxes - this was a just over a year ago and its has been running 24/7 ever since. So not as crazy as you "assume". The price included minimal parts. I did all the heavy lifting, disconnect, removal re-install, he did the techical side on his bench, along with a shop full of RV fridges sitting in line getting the same treatment. It is a joy to work with people that really know their stuff and don't rip you off because it is a marine unit.

[more]

BD50F consumation from 2.07A to 8,67A + consumation condeser,evap
all depend rpm compressor and temperature.

99,99% you overcharge compressor.

leave compressor to work and in charging post conect pressure gauge. pressure must be 15-18 PSI
relase gas to this value 15-18 PSI.
or recharge again with R134a, 145 gram or less

[DougMc]

Originally Posted by more

BD50F consumation from 2.07A to 8,67A + consumation condeser,evap
all depend rpm compressor and temperature.

99,99% you overcharge compressor.

leave compressor to work and in charging post conect pressure gauge. pressure must be 15-18 PSI
relase gas to this value 15-18 PSI.
or recharge again with R134a, 145 gram or less

Thanks for the info. It seems quite possible this may be the case. The person who worked on it is a good mechanic, but certainly not a refrigeration specialist.

[DougMc]

OP here:

I got hold of a thermocouple and have measured the cold plate getting down to only about -3C at best. That doesn't seem very cold...

There is an audible "gurgling" sound from the cold plate. Does this give any clues?
Doug

[DougMc]

And, after some minor dismantling of cabinetry I have been able to expose the compressor. The voltage at the compressor (when running) is 11.4V, so a bit less than a volt of drop in the wiring. Probably ok, I'm guessing.

There is a thick layer of ice forming on the tube heading back to the compressor, probably for about 2 feet of it, out of maybe 3 ft. (Hinting at overcharge?)

The compressor is quite warm, about 53C, and the condenser fins about 40C. I'm not convinced the fan is blowing very well (I'll look into that next) but the air temperature here today is 31C.

Lacking gauges, I'll soon be out of stuff I can do myself unless I am able to get a tech to come to the boat.

Any recommendations in Sint Maartin?