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botanybay · 28-09-2013, 19:03

Working through systems on new to me boat and it is time to chase an annoyance which might be more than that.

Specifically, sometimes the compressor is whisper quiet and at other times makes a "tinny" sound.

Otherwise the boxes pull down nicely.

Of note: there are two independent circuits, one for the freezer with two plates, one for the fridge with one plate. There are independent thermostats and a solenoid for each circuit.

This is a large compressor which is something like 1000 to 1500 watts running. Three loops on the seawater coils, a large receiver. System was installed by Oyster in 1990 during build although the second holding plate looks like an addition as it is an alder barber / Crosby plate, the others are from Grunert.

When I bought the vessel the plates would not get to a low temp and freeze very quickly so I pulled the manual and adjusted the expansion valve in each circuit independently. (Will add the data later) with the other circuit off as directed.

The system works well and until a friend complained about the intermittent noise I had not really noticed it as it is behind cushions. With the cushions out it is very noticeable. With cushions in not so much.

The site glass clears quickly.

The noise appears to be more on startup quieting down after a few minutes. Gets louder if the other circuit kicks in later. The sound is definitely intermittent during operation and is pretty consistent near the end of cycle.

The suction line between the galley and the compressor is not accessible for about 6 feet and then runs about 3 feet. This line frosts rapidly when the plates are cold but need to be run.

Compressor is hot to the touch but I can hold hand against it with discomfort (will measure).

Solenoids for each circuit in the liquid side frost up quickly.

Low pressure side (with plates having ice but needing to pull down) pulls to 8 psi quickly (freezer circuit only) and then heads for 4 psi over the next 45 min or so.

Compressor is rated for 208/230 50/60hz. On shore power it is currently running on 208/60, on generator 230/50. I need to confirm if the pattern is the same on 230/50 as I have to hear it over the generator.

When I got the boat the txv valves were very far open. It looked like many things on the boat had been "tinkered" with. With a more is better attitude. I wonder if the system is over charged but using a touch less temp gauge I think I found the line in the receiver about half way up where there was a change.

The boat was in the tropics for some time with much warmer water than southern california.

I assume the system is R12 but not sure if there is an easy way to confirm.

Any thoughts would be greatly appreciated!

David

botanybay · 28-09-2013, 21:08

Here is a link to the adjustments I made to superheat a few years back:

Fridge and Freezer Superheat Setting

DeepFrz · 28-09-2013, 21:09

If Richard Kollmann doesn't respond to your post you could try contacting him on his web site.
Kollmann Marine

botanybay · 29-09-2013, 11:07

Compressor just kicked in on freezer side only. Noise there for first 10 min then gone. Sight glass clear by the time I got to it less than a minute later.

A month ago I saw a period where the site glass was about 2/3 full but clear fluid below the interface. This was at the very end of the cycle before the freezer plates kicked off.

Smooth whistling noise at plate with occasional gurgling.

Compressor is aj530ft-165

Control box says model 50wz
220v 50/60
80oz R12

Condenser is 5 loops

Noise just showed up after 45 min run time.

Suction line sweating but not frosted

Site glass clear
Suction line goes through heat exchanger which is bottom of the 5 coils. So 4 water to refrigerant coils, one suction to liquid heat exchanger.

Suction side to compressor off heat exchanger cool but not cold (no sweat)

10 min later seeing frost on suction line prior to heat exchanger. Finger will tack to line then goes to sweat when it goes vertical for 4 inches prior to going into the heat exchanger.

10 min layer seeing bubbles occasionally in site glass, frosting to heat exchanger inlet.

Too of first plate froze up.

Sounds more like a rattle which oscillates.

Thermostat is at warmest setting. Perhaps this is normal if the plates are frozen and the thermostat is a bit sticky? I can't find the IR thermometer to check temp.

botanybay · 29-09-2013, 11:58

Cutoff was about 1 hr 30 min for freezer alone.

Fridge side triggered and noisy. Frost on suction line melted immediately.

Site glass clear

Rattle is lower and more hollow. Went away completely after 3 min.

A slight whine or more of a whir with only the refrigeration plate.

Note that there is nothing to prevent both circuits being active at the same time. Just was fortuitous that it was this way when I was here.

Just a whir after a while. More like a soft purr...

Quiet for at least 30 min when I had leave so did not hear the end of the cycle.

Richard Kollmann · 30-09-2013, 06:18

Botanybay, There are no two boat refrigeration system the same which makes it difficult to understand and recommend answers to the conditions you are talking about.

The most common cause of noise from this compressor is aged rubber mounting vibration dampers under heavy compressor that are allowing metal to metal contact when vibration is high under a load.
Noise inside compressor could be refrigerant superheat is too narrow allowing liquid to make a pinging sound as it explodes to vapor as it inters compressor metal dome. I interrupt this sound to be a pinging noise. Frost on return line within a few inches of compressor can damage compressor as it is not designed to pump liquid. . It is also possible the sound heard is from weak springs on the floating assembly inside compressor housing. This sound is a deeper thumping noise and more pronounced each time compressor if working hard and when compressor starts and stops.

With two expansion valves, two solenoid controlled by thermostats and two holding plates there must also be a low pressure switch to stop compressor if suction pressure gets too low and a high pressure cut off switch when water cooling is not adequate. I generally recommend keeping valve superheat at manufacturers preset default setting on holding plate systems. To fine tune super heat I increase or decrease thermo-heat transfer contact between valve sense bulb and low pressure return line. In a dual system like yours I want refrigerator valve to start throttling back as soon as possible so freezer valve can operate at low temperatures instead of waiting on refrigerator thermostat to be satisfied. After maybe 50 dual plate systems I found out that a smaller ton orifice in refrigerator valve also reduced daily compressor run times. There are dual designs that include a low pressure regulator valve to control low pressure in refrigerator plate but not common on US made systems.

To comment on your systems performance I need test data on each box run separately. This requires box temperature and ambient temperatures before start and again at end of a one to two hour test runs. To be recorder in test every 10 minute, Suction and high pressures and a detailed description of where frost or cold is present throughout system. An example, Filter only slightly warm T fitting in liquid line same temp as filter, Solenoids both same temp as filter, Frost on expansion valve, Plate 90% frost cover.
If plate is already cold on start up frost will quickly form on return line as system pumps down, this is because TXV is wide open and plate has liquid refrigerant in its evaporator coil. As TXV temperature sense bulb starts to get cold valve will take over flow control by reducing refrigerant flow. One of the most important recorded items will be frost on return line during the complete test run. Try to get a rough measurement of length of return line frost again every 10 minutes.

botanybay · 30-09-2013, 07:44

Thank you very much for the very helpful feedback. I very much appreciate your efforts!

The observation that it is best to have the fridge throttle back early to allow the suction side pressure to drop and start having the freezer be truely active early in the cycle is quite valuable. At the time I got the system running with the adjustments resulted in a working system, the previous owner had opened both valves nearly wide open thinking that would help (I assume).

Would you recommend running tests with both circuits running in parallel against room temperature plates or working one side at a time for testing?

Can you recommend a recording system which you like? I have been looking at several for some time but can't decide on which one to purchase.

It is clear that both thermostats are getting sticky and need to be replaced. I have seen your recommendation in favor of mechanical thermostats. Is there a variety which have proven to be more reliable than others.

Does water temperature have much if any impact on a system like this? i.e. will winter time water temperatures be acceptable for testing or will I need to pre-warm water to the expected summertime temperatures to get the system tuned up?

I did try applying hand pressure to the compressor, coils and other components to ensure that it was not a problem of old rubber (it is a 25 year old system) causing the metalic noise. I could not get the sound to change applying hand pressure to any part of the compressor assembly. However, it could still be the case and I will monitor. I am not so much worried about the noise itself but rather what it might be telling me.

The frost line on the suction side will get as far as the first upward turn on the compressor (bench / skid / what is the common term for the entire integrated compressor / receiver / dryer / site glass / heat exchanger assembly?) which is a couple of inches into the bench. It goes vertical about 3 inches of which the top two inches is sweating but no frost and then into a heat exchanger between the suction side (cold) and the output of the high pressure side water to refrigerant heat exchanger.

After coming out of the heat exchanger between the high side / low side the line into the compressor runs down about 3 inches, horizontally about 8 inches and then up 6 inches back down 2 inches and into the compressor dome. The entire output of the suction side after the heat exchanger is cool but does not sweat at all.

Would it be unlikely to have any liquid getting to the compressor with that much uphill path length without sweat on it.

I will measure it but I think the pressure on the low side at this point is about 4psi (-10F on the chart). The freezer plate is a 0F plate I think.

I assume the temperature of the filter you mean the dryer between the receiver and the site glass?

Sorry for so many questions.

Thank you again for your help!

Sincerely

David

Quote:

Originally Posted by Richard Kollmann

Botanybay, There are no two boat refrigeration system the same which makes it difficult to understand and recommend answers to the conditions you are talking about.

The most common cause of noise from this compressor is aged rubber mounting vibration dampers under heavy compressor that are allowing metal to metal contact when vibration is high under a load.
Noise inside compressor could be refrigerant superheat is too narrow allowing liquid to make a pinging sound as it explodes to vapor as it inters compressor metal dome. I interrupt this sound to be a pinging noise. Frost on return line within a few inches of compressor can damage compressor as it is not designed to pump liquid. . It is also possible the sound heard is from weak springs on the floating assembly inside compressor housing. This sound is a deeper thumping noise and more pronounced each time compressor if working hard and when compressor starts and stops.

With two expansion valves, two solenoid controlled by thermostats and two holding plates there must also be a low pressure switch to stop compressor if suction pressure gets too low and a high pressure cut off switch when water cooling is not adequate. I generally recommend keeping valve superheat at manufacturers preset default setting on holding plate systems. To fine tune super heat I increase or decrease thermo-heat transfer contact between valve sense bulb and low pressure return line. In a dual system like yours I want refrigerator valve to start throttling back as soon as possible so freezer valve can operate at low temperatures instead of waiting on refrigerator thermostat to be satisfied. After maybe 50 dual plate systems I found out that a smaller ton orifice in refrigerator valve also reduced daily compressor run times. There are dual designs that include a low pressure regulator valve to control low pressure in refrigerator plate but not common on US made systems.

To comment on your systems performance I need test data on each box run separately. This requires box temperature and ambient temperatures before start and again at end of a one to two hour test runs. To be recorder in test every 10 minute, Suction and high pressures and a detailed description of where frost or cold is present throughout system. An example, Filter only slightly warm T fitting in liquid line same temp as filter, Solenoids both same temp as filter, Frost on expansion valve, Plate 90% frost cover.
If plate is already cold on start up frost will quickly form on return line as system pumps down, this is because TXV is wide open and plate has liquid refrigerant in its evaporator coil. As TXV temperature sense bulb starts to get cold valve will take over flow control by reducing refrigerant flow. One of the most important recorded items will be frost on return line during the complete test run. Try to get a rough measurement of length of return line frost again every 10 minutes.

botanybay · 30-09-2013, 07:53

One other observation about the system. It does not appear there is a high or low pressure cutout switch external to the compressor. Is it worth breaking into the system to add one or both?

David
S/V Botany Bay

Richard Kollmann · 02-10-2013, 09:08

Q. Would you recommend running tests with both circuits running in parallel against room temperature plates or working one side at a time for testing?

A. Best test is recommended to do any day after unit froze that box’s plate the day before. Each unit and box will be tested separate then after data is analyzed I will recommend superheat adjustment for each system. Then final test run with both solenoids energized.

Q. Can you recommend a recording system which you like?

A. Refrigeration gauge set with both gauges reading zero before connecting to system.
A tape measure and a watch.

You said seawater was cold so its approximant temperature is also important.

Q. It is clear that both thermostats are getting sticky and need to be replaced.

A. Manual thermostats are the most reliable. A little spray of WD 40 and working knob off and to full cold several times should add a few more years to thermostats life.

Q. After coming out of the heat exchanger between the high side / low side the line into the compressor runs down about 3 inches, horizontally about 8 inches and then up 6 inches back down 2 inches and into the compressor dome. The entire output of the suction side after the heat exchanger is cool but does not sweat at all.

A. Test data from all three test runs should answer this question.

Q. I assume the temperature of the filter you mean the dryer between the receiver and the site glass?

A. Anywhere after condenser and no farther than the T separating the two systems.

I do not ask for sight-glass visual on the first two tests because I am only interested on the third test when both systems are operating.

botanybay · 18-06-2014, 00:44

Below are the notes for a test run starting with warm plates. The system currently only has one circuit. The fridge plate started to bulge I removed it from the system. Sight glass shows no moisture.

Used fluke 561 IR non-contact probe for all temperature measurements.

2014.06.17
Fridge testing. Fully warm.
water temp 70f (perhaps 69f)
plate temp is 71F
compressor body is 73F
compressor body low 72psi (schrader valve)
beyond sight glass high high 75psi (schrader valve)
No ports moved
thermostat setpoint 2
running on inverter at 50hz / 230 v 1360 va / 29.4a x 26.6v = 782 watts
plate says 1/2 hp compressor
80 grams of R12 was factory loaded according to plate

System has two plates in series in the freezer:
plate 1 is 16" x 10" x 3" labeled "freezer Adler / Barbour Crosby"
plate 2 is 12" x 22" x 3" labeled "Grunert"
expansion valve on plate 1 "eaton controls division 223 FA 1/2 9o" (raised 0 or degrees)
sense bulb is on output of second plate

on at 1856
30 seconds in compressor settled down.pumping down
after 30 seconds
low 20/high 125
at 18psi compressor is quiet
60 seconds: settled at 18.5 psi / 138psi
no water flow...
shut down, open seacock!
Restart, got flow...
keeping fridge top open so a little warm air getting into fridge.
1900 startup
1903 11psi / 105psi / condensor coil temp 71F
expansion valve 7.2F
exit first plate 58F
enter second plate 63F
exit second plate 69F
Site glass completely full. Slight tan hint to fluid (some oil mixed in with refrigerant?)

In the following Ctmp first is compressor top, second is outside of cooling coils

Atmp is the temperature of the accumulator just downstream of the cooling coils

exp is the temp just after the expansion valve

p1 L is the coldest spot on the plate
p1 H is the warmest spot on the plate (top of p1 does not appear to have fluid, measured where the frost line starts about 1" below
p1 ex is the tubing temp exiting plate 1

p2 L is the lowest temp on plate 2
p2 H is the warmest temp on plate 2
p2 ex is the bulb temp on the return line

chk is at the check valve about 8 feet back toward the compressor

time | Low | High | Ctmp | Atmp | exp | p1 L | p1 H | P1 ex | p2 in | p2 L | P2 H | P2 ex | chk
1912 | 9 | 92 |121/71| 80 | 3.4 | 66 | 46 | 38 | 58 | 53 | 70 | 68 | 72 very occasional bubbles in glass clear fluid
1923 | 8.8 | 87 |150/71| 76 | 4.7 | 25 | 60 | 4.6 | xx | 50 | 60 | 66 | 72 stationary bubble about 1/3 of glass
1938 | 9 | 86 |174/72| 76 | 4.4 | 22 | 43 | 0 | xx | 15 | 58 | 62 | 74 stationary bubble about 1/2 of glass frost 1" p2 top
1949 | 9.5 | 89 |187/73| 76 | 4.0 | 14 | 38 | 0 | xx | 11 | 58 | 57 | 72 stationary bubble about 1/3 of glass frost 1/2 p2 top
2010 | 10 | 90 |204/72| 77 | 4.6 | 10 | 21 | -0.4 | xx | 5.2 | 57 | 46 | 69 stationary bubble about 1/4 of glass frost 5/8 p2 top
2025 | 10 | 88 |210/73| 78 | 4.2 | 10 | 20 | -0.5 | xx | 3.5 | 51 | 29 | 66 stationary bubble about 1/2 of glass frost 3/4 p2 top
2039 | 10 | 87 |215/73| 78 | 4.5 | 9 | 20 | 0.0 | xx | 2.2 | 45 | 12 | 60 stationary bubble about 1/2 of glass frost top to bottom
2052 | 10 | 87 |216/73| 76 | 4.8 | 7.1 | 19 | 0.0 | xx | 5.2 | 55 | 7.8 | 57 stationary bubble about 1/2 of glass p2 frost 70%
2109 | 10 | 86 |218/74| 76 | 4.4 | 6.2 | 14 | -0.5 | xx | 2.1 | 53 | 7.2 | 49 same
2121 | 10 | 86 |219/73| 76 | 4.1 | 6.0 | 14 | -1.0 | xx | 2.8 | 49 | 6.8 | 40 same
2139 | 9.5 | 84 |217/74| 74 | 2.5 | 5.1 | 14 | -2.5 | xx | -1.1 | 47 | 3.3 | 3.7 check valve now frosted up
2150 | 8.5 | 82 |217/75| 74 | 1.4 | 3.2 | 14 | -3.5 | xx | -1.3 | 44 | 2.8 | 3.9 return line wet
2201 | 8.5 | 80 |216/76| 70 | 0.1 | 3.3 | 14 | -3.8 | xx | -2.4 | 39 | 1.7 | 3.7 whole surface of p2 is frosted
2211 | 8.0 | 80 |216/76| 69 | 0.1 | 2.2 | 14 | -4.5 | xx | -3.6 | 34 | 0.9 | 2.7 note, nut on plate for expansion valve is -1.5F
2222 | 8.0 | 78 |217/75| 69 | 0.0 | 2.1 | 12 | -4.7 | xx | -4.1 | 36 | 0.5 | 4.3
2232 | 8.0 | 78 |216/75| 69 | 0.2 | 2.1 | 10 | -4.7 | xx | -4.1 | 36 | 1.2 | 2.7
2242 | 7.8 | 78 |216/75| 68 | 0.6 | 1.5 | 8 | -4.0 | xx | -4.1 | 33 | 0.8 | 4.8 Note p1 high point is top of frost, plate not full.
2255 | 7.8 | 76 |216/76| 67 | 1.2 | 2.2 | 7 | -3.9 | xx | -4.1 | 36 | 1.5 | 7.0 frost to return stationary bubble has remained
2310 | 7.8 | 76 |213/75| 67 | 0.9 | 1.6 | 7 | -3.9 | xx | -4.0 | 37 | 0.9 | 6.5
closed door
2320 | 7.8 | 76 |214/75| 67 | 0.6 | 1.3 | 7 | -3.9 | xx | -4.7 | 29 | 1.5 | 12
2330 | 7.5 | 75 |215/74| 68 | 1.2 | 1.2 | 6 | -3.7 | xx | -4.3 | 22 | 0.8 | 10
2350 | 7.5 | 75 |214/74| 68 | 1.5 | 1.2 | 6 | -3.9 | xx | -4.6 | 21 | 0.2 | 16
2410 | 7.5 | 75 |212/74| 67 | 1.5 | 1.3 | 6 | -3.6 | xx | -4.6 | 13 | 0.2 | 12
Still won't shut down even at warmest setting. Slowly getting there but not quickly, even after 5 hours of run time... Temp at thermostat bulb is about 11F so would not expect it to turn off yet.

If plates are already cold then system will cycle, first cycle takes forever. Run time for a cycle once cycling is about 2 hours.

I will try and clean up the above table soon.

botanybay · 18-06-2014, 07:28

The first column is time
The Second column is the pressure at the suction tap on the compressor
The second column is the pressure beyond the site glass (on the compressor pallet)

So, with a final pressure (after 5 hrs of run) of 7.5psi -> -3.5F equiv temperature interpolating a chart.

That is almost exactly the temperature of the refrigerant at the exit of the first plate.

The temperature as measured at the bulb for the expansion valve is 0.2F so that would be a "superheat" of just under 4 (-3.5F - 0.2F) = 3.7

According to the manual most of these systems work best with a superheat of about 10 - 12 so that could be a problem.

Sailing Drummer · 18-06-2014, 14:24

botanybay,

I don't know anything about refrigeration but I may be able to help if all else fails. Look at http://www.cruisersforum.com/forums/...em-127530.html . Look at the second post - I've changed how it's being sold. Perhaps part of this system will work for you? If you are interested in any of this let me know.

Larry

botanybay · 18-06-2014, 16:31

Thanks! I will keep it in mind as I work through getting the system to work more like it should.

What was the refrigerant in the system?

I assume that one of the plates is fridge and the other is freezer?

For the freezer there are notches in one of the ears of the plate to denote the temperature of the plate.

Yours looks like the 1/4 hp version of the system?

Sailing Drummer · 18-06-2014, 18:59

What was the refrigerant in the system?

The refrigerant was 409A.

I assume that one of the plates is fridge and the other is freezer?

Yes.

For the freezer there are notches in one of the ears of the plate to denote the temperature of the plate.

Well, at least now I know something about refrigeration!!! Yes there is a notch in one of the ears and it's on the one that was in the freezer. I originally marked in magic marker on the back of the one from the refrigerator so I would know which was which. See picture below.

Yours looks like the 1/4 hp version of the system?

That I don't know. It was on the boat when I bought her and there was no paperwork. It was for a total of 2 cu ft freezer and 4 cu ft refrigerator.