Is there an easy way to refill holdover plates with Eutectic solution

[Richard Kollmann]

Originally Posted by phorvati

Also I have not had failed startup fue to current overload in the last 3 Cycles. Ever since I disconnected the water cooling.

Record Pressure at King valve and low pressure along with liquid lever in glass its 1/3 level now. Also look for frost every where in system including length of ice on tubing coming out of plate. Follow up again in 30 minutes. I would like know after the second readings the total time compressor has run during this test run.
Temperature readings in this test have little value for me.

[phorvati]

Originally Posted by OzeLouie

This system:
When operating during a cooling cycle:
Once started, operation is as normal albeit with abnormally low high side pressure.
When stopped the damaged reed valve allows high pressure refrigerant to pass backwards into the compressor, while low pressure vapour is migrating to the cold evaporator as described for a normal system. (The reed valve damage was determined as the compressor only achieved a 5” vacuum when pumped down during OP’s initial test. A further test to confirm this was requested but no result reported yet)

I just want o be clear. I did not run compressor for long time with valve 2 closed. (High side plugged up). What I said is if I shut valve 2 and shut off compressor. 5" Hg stays at inlet. and 75PSI stays at high side. It stayed that way with compressor shut off for at least an hour. I would be happy to repeat and let it sit overnight. To me that indicates reed valve not leaking.

On the other hand if valve 2 is open and i shut off compressor, 5" Hg goes up to 30PSI within few minutes. and 75PSI high side drops to 45PSI within minutes. That to me means refrigerant was flowing via TXV and cold plates from high side to low side.

[Richard Kollmann]

We should be able to close this thread tomorrow after questioning TXV full orifice opening size and setting super heat for eutectic plate operation and adding additional plate solution if needed.
It looks like again if we had stayed with the facts in the beginning we would have recognized low on refrigerant and Txv exhilarated the refrigerant pump down causing a compressor overload condition.

[OzeLouie]

Originally Posted by phorvati

Also I have not had failed startup fue to current overload in the last 3 Cycles. Ever since I disconnected the water cooling.

So with the head pressure increased the problem did not occur... really, that is what I have been on about? This was not a suction flood problem or restriction issue.

[OzeLouie]

Originally Posted by phorvati

I just want o be clear. I did not run compressor for long time with valve 2 closed. (High side plugged up). What I said is if I shut valve 2 and shut off compressor. 5" Hg stays at inlet. and 75PSI stays at high side. It stayed that way with compressor shut off for at least an hour. I would be happy to repeat and let it sit overnight. To me that indicates reed valve not leaking.

On the other hand if valve 2 is open and i shut off compressor, 5" Hg goes up to 30PSI within few minutes. and 75PSI high side drops to 45PSI within minutes. That to me means refrigerant was flowing via TXV and cold plates from high side to low side.

Still unsure as to your compressors condition therefore..............

Please, test as described in post 33, exactly as described and repeated here...
Test discharge valve reed:
A: Connect suction gauge as in sketch.
B: Close off SVC1 very firmly clockwise.
C: Run compressor for five minutes and note inches of vacuum achieved. (Should reach approx 25" if valve is ok)
D: Switch off compressor and note / time pressure rise. (Pressure will rise a little then remain constant if valve is ok)

Beside the diagram attached I have included a picture of a valve reed and as can be seen, they are very thin and brittle.

Regardless of what you end up doing, I strongly suggest getting your high side pressure to approx 120 PSIG or above for best performance.

This system failure to start issue is not being caused by suction flooding or restriction in the discharge or liquid line to receiver!

[phorvati]

Originally Posted by Richard Kollmann

Record Pressure at King valve and low pressure along with liquid lever in glass its 1/3 level now. Also look for frost every where in system including length of ice on tubing coming out of plate. Follow up again in 30 minutes. I would like know after the second readings the total time compressor has run during this test run.
Temperature readings in this test have little value for me.

ok tonight I'll make a table recording

1. frost on tubing, 2. sight glass level and 3. pressure on king valve, 4 suction pressure. I'll do it on startup and every 10 minutes during 1 cycle.

[phorvati]

Originally Posted by OzeLouie

Please, test as described in post 33, exactly as described and repeated here...
Test discharge valve reed:
A: Connect suction gauge as in sketch.
B: Close off SVC1 very firmly clockwise.
C: Run compressor for five minutes and note inches of vacuum achieved. (Should reach approx 25" if valve is ok)
D: Switch off compressor and note / time pressure rise. (Pressure will rise a little then remain constant if valve is ok)

Attachment 238229

for D, How long does pressure need to remain constant before i conclude reed valve is OK. minutes hours or days? because i had it remain at 5" Hg for 3 hours. but from I what i can gather 5" is not aggressive enough. to really test I would need to stress it so get it to 25" or whatever it gets to with SVC1 closed. I will do that and report. Thanks.

[OzeLouie]

Originally Posted by phorvati

for D, How long does pressure need to remain constant before i conclude reed valve is OK. minutes hours or days? because i had it remain at 5" Hg for 3 hours. but from I what i can gather 5" is not aggressive enough. to really test I would need to stress it so get it to 25" or whatever it gets to with SVC1 closed. I will do that and report. Thanks.

With SVC1 closed the comp should be able to pull down into vacuum within minutes, so leave running for say 5 to 10 minutes where it should be able to get to approx 25" if OK, note the inches of vacuum achieved, switch off compressor and note any pressure rise and time over the next ten minutes.

If the comp still only pulls 5" of vacuum then it is faulty. (should get to at least 20")
If the comp pulls say 25" but if within a few minutes after switching off, the pressure rises to above zero PSIG then the comp is faulty.

Any 'hands on fridge tech' will be aware of this test method and agree that a comp that can only pull a 5" vacuum is stuffed, although if the problem is proved to be a cracked valve reed (most likely) you may still get years out of it albeit working at less than its proper ability besides at 1/2HP it is grossly oversized so you can afford a bit of performance decline!

[phorvati]

Originally Posted by OzeLouie

With SVC1 closed the comp should be able to pull down into vacuum within minutes, so leave running for say 5 to 10 minutes where it should be able to get to approx 25" if OK, note the inches of vacuum achieved, switch off compressor and note any pressure rise and time over the next ten minutes.

If the comp still only pulls 5" of vacuum then it is faulty. (should get to at least 20")
If the comp pulls say 25" but if within a few minutes after switching off, the pressure rises to above zero PSIG then the comp is faulty.

Any 'hands on fridge tech' will be aware of this test method and agree that a comp that can only pull a 5" vacuum is stuffed, although if the problem is proved to be a cracked valve reed (most likely) you may still get years out of it albeit working at less than its proper ability besides at 1/2HP it is grossly oversized so you can afford a bit of performance decline!

So it only pulled 10", 5 minutes into it. Based on this, cracked reed valve. But it's working fine as I get solid frozen ice cream. And it only takes 2-3 hours for freezer to drop from 19F to 11F. My sesnor is not attached to the plate. In the offseason, I will consider replacing with a more forgiving compressor, like what you thought I had earlier, I think you said vertical rotary.
I might get one and have it be ready in case things stop working.
I still need to observe glass and note the frost. I will report on that. As far as high side blockage, I need to Crack open the refrigerant side and sweat in the new fitting. Considerable work to get the high pressure reading now that we have moved onto the boat.
Here are few cool pics with flir.
First one is in the freezer box.
Second is dry heat exchanger, still cooling refrigerant considerably,
Third is compressor output, and suction accumulatornon the left side.
Fourth one is hot refrigerant line and receiver behind it which is basically room temp. To the left is compressor.

[OzeLouie]

Yes only able to pull 10" of vacuum confirms my diagnosis, but not all bad! I have seen compressors keep going for many years with a cracked or buckled discharge reed and given that your comp is grossly oversized, you could still get a lot of use out of it yet.
Getting the high side up and maintaining at / above 120PSIG will assist start up and improve performance and needs to be your priory before trying to set the systems refrigerant charge and TEV setting.

Suggest having a replacement comp on hand but not a rotary as rotaries for low back pressure function can be rather temperamental!!! Look for an approx 10cc LBP R134a compressor preferable with capacitor start as capacitor start is more forgiving of power supply issues.

Not sure what the logic is regards discharge restriction causing failure to start, just does not add up!! If there was a restriction it would impede running not start up, the opposite to your experience!

[Richard Kollmann]

Information in post 47 proved there was no restriction to flow. It also confirmed refrigerant volume in system was too low maybe as a result of low ambient temperatures. Replacing compressor is premature based on a theory. Experience on a hundred properly designed holdover plate systems will confirm the present 1/2 HP 120 volt compressor or larger is correct capacity, just ask SeaFrost.
As far as I can see the test of compressor read valve proved nothing but adding refrigerant might eliminate the reed valve theory.. Under these test conditions and discharge pressure of 100 psi most engineers would believe compressor was in good condition. If you have seen spring flat steel reed valves in 1/2 HP hermetically sealed compressor they do bend and if damaged will leak. After adding refrigerant and controlling condenser cooling medium temperature, A 24 hour performance test of refrigeration cycling will prove or disprove all theories. I will say again on that system as it is cold weather now do not service refrigerant to a high pressure over 120 psi.

[OzeLouie]

So Richard, you have dropped your restricted discharge theory, well done!

Now as someone who has actual hands on experience and is qualified, let me respond to your last post .

1: Any manufacturer who puts a 1/2HP compressor on a project like this needs to sack their 'engineer!
2: The test advised to check the discharge valve is the industry standard, not a theory, which anyone with hands on experience would know!. Or have you read about an alternative test that the industry is unaware of?
The test proved that the compressor could only achieve a 10" vacuum so are you saying that that is ok? Really!
3: The OP advised that the high side was only 60 - 70 PSI, far too low for proper performance and should be maintained to at least 120PSIG, something else that any hands on refrigeration person knows. I am surprised that you are unaware of the need to maintain a proper high side pressure!

(Surely you aware that the test conditions and data manufacturers quote for nearly every reciprocating compressor ever made for use with R134a, is head pressure of 55C or up to and above 200PSI!)
The industry teaches techs to feel the filter dryer and it should be slightly warm, a little above body temp or 100f (38c) or 120PSIG so not sure where you get your ideas from!!
Richard, if you need further help understanding this you may prefer to PM me and I will happily assist.

The OP simply needs to maintain the condensing temperature as I previously described before topping up refrigerant, adjusting TEV, checking the power supply and hope the compressor keeps pumping.

[Richard Kollmann]

Hear are my compressor failure Caveats to the above unprofessional armature posting, low refrigerant volume, the lack of high pressure, and the unlikely crack in high or low pressure reed valves,and another never ending caveat of replacing compressor, while in a very cold climate recommending higher than normal pressure of above 120 psi knowing expansion of refrigerant and inefficient compressor cooling when exposed to warm weather will occur. Another caveat about a smaller compressor to consider when all energy to quickly freeze a eutectic holding plate in less than one hour must come from compressor’s capacity. What if system is ever to run on a 12/120 volt inverted when ships AC power is not available?

[phorvati]

Originally Posted by OzeLouie

So Richard, you have dropped your restricted discharge theory, well done!

Now as someone who has actual hands on experience and is qualified, let me respond to your last post .

1: Any manufacturer who puts a 1/2HP compressor on a project like this needs to sack their 'engineer!
2: The test advised to check the discharge valve is the industry standard, not a theory, which anyone with hands on experience would know!. Or have you read about an alternative test that the industry is unaware of?
The test proved that the compressor could only achieve a 10" vacuum so are you saying that that is ok? Really!
3: The OP advised that the high side was only 60 - 70 PSI, far too low for proper performance and should be maintained to at least 120PSIG, something else that any hands on refrigeration person knows. I am surprised that you are unaware of the need to maintain a proper high side pressure!

(Surely you aware that the test conditions and data manufacturers quote for nearly every reciprocating compressor ever made for use with R134a, is head pressure of 55C or up to and above 200PSI!)
The industry teaches techs to feel the filter dryer and it should be slightly warm, a little above body temp or 100f (38c) or 120PSIG so not sure where you get your ideas from!!
Richard, if you need further help understanding this you may prefer to PM me and I will happily assist.

The OP simply needs to maintain the condensing temperature as I previously described before topping up refrigerant, adjusting TEV, checking the power supply and hope the compressor keeps pumping.

This stuff is not usefull, it would be very usefull to explain where the 120psi optimal pressure came from. I'm an engineer, designed electronics my whole life. I have the capacity to digest useful information and your explanation in technical terms. Just don't skip stuff as I am not hvac technician. The issue i find with refrigeration is that web is littered with hvac related operation and science as well as commercial refrigeration. For Marine refrigeration with holdover plates, there is very little usefull stuff. Richards book on diy refrigeration was very good and better than anything else out there you can find on marine refrigeration. Not commercial, not hvac, or air conditioning.

[Richard Kollmann]

Your question (This stuff is not usefull, it would be very usefull to explain where the 120psi optimal pressure came from.) The 120 psi high pressure is only a optimum red line for this system at its present temperature pressure conditions and not cause of any compressor or refrigerant flow problem. Adding some refrigerant raising flow level in horizontal sight glass to 5/8 full with super heat back to manufactures 1/5 ton setting performance test results should be good. The red line of 120 psi is intended to compensate for cool climate and refrigerant volume changes at temperatures at stander day and warmer. Having designed a number of these ½ HP poorly cooled compressors installations desirable high pressure is best above 105 and normal operating 120 psi. It will not be unusual to see the red line exceeded freezing a warm solution first time on a hot day. Where the confusion in eutectic plates come from is most boaters operate them as cycling evaporators and not all day holding energy storing plates. The purpose of energy storing eutectic tanks is to store surplus energy but small compressors rarely do they produce no surplus energy.

If you want more history of systems like yours read on I hope I answered the question.

Of all the engineering disciplines Mechanical engineering involving refrigerants is the most difficult because of the variables. Mobile refrigeration the way we design ice box conversion system generally violates text book refrigeration. When it comes to the problem here a eutectic solution intended to store energy plate where the inside evaporator will not be at a stable temperature. Normal evaporators in refrigeration and air condition operate in a relative stable temperature allowing design engineers to balance engineering of a system based on specific conditions. Stand alone cabinet refrigerator are normally designed for standard day temperatures of 69 degrees F.

It is unlikely that there will every be two mobile ice box conversion exactly the same especially today because the design and application engineers are in most cases boat owners. The standard for today’s pleasure boat energy holding eutectic plate refrigeration came from these refrigeration companies, Crosby, Gurnert, SeaFrost Technautics and Frigoboat. At the same time Adler Barbour and others experimented successfully with smaller 12/24 volt refrigeration.

Crosby and Grunert copied ideas from supermarket stand alone compressor condensing units for both their engine drive refrigeration and water cooled Hermetically sealed compressors. SeaFrost also used ½ to slightly larger compressors and most of these seal compressor failed to over heating, Oil coolers were tried and even water jackets were tried.