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

[OzeLouie]

Originally Posted by phorvati

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.

Not sure why you find the information provided as 'not useful' Also as an engineer you would operate within industry proven guidelines and practices which is exactly what I provided you with from a refrigeration perspective.

I am suitably qualified having completed a four year refrigeration apprenticeship with Ozefridge Industries, Engineering with RMIT (Topped my group!) a member of ARC, and involved for many years hands on in the engineering, design, build and servicing of nearly 9000 systems mostly DC marine eutectic. So surely I am in a position to quote industry recognised procedures. There are many pictures, data etc as evidence of my industry involvement..

Reference to condensing.
As RK stated various environments that are somewhat unique to marine systems are a major problem. With temperature and pressure being related, any change in condenser (discharge) temperature has a major effect on a systems ability to pump heat away from the cabinet.
Excessively high ambient, (Under condensing, usually 40C + when air cooled only, which relates to a condenser temp of at least 55C) will see the head pressure exceed 200PSIG. The compressor power consumption increases and therefore become less efficient but more importantly may fail to condense hot gas into liquid exacerbating the problem and eventually failing.

Low condenser pressure / temperature.. Over condensing.
Again the problem is environment induced as cold climate will cause over condensing which presents as two major issues. One, the refrigerant flow through the system slows and can all but stall showing up as short of refrigerant, low suction and head pressure. The second issue which may be relevant here is that the comps reed valve relies somewhat on head pressure when stopped to keep it slammed closed. Now with a potentially cracked or bruised reed that may be more important as your system is grossly over condensed.

Like no doubt as with the electrical systems you are involved with, refrigeration systems are engineered to operate within parameters and those parameters are specific to the application although the fundamentals of refrigeration are the same no matter how it is applied.

Refrigeration systems are engineered to operate within optimum parameters and any thing outside those will see detriment to or failure of performance and that is why the systems I build have twin two speed fans thermostatically controlling the condenser temperature. (Plus water cooling also thermostatically controlled if needed to prevent under condensing)

I have to agree there is very little up to date info regards DC marine systems and why our web site and those of other actual system manufacturers contain so much technical info.

I hope this helps.

[Richard Kollmann]

Phorvati, You now have two detailed answers to your question so you must decide re- commissioning process from information learned or look for third party advice.

[Richard Kollmann]

Phorvati, Hopefully by now you had the time to add refrigerant and turn TXV back to manufacturer’s original setting. If you have received advice from others like Technautic’s U tube video confirmed that vacuum of 5 to 10 inches rules out a reed valve problem. I do not know what edition of my four DIY edition books you have but each one will have a chart to fill in for a eutectic holdover system like yours. You will notice high pressures are kept low 105psi to 120psi. in order to provide adequate compressor cooling through out a compressor cycle. You can also see from the low pressure profile 20 psi down to 3 psi how a 70 degree F temperature day will freeze a three gallon plate in one hour and ten minutes.

It will be interesting to see the performance figures of your TXV pressure flow controlled system after correcting high and low pressures by adding refrigerant, resetting TXV, increasing condensers cooling medium temperatures. Correctly balanced your refrigerant flow will never see low performance figures in a vacuum of 5 to 10 inches.

[OzeLouie]

The OP requested help resolving a compressor fail to start problem (post 6) due to suspected compressor flooding / lock up. (Although also could be a power supply problem and not the actual system as many of us here suggested)

This system has issues, but not insurmountable. It is grossly over condensed as indicated by temp in / out of condensers reported (See post 10) and low head pressure indicates. No condenser sub-cooling!! Suggest studying a Pressure - temp card or view:

https://www.youtube.com/watch?v=i29nDp6sRac

for confirmation of condensing pressures.

Also it most likely has a damaged compressor discharge valve reed. (As confirmed by it's inability to pull down a vacuum below 10" with suction CLOSED.) And again any tech who believes a compressor only pulling 10" of vac with closed suction is ok, should not be in our industry!
These issues need to be addressed first especially increasing condenser pressure to at least 120PSIG as that is an easy fix.
As I earlier suggested it may be that the comp can continue on for years albeit with reduced performance.

Suggestions that being low on refrigerant or that a restricted discharge is causing failure to start, are totally wrong.
BTW, Richard, Do you have a link to "Technautic’s U tube video confirmed that vacuum of 5 to 10 inches rules out a reed valve problem.? Thanks.

[Coolerking]

Actually, you close the receiver and then pump it down.
Don't close the suction valve..
You are reading the pressure there.
All the refrigerant is stored in the receiver and then the system should pump down to at least 15 inches.

[OzeLouie]

Agree, you can check comp valves etc by closing off receiver and pumping the system down but that is a slower version of the same thing as shutting off the suction at the comp SV and reading vacuum achieved. Shutting off the SV at the comp quickly allows read of the comp only and is not effected by system refrigerant that may be still slowly 'boiling off.
The method I described in post 33 is correct.

[phorvati]

Originally Posted by OzeLouie

Agree, you can check comp valves etc by closing off receiver and pumping the system down but that is a slower version of the same thing as shutting off the suction at the comp SV and reading vacuum achieved. Shutting off the SV at the comp quickly allows read of the comp only and is not effected by system refrigerant that may be still slowly 'boiling off.
The method I described in post 33 is correct.

Attachment 238724

When i closed suction valve my gauge was on the compressor side. I was making correct measurement.
I made one additional change, and have few more cycles of runtime. instead of packless valve 2, I added a solenoid. I can still repalce filter dryer. So now whenever compressor stops, solenoid is shut off and liquid cannot migrate from receiver to the plates and supposedly past the plates overfiling suction accumulator and flooding.
So with that setup, once set point was reached and compressor shuts off, suction side remained in vacuum for a while. However I learned that if I leave the unit shut off for 12hours, suction pressure still goes up from vacuum to 30psi, and i still get start condition where it draws 40A and 10A circuit breaker trips. The moral of the story, don't let compressor be shut off for a long time.
To get out of it, I have to let out some refrigerant, from suction side for few seconds or at least until suction goes down to 10-20psi. Then it starts.
I used to have 1/3 sight glass. Once I made a solenoid change i felt pretty good that I might have fixed my issue and added refrigerant to about 1/2 full glass at steady state. This also brought my high side at king valve to just over 100psi. Still only air/fan condenser.

So I am pretty sure reed valve is cracked. And thats how liquid migrates to suction side. Slowly over time.

One other thing I didn't hammer on is the dumb ptc start relay that is inside this cheap compressor. I should change it to starting coil instead of ptc. There are some weird things with ptc. It appears that compressor heat is enough to disable it. So if you shut compressor, ptc needs a long time to cool off before you can start compressor again. And if i try to start it while ptc is still hot, i get 40A and compressor not starting. Ptc should shut off as a result of self heating and that should be long enough to get compressor to run. Ptc should not be relevant once compressor is running. Compressor heating should not disable PTC.

[Coolerking]

The refrigerant will ALWAYS migrate to the coldest place it can, running or not.
The last statement you make above regarding the relay worries me.
Do you understand that they are a matched set? The compressor, start relay, start and run capacitors (if used) and the overload itself are all unique to the compressor and its application.
If you haven't already, please show us the exact model of the compressor itself.

[phorvati]

Originally Posted by Coolerking

The refrigerant will ALWAYS migrate to the coldest place it can, running or not.
The last statement you make above regarding the relay worries me.
Do you understand that they are a matched set? The compressor, start relay, start and run capacitors (if used) and the overload itself are all unique to the compressor and its application.
If you haven't already, please show us the exact model of the compressor itself.

Matched in a sense of current ratings start capacitor voltage and capacitance. PTC(positive temp coefficient) is a non linear element and a PITA. Compressor heat should not disable it. Only the heat from its own current passing through(starting current) by then compressor should be spinning. see post 26.
https://www.cruisersforum.com/forums...ml#post3404333

[Richard Kollmann]

Coolerking, I gave up, when the compressor is replaced believing reed valve cracked. The new compressor will surely come with new PTC and capacitors.

[Richard Kollmann]

Originally Posted by Richard Kollmann

Coolerking, I gave up, when the compressor is replaced believing reed valve cracked. The new compressor will surely come with new PTC and capacitors.

Coolerking, Not knowing equalized pressure on both sides of compressor before compressor overload starts, was my problem.

[OzeLouie]

Phorvati, thanks for an interesting thread and information provided! Hope you can now resolve your 'compressor failure to start problem.

To condense the findings:
Problem: Compressor wont start unless a few seconds of gas is purged.

Observations: (Assuming the problem is not a power supply issue!!)
A) High side pressure at 60 to 70 PSIG.
B) Compressor only able pull down to 10" vacuum during test.
C) Once started system runs to refrigerates to cut off temp.
D) No report of compressor noise or sweating once started and running.

What the problem is not:
A) It is definitely not due to a shortage of refrigerant gas. Short of gas allows for easier compressor start up, not harder!!
B) It is definitely not due to a discharge line restriction as once started it runs and refrigerates.
C) It is not flooding refrigerant into compressor via the suction as this would require a lot of liquid refrigerant, a lot of purging to get the reported start relief and there would be signs of cooling / sweating of the compressor sump when started and initial running. It would take many ounces to flood that compressor sump sufficiently to fill compression chamber and lock it up.

Conclusions:
A) The compressor most likely has a damaged discharge valve reed as vacuum test indicated. Suction valve reed is ok as indicated by compressor holding vacuum when off after test. Head gasket is also ok.
B) Head pressure is far too low (Over- condensing) as I reported several times. Needs to be approx 120 PSIG.
C) During a long off cycle high side refrigerant is able to dribble 'backwards' into compressors compression chamber via defective discharge reed to where it condenses into small amount of liquid refrigerant, sufficient to prevent the pistons free movement. (May be less than an ounce!)

Suggestions:
A) Fit digital thermostat with probe imbedded between the near top fins of the air cooled condenser. With high side gauge to observe, set SET (cut in) to cause condenser fan / pump to start at 125PSIG and HYS to cause off at 115PSIG. (This alone may overcome start problem as higher head pressure applies greater closing pressure on the discharge reed.)
B) Ideally replace compressor but the existing may still run for years even with defective discharge reed (Fingers crossed!!!)
C) Having completed above, run system, adjust TEV and top up refrigerant.

[Richard Kollmann]

To condense the findings:
Problem: Compressor wont start unless a few seconds of gas is purged.
(Was gas removed from high side or low side, not defined.)

Observations: (Assuming the problem is not a power supply issue!!)
A) High side pressure at 60 to 70 PSIG.
Good

B) Compressor only able pull down to 10" vacuum during test.

Compressor not run long enough to evacuate complete low side but 10 inches confirms both reed valves Good

C) Once started system runs to refrigerates to cut off temp.
D) No report of compressor noise or sweating once started and running.

Both C and D confirm no problems inside compressor.

What the problem is not:
A) It is definitely not due to a shortage of refrigerant gas. Short of gas allows for easier compressor start up, not harder!!

Correct low on refrigerant has nothing to do with compressor overload on start.

B) It is definitely not due to a discharge line restriction as once started it runs and refrigerates.

Correct no restriction confirmed by test results.


C) It is not flooding refrigerant into compressor via the suction as this would require a lot of liquid refrigerant, a lot of purging to get the reported start relief and there would be signs of cooling / sweating of the compressor sump when started and initial running. It would take many ounces to flood that compressor sump sufficiently to fill compressionchamber and lock it up

Liquid flooding of compressor not confirmed By frost on any area after eutectic evaporator or even suction line or accumulator. This condition would be possible if TXV orifice was excessive, Example ½ ton instead of ¼ ton.


Conclusions:
A) The compressor most likely has a damaged discharge valve reed as vacuum test indicated. Suction valve reed is ok as indicated by compressor holding vacuum when off after test. Head gasket is also ok.
B) Head pressure is far too low (Over- condensing) as I reported several times. Needs to be approx 120 PSIG.
C) During a long off cycle high side refrigerant is able to dribble 'backwards' into compressors compression chamber via defective discharge reed to where it condenses into small amount of liquid refrigerant, sufficient to prevent the pistons free movement. (May be less than an ounce!)

A,B,C assumptions were not proven only theories


Suggestions:
A) Fit digital thermostat with probe imbedded between the near top fins of the air cooled condenser. With high side gauge to observe, set SET (cut in) to cause condenser fan / pump to start at 125PSIG and HYS to cause off at 115PSIG. (This alone may overcome start problem as higher head pressure applies greater closing pressure on the discharge reed.)

A) test is good and will not cause harm to system but it does not solve compressor start up overload problem.

B) Ideally replace compressor but the existing may still run for years even with defective discharge reed (Fingers crossed!!!)

B) If compressor will reach a high pressure in operation then 120 psi confirms reed valves are normal. I would give up the reed valve guess and concentrate on solving electrical starting load and TXV setting.

I have to admit this one of a kind system that's design moved the problem and solution more than once.

[OzeLouie]

[To avoid confusion: (Richards response in red follow up OzeLouie in blue)

To condense the findings:
Problem: Compressor wont start unless a few seconds of gas is purged.
(Was gas removed from high side or low side, not defined.) Read the thread!

Observations: (Assuming the problem is not a power supply issue!!)
A) High side pressure at 60 to 70 PSIG.
Good… Wrong, it is not good. 60-70 with virtually no TD across the condenser is NOT correct. Over condensing.

B) Compressor only able pull down to 10" vacuum during test.

Compressor not run long enough to evacuate complete low side but 10 inches confirms both reed valves
Good…
Wrong, Only achieving a 10” vacuum after 5 to 10 minutes run with suction CLOSED off at compressor indicates faulty discharge valve reed. (Industry recognised procedure used for this test!!!)

C) Once started system runs to refrigerates to cut off temp.
D) No report of compressor noise or sweating once started and running.

Both C and D confirm no problems inside compressor.
Wrong: C & D were listed as observations!!

What the problem is not:
A) It is definitely not due to a shortage of refrigerant gas. Short of gas allows for easier compressor start up, not harder!!

Correct low on refrigerant has nothing to do with compressor overload on start,
Correct. So you agree but why did you promote the low gas issue as a cause?

B) It is definitely not due to a discharge line restriction as once started it runs and refrigerates.

Correct no restriction confirmed by test results.
Correct. So again now you agree but why did you promote the restricted discharge issue, including opening the system to add a service valve, as a cause when it was obvious from the get-go that it had nothing to do with the start failure?

C) It is not flooding refrigerant into compressor via the suction as this would require a lot of liquid refrigerant, a lot of purging to get the reported start relief and there would be signs of cooling / sweating of the compressor sump when started and initial running. It would take many ounces to flood that compressor sump sufficiently to fill compression chamber and lock it up

Liquid flooding of compressor not confirmed By frost on any area after eutectic evaporator or even suction line or accumulator.
Correct: We are on a roll of agreement here RK! Good stuff.
This condition would be possible if TXV orifice was excessive, Example ½ ton instead of ¼ ton. Yes but not the case here as there are no symptoms reported to confirm suction flooding!


Conclusions:
A) The compressor most likely has a damaged discharge valve reed as vacuum test indicated. Suction valve reed is ok as indicated by compressor holding vacuum when off after test. Head gasket is also ok.
B) Head pressure is far too low (Over- condensing) as I reported several times. Needs to be approx 120 PSIG.
C) During a long off cycle high side refrigerant is able to dribble 'backwards' into compressors compression chamber via defective discharge reed to where it condenses into small amount of liquid refrigerant, sufficient to prevent the pistons free movement. (May be less than an ounce!)

A,B,C assumptions were not proven only theories..
Wrong, not theories but the application of fundamental refrigeration system analysis procedures as recognised by qualified industry technicians. These industry factors evolved as a result of applying physics (thermodynamics) to guide the practicing technician / engineer, not guess work!

Suggestions:
A) Fit digital thermostat with probe imbedded between the near top fins of the air cooled condenser. With high side gauge to observe, set SET (cut in) to cause condenser fan / pump to start at 125PSIG and HYS to cause off at 115PSIG. (This alone may overcome start problem as higher head pressure applies greater closing pressure on the discharge reed.)

A) test is good and will not cause harm to system but it does not solve compressor start up overload problem. Somewhat wrong. I did not say it would solve the fail to start problem but may help. Certainly over condensing of this system is a problem and you seem to be coming around to now agree with that.. Good.

B) Ideally replace compressor but the existing may still run for years even with defective discharge reed (Fingers crossed!!!)

B) If compressor will reach a high pressure in operation then 120 psi confirms reed valves are normal. [COLAgree / Wrong! OR="red"]Wrong.[/COLOR] With cracked or damaged valve as confirmed with suction test, a compressor can still push reasonable head pressure but varies depending on degree of reed damage and this one is minor.
I would give up the reed valve guess and concentrate on solving electrical starting load and TXV setting. I agree the power supply, relay capacitor etc may be the cause or contributing to this problem but it has nothing to do with the TXV setting as suction flooding is not happening (See earlier comment)
BTW the ‘read valve thing is offered as a result of industry recognised procedure, hands on experiences and training. It is not a 'guess' as you sarcastically suggest or something gleaned off the web or others, and again if you can explain a better test then let’s have it.

Also and again for the third time, please provide a link to the Technautics web site you quoted as confirming support for your statement regards the failed compressor suction.

I have to admit this one of a kind system that's design moved the problem and solution more than once. Agree. But hopefully interesting for readers as many concepts and procedures are explained.

[Richard Kollmann]

Louie, we now, I think have all the facts of many possibilities seeing views of long threads choices to re-commission this refrigeration system. There will be no winners or losers once these problems are corrected.

The interesting thing about these threads is the number of real experts in this business who read and enjoy using info to improve marketing skills