Ugh, DUMB ASS needs help with 407C?!

[mrpotts]

Hi All,

I am the solo marine engineer on a private yacht. We have four Climma, 407C, units for air conditioning which chill water running through the ship. We have had three out of four fail in the last month, two condenser internal seawater pipes and one compressor bushing failure. I have a new compressor and I am repairing a condenser. Basic question is, how do I commission a new system?

I know this is an open-ended question, but unfortunately I know only the basics of refrigeration. It is my weak spot. At the moment I am flushing the evap & TXV with alcohol. I will get the condenser tomorrow and button up the system with a new dryer.

My thinking then is to re-flush the system with alcohol again, the evap, TXV, new compressor, rebuilt condenser. Once this flushes for awhile (how long??) I will then low-charge the system with nitrogen while I solder in the new dryer to seal the system from the atmosphere. Then I will charge the system for awhile (how long??) to allow the nitrogen to 'absorb' moisture from the atmospheric air left in the system while I am intermittently (or constant??) pulling vacuum. After this, I will add oil (how much, halfway to sight glass?) and then charge the system with 407C (50-70PSI=Low side, 150-250PSI=High side).

Does this sound okay, or am I missing the mark here? Thanks for any help. I am relaying solely on this forum for advice as there is no one here to ask questions.

Thanks,
Phil

[nike123]

Hi All,

I am the solo marine engineer on a private yacht. We have four Climma, 407C, units for air conditioning which chill water running through the ship. We have had three out of four fail in the last month, two condenser internal seawater pipes and one compressor bushing failure. I have a new compressor and I am repairing a condenser. Basic question is, how do I commission a new system?

I know this is an open-ended question, but unfortunately I know only the basics of refrigeration. It is my weak spot. At the moment I am flushing the evap & TXV with alcohol. I will get the condenser tomorrow and button up the system with a new dryer.

My thinking then is to re-flush the system with alcohol again, the evap, TXV, new compressor, rebuilt condenser. Once this flushes for awhile (how long??) I will then low-charge the system with nitrogen while I solder in the new dryer to seal the system from the atmosphere.

Does the see entered in to the system?

You need to allow nitrogen to flow thru place were you welding.That mean you feed nitrogen on one place and release on other, and welding spot is in between. Nitrogen you feed thru flow regulated reducing valve, (like for argon or CO2 welding) Adjust flow at minimum, just to feel gas movement on finger when you moisture your finger and put him at gas outlet.
Before welding, flush with nitrogen for some time to extract oxygen from pipes.


Then I will charge the system for awhile (how long??) to allow the nitrogen to 'absorb' moisture from the atmospheric air left in the system while I am intermittently (or constant??) pulling vacuum.After welding you need to perform leak test! Pressurize system gradually (5 bar, 10 bar, 15 bar) until you reach maximum allowed system pressure. Then if pressure holds after 1 hr. note pressure and ambient temperature (ambient of system) and come back after 24 hours and check pressure and ambient temperature change. If it is OK, then your system is tight and you could release nitrogen and switch to evacuation job.
Before evacuation, you should add oil. Don't keep can of oil opened more then 10 min., and don't use oil from already opened cans, no matter how tight are they sealed.
You could search this forum about proper evacuation. Most important is good vacuum pump capable to pull vacuum below 100 microns and micrometer vacuum gauge to be able to see what you are doing.
http://www.refrigeration-engineer.com/forums/showthread.php?t=5528&highlight=vacuum+procedure
http://www.refrigeration-engineer.com/forums/showthread.php?p=89159&highlight=leak#post89159


After this, I will add oil (how much, halfway to sight glass?) and then charge the system with 407C (50-70PSI=Low side, 150-250PSI=High side).You should not charge system by pressure. System is charged by weight, sight glass, superheat and subcooling. Pressures are dependent at air (water) temperature and quantity and they need to bee converted to saturation temperatures.

Read thread "pressures are meaningless".
If you are going to do this by your own, I suggest supervision from someone trained for this job.

[mrpotts]

Hi Nike,

The system I am putting back together is the one with the faulty compressor, so no seawater has entered the system. It has entered on the other two units, one which is missing components (compressor and condenser) and the other which I have gassed up and pressurized. It is not operating correcting though as the low pressure reading is fluctuating and I am suspecting the TXV may be contaminated and not operating correctly. That unit is a story for another day :>

I hear you regarding the supervision and this was my suggestion to the management. However I am in Hong Kong and have regular phone and shop access to the refrigeration 'Guru' of Hong Kong in Aberdeen. Earlier on, after discovery of seawater contamination on the other units, he suggested I use nitrogen before charging to 'clean' the system. I asked if I should flush with hot water first to clean out the salt water and he said this would be a good idea. I did this, then used the nitrogen, then charged the system to some success and this is the system I referred to just above. It was only after reading some posts here that I realized alcohol would be better. Point being, there is no one for me to rely on. It is not a great situation, but it's the one I'm in. Oh, and recovery procedures here in Hong Kong, non-existent, unless you consider the atmosphere a recovery vessel.

Cheers,
Phil

[nike123]

Hi Nike,

The system I am putting back together is the one with the faulty compressor, so no seawater has entered the system. It has entered on the other two units, one which is missing components (compressor and condenser) and the other which I have gassed up and pressurized. It is not operating correcting though as the low pressure reading is fluctuating and I am suspecting the TXV may be contaminated and not operating correctly. That unit is a story for another day :>

I hear you regarding the supervision and this was my suggestion to the management. However I am in Hong Kong and have regular phone and shop access to the refrigeration 'Guru' of Hong Kong in Aberdeen. Earlier on, after discovery of seawater contamination on the other units, he suggested I use nitrogen before charging to 'clean' the system. I asked if I should flush with hot water first to clean out the salt water and he said this would be a good idea. I did this, then used the nitrogen, then charged the system to some success and this is the system I referred to just above. It was only after reading some posts here that I realized alcohol would be better. Point being, there is no one for me to rely on. It is not a great situation, but it's the one I'm in. Oh, and recovery procedures here in Hong Kong, non-existent, unless you consider the atmosphere a recovery vessel.

Cheers,
Phil

Could you describe your procedure and equipment for flushing with alcohol?

[mrpotts]

Sure, I'm doing it right now and breaking away from the pumping to come up here. At the moment, I am only flushing the evap and TXV. The dryer is removed. I have an air diaphragm pump (Wilden) taking suction from a bucket of isopropyl alcohol and discharging into the refrigerant inlet of the evaporator. Another hose is connected to the evap discharge and 'drops' back into the bucket. The first 10 liters I put in another bucket to 'attempt' to keep the oil out of the flush, as much as possible. Does this seem an effective procedure? Pretty caveman-ish huh?

Phil

[taz24]

2 things come to mind straight away.

The first is do you evacuate the system after the nytrogen pressure test?
You must. You must remove all traces of air and other gases from the system. The evacuation (vac) will also remove any remaining moisture and alcohol.

The second point is the recharge with refrigerant.
What are you using to correctly charge the system with refrigerant?
Is there a sight glass in the liquid line just before the TEV (TXV). When charged with refrigerant the sight glass should be clear.

taz.

[nike123]

Sure, I'm doing it right now and breaking away from the pumping to come up here. At the moment, I am only flushing the evap and TXV. The dryer is removed. I have an air diaphragm pump (Wilden) taking suction from a bucket of isopropyl alcohol and discharging into the refrigerant inlet of the evaporator. Another hose is connected to the evap discharge and 'drops' back into the bucket. The first 10 liters I put in another bucket to 'attempt' to keep the oil out of the flush, as much as possible. Does this seem an effective procedure? Pretty caveman-ish huh?

Phil

You should remove TXV and flush evaporator in such way that is filled with flushing agent entirely. Purge air and circulate fluid some time and than change liquid and repeat circulation. Do this few times. Ensure that is no air in evaporator.
Is it plate type evaporator?
Then flush TXV separately in both directions, and if possible disassemble him and flush and then blow nitrogen at him.

[mrpotts]

Taz,

The system will be evacuated after nitrogen leak test, using a vacuum pump. Regarding the charge, I did the last system, mentioned above, incorrectly on pressure gauges. At the moment, I do not know how to charge a system correctly. Weigh the cylinder before and after adding the refrigerant? I do not know what the system design refrigerant charge weight is. It is a 96000 BTU unit. The sight glass is after the dryer, before the evaporator.

Nike,
Removing the TXV does not seem to be an option. I tried yesterday with Mapp gas and could not liquify the solder after 30 minutes of heat. I do not have Ox/Ace onboard. I do not know why the solder wouldn't break, I am guessing the Mapp gas could not get up to the required temperature. It works fine on the soldering for the dryer. Another reason to not remove the TXV now is time. I need to get the system up and running for use and I am reluctant to disassemble any more components. A hard lesson for me in marine engineering is sometimes 80% complete is better then an inoperative system.

I don't know the type of evaporator. It is wrapped up and bolted down from the inside. To disassemble I need to open the chill water system and stop the last remaining AC unit which will heat up the boat quickly. I will see about reversing flush flow direction.

Cheers,
Phil

[SteinarN]

Removing the TXV does not seem to be an option. I tried yesterday with Mapp gas and could not liquify the solder after 30 minutes of heat.
Phil

Ouch...

The TEV head doesn't stand high temperatures. Anything over maybe 200*C will probably kill it. What temperature do you think you had at the head of the valve?

[mrpotts]

Oow, well, the flame was not directly on the valve head (flat plate?) but on the soldered joint just above the valve. Never the less, I am sure the temperature was up there as a quick search shows app gas "is used for welding due to its high combustion temperature of 2927 °C (5301 °F) in oxygen." However, I used a heat gun on the bulb of the TXV today and noticed a difference in flow while pumping. Is there another way to determine a faulty TXV? God, the news seems to just keep getting worse!

Phil

[SteinarN]

The valve should be fully open when it is subjected to atmospheric pressure and normal room temperature. Otherwise it is defect. What make is the valve? Is it possible to remove and replace the powerhead (flat plate) only?

[nike123]

Nike,
Removing the TXV does not seem to be an option. I tried yesterday with Mapp gas and could not liquify the solder after 30 minutes of heat. I do not have Ox/Ace onboard. I do not know why the solder wouldn't break, I am guessing the Mapp gas could not get up to the required temperature. It works fine on the soldering for the dryer. Another reason to not remove the TXV now is time. I need to get the system up and running for use and I am reluctant to disassemble any more components. A hard lesson for me in marine engineering is sometimes 80% complete is better then an inoperative system.

Brazing/unbrazing on HVAC system should be done with Mapp or acetylene wit adding oxygene because you need to heat brazing surface to melting point of filler rod. Depending on filler rod that could be from 500°C up. That TXV is probably brazed with low silver content brazing rod or copper-phosphor rod (700-800°C melting tem.) which have melting temperatures above what you could reach with that torch . The filter dryer is probably brazed with high content silver alloy (650°C melting) rod and therefore is un-brazed with your torch. Also, it is important even distribution on heat at brazed surface.

When un-brazing you need to protect heat sensitive parts with wet rag. Also you need to equally distribute heat at hole brazed surface and that could be tricky.
When you have major system break-down (as you experiencing) you should change TEV with new one, along with filter drier and sight glass.
In refrigeration you do not un-braze unless it is absolutely necessary. Instead you cut pipe at appropriate place and expand pipe or fit fitting to accommodate new part.

You really need proper tools and supervisor, otherwise, you could make much more damage than it is now.

I hope that if you explain this to captain that he will organize proper tools and supervision.

[Gary]

In order to avoid confusion, let's discuss one system at a time... and one procedure at a time.

Describe the system you are working on and explain why you are flushing it.

[mrpotts]

In order to avoid confusion, let's discuss one system at a time... and one procedure at a time.

Describe the system you are working on and explain why you are flushing it.


Hi,

I understood the request. I am working on system No. 2 (out of 4) which has a brand new compressor (just received from the States), no condenser, and the original evaporator, TXV, and sight glass at the moment. I am flushing the system to remove the previous oil and any metal contaminants from the failed internal compressor components.

I have found out tonight the condenser, after opening, is not repairable. However, after contacting a Stateside source, I may have 3 new condensers and 1 compressor coming.

Cheers,
Phil

[Gary]

It is best to flush coils from the bottom up. this fills every little nook and cranny with the liquid flushing agent.

[nike123]

Hi,

I understood the request. I am working on system No. 2 (out of 4) which has a brand new compressor (just received from the States), no condenser, and the original evaporator, TXV, and sight glass at the moment.


If I correctly understood, you are flushing system on which see has entered?

[mrpotts]

If I correctly understood, you are flushing system on which see has entered?

This unit I am currently working on has not had seawater enter into the system.

[nike123]

This unit I am currently working on has not had seawater enter into the system.
Does compressor motor has burn out, or it was mechanical damage?
You should read this article:
http://www.hvacrinfo.com/cope_ae_bulletins/TAE1105.PDF

[mrpotts]

Hi All,
I was away from PC all day yesterday. Here is an update. We got word this morning that our condensers are not available as they were "experimental.". Cap'n has had enough with Climma and ordered 4 new MarineAir units which will take appx. 3 months for delivery/installation.

In the meantime, we are drydocking the boat this Monday for 3 weeks. I need to get at least one more unit up and running and I will focus on #1 which has the new compressor. A recap:

Unit#1: Working on this unit
Unit#2: Flushed, pressurized, & cooling but alarming-Inoperative
Unit#3: Inoperative-Only Evap here
Unit#4: Operating Normally

Unit #1:
I have removed the TXV & sight glass today. I have a new TXV, Sight Glass, Dryer, & compressor for this unit. I am currently flushing the evap alone for the 2nd time with alcohol. I am going to remove the Condenser from Unit#2 & install it on Unit#1. Then I will flush for the last time the New Sight Glass, Evap, & Condenser. Any preference over flushing with Alcohol or Acetone? After flush I will install new TXV, pipe up the new compressor & then use a nitrogen flow to remove moisture, pressurize to leak test. Once satisfactory, it's vacuuming, adding oil, then refrigerant. A couple questions if I may.

Does this procedure seem to be on target or am I missing something?

Do I need to adjust the new TXV? How to I adjust correctly?

How long & how do I determine when I have pulled enough vacuum?

How do I know how much oil to add?

I'm sure there will be more questions but for the moment my motivation is to get the system back together to the point I can get Nitrogen in it.

Thanks for all the advice. You all have been a great help. My Captain has this link & may be reading it too.

Cheers all,
Phil

[Gary]

Unit#2: Flushed, pressurized, & cooling but alarming-Inoperative

I am going to remove the Condenser from Unit#2 & install it on Unit#1.

Wouldn't it make more sense to figure out why unit #2 is "alarming-inoperative"?

[mrpotts]

Wouldn't it make more sense to figure out why unit #2 is "alarming-inoperative"?


I can understand the wisdom of what you are saying and why you are asking the question. My reasoning is this; The original failure was a condenser salt water failure. I flushed the system with hot water, not alcohol or acetone. I used nitrogen but it was my first time using, I didn't pressure test system, I didn't replace the dryer, sight glass, or TXV. I suspect there may be compressor bushing damage this is only a hunch. For these reasons, my experience level, and the need-it-now time factor, I am going to pull the condenser and install it in Unit #1 with mostly new components.

I am sure a better reefer engineer could do better, but this is the hand I have at the moment.

Phil

[Gary]

What is #2 doing that it shouldn't be doing... or not doing that it should be doing?

[mrpotts]

It is chilling but bringing the chill water temperature down very slowly. After an amount of time, the control system takes it out of service due to an alarm condition. I have not looked into what the alarm is as the system isn't that specific. Anyway, I don't want to dwell on Unit#2 because it now has no charge and I will pull the condenser in the morning. There are to many variables with this system that could be faulty.

Phil

[Gary]

It is chilling but bringing the chill water temperature down very slowly. After an amount of time, the control system takes it out of service due to an alarm condition. I have not looked into what the alarm is as the system isn't that specific. Anyway, I don't want to dwell on Unit#2 because it now has no charge and I will pull the condenser in the morning. There are to many variables with this system that could be faulty.

Phil

Replace the oil, replace the drier, evacuate and charge. Not that many variables.

I almost forgot... clean the inlet screen on the TXV.