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Post by cablehack on Dec 19, 2014 2:09:42 GMT
Wow guenea pig still runs. Duty cycle wasn't to great, so now I'm refocusing my attention on cap tube cal. Yuck. I think I went to short with the 031 cap. I used my pinch off tool and started Givin it a little pinch. Cycle times immediatly changed for the better. Duty cycle now at 33%. So I'm gonna remove cap tube and start over. Maybe a whole roll of 031, and go from there. I'm shooting for a duty cycle in the low 20% range, then I'll be satisfied. With the lower power consumption of R123 and a duty of let's say 25%. That will make it more efficient than my MF CA, and almost into the CK neighborhood. Presumably you can work on the machine with it charged and purge after as with MF. Does the purging work the same way? Anything to smell when it's purged or do you just go by condenser and float chamber temp to know when to stop? 33% duty cycle is not a bad starting point - that would be within spec if it was a DR. If there was oil migration, how long would you expect it to take to show up? |
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Post by blackhorse on Dec 19, 2014 4:47:16 GMT
You might think slightly less so if you had had them explode in the refrigerator. >.< Note: less sugary drinks explode easier than sugared soda. One of life's more "What the .... " moments when you open the door and there's foam frozen to every inside surface. Now I have an alarm-- The loud bitching noise whenever there are ice crystals in the lettuce.........  An exploded soda can is how I set my thermostat. I put in a soda and over several days turn down temp a degree at a time. When can freezes and explodes you simply set thermostat one degree warmer and you got it right :-))))). Love em KOLD I have enough trouble justifying "old stuff" in the house. Any aberrant behavior and we start getting comments about having to buy some foamed-in-place Chinese POS as replacement. And yes, straight up looks best. There's a symmetry.......... |
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Post by jhigdon2 on Dec 19, 2014 6:36:07 GMT
Wow guenea pig still runs. Duty cycle wasn't to great, so now I'm refocusing my attention on cap tube cal. Yuck. I think I went to short with the 031 cap. I used my pinch off tool and started Givin it a little pinch. Cycle times immediatly changed for the better. Duty cycle now at 33%. So I'm gonna remove cap tube and start over. Maybe a whole roll of 031, and go from there. I'm shooting for a duty cycle in the low 20% range, then I'll be satisfied. With the lower power consumption of R123 and a duty of let's say 25%. That will make it more efficient than my MF CA, and almost into the CK neighborhood. Presumably you can work on the machine with it charged and purge after as with MF. Does the purging work the same way? Anything to smell when it's purged or do you just go by condenser and float chamber temp to know when to stop? 33% duty cycle is not a bad starting point - that would be within spec if it was a DR. If there was oil migration, how long would you expect it to take to show up? |
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Post by jhigdon2 on Dec 19, 2014 6:43:03 GMT
The purging procedure is the same and I've already changed the capillary once with a full charge in the unit. It virtually behaves the same as MF, except this stuff is not flammable. I will start out with a long .031 tube and just keep bobbing it off until it behaves itself and has nice low duty cycle. And yet still be able to ha handle a load, such as making ice cubes without floundering. This R123 has a similar smell as Mf, just not quite as strong.
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Post by jhigdon2 on Dec 19, 2014 6:48:19 GMT
Oil migration is anybody guess. So far I still hear plenty of oil activity going on in sump. I'm pretty sure oil.is leaving, but I have a feeling it's also coming back. I think running it for a few weeks will shed some light on any oil migration issues.
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Post by cablehack on Dec 19, 2014 11:32:02 GMT
Oil migration is anybody guess. So far I still hear plenty of oil activity going on in sump. I'm pretty sure oil.is leaving, but I have a feeling it's also coming back. I think running it for a few weeks will shed some light on any oil migration issues. If my CA-1 experience is anything to go by, there would have to be oil leaving the compressor. There was a film of oil all over the side and bottom of the evaporator, and some had run down to the bottom of the cabinet. I don't think the owner had run it as long as he said with the tube broken, because there was enough MF left in the system to give a good spray once the float valve lifted. |
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Post by jhigdon2 on Dec 26, 2014 18:41:41 GMT
The guenea pig is still running! It's been an interesting journey however. After several cap tube adjustments, I finally settled on 120" of .031.
At the same time I was doing the dance with different heaters. I tried a 18 watt, a 25 watt, and a 10 watt heater. None of which made a bit of difference in performance. Then I finally tried "no heater". This is where it got even more interesting. With no heat, it runs great. Even though this CA is a tired old unit with a weak start winding, broken check valve, and a pump that is only capable of pulling about 26in. Vacuum, (I installed external check valve) duty cycle is 38%, 140 watts at start up and 121 watts at at shutdown at 6 deg evap. Total kw in 24 hr period is exactly 1.0 kw.
Not to shabby. The R123 and the absence of a heater makes it darn near as efficient as a CK series machine. And it handily makes ice cubes without even straining!
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Post by ChrisJ on Dec 26, 2014 20:59:48 GMT
What's the ambient temp John?
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Post by jhigdon2 on Dec 26, 2014 21:43:05 GMT
Ambient is 70 deg. Box temp is 36. Evap temp on: 20 deg off @ 6 deg.
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Post by jhigdon2 on Dec 28, 2014 1:26:35 GMT
The CA machine ran beautifully with no oil heat for about 26 hours. Then the tell tail signs of evap starvation began to show. Frost line was dropping and on/off times began to degrade. So know I know the R123 does need some heat. The good thing about it is that it don't need much. I now have a 10 watt heater in the unit and it has recovered nicely and seems to run real good again.
Now that I've got the oil heat hurdle nailed down, and cap tube length pretty much nailed, I'm gonna revisit the task of optimizing the refrigerant charge one more time.
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Post by allan on Dec 28, 2014 6:14:12 GMT
The CA machine ran beautifully with no oil heat for about 26 hours. Then the tell tail signs of evap starvation began to show. Frost line was dropping and on/off times began to degrade. So know I know the R123 does need some heat. The good thing about it is that it don't need much. I now have a 10 watt heater in the unit and it has recovered nicely and seems to run real good again. Now that I've got the oil heat hurdle nailed down, and cap tube length pretty much nailed, I'm gonna revisit the task of optimizing the refrigerant charge one more time. John the suspense is getting to me! We need some pics of that evap and its frost line. |
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Post by jhigdon2 on Dec 29, 2014 4:01:09 GMT
I'll get some pics as soon as I can quit fooling around with it. I keep on shutting it down to tinker with it and everthing melts. I however am learning more all the time. I am now running it hard to find out how it's going to behave in hot weather, high heat load. So far I'm not impressed. The 10 watt heater seems to be a little small. Frost Line is slowly dropping. I also have noticed that there is a definite evap temp limit that this machine won't go below. (5deg) no matter how long it runs. I think this is attributed to the poor condition of this compressor. Even when this unit still had the methyl formate in it, it was a poor performer at best. Even when I converted it to a cap tube. By looking at the temp curve of R123 I would guess that if this unit were in better condition, it would easily have enough capacity to pull evap down to 10-15 deg below zero with no problem. But it's a good guenea pig. Willing to give it's life for science. Lol
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Post by jhigdon2 on Jan 2, 2015 22:43:17 GMT
The guenea pig has been running for a month now. Finally optimized the charge, and crankcase heat, and hopefully cap tube sizing. One of the items that was throwing me a curveball was optimizing refrigerant charge. It ended up taking a bit more R123 than even the nameplate charge amount. I kept on ending up with low frost lines and short off times. The R123 is mineral oil miscable, so I have to assume that when charging one of these, that the oil is gonna mop up some of the charge. The unit is running pretty good, considering it's a little worn. On/off times 2:30 on 12 off. So I'm gonna leave it alone and see how it goes. I am impressed with the R123 and really don't forsee any problems with oil migration as of now. It still sounds like there is plenty of oil in the sump by listening to the bubbling noises during off cycle. Attachments:
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Post by cablehack on Jan 3, 2015 21:39:38 GMT
I'm most impressed with your results. I always thought R123 would work, but the question was what the practicalities were. I didn't foresee the cap tube difference, but it makes sense. The duty cycle you're getting is the same as my CA-1 in summer, so it would seem everything is optimised.
What would be interesting is to do a comparison test on a machine with a working float valve.
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Post by ChrisJ on Jan 3, 2015 22:35:33 GMT
What about the worn compressor though?
Won't a stronger compressor cause issues with the same cap tube? Similar to cablehack's 50Hz vs 60Hz?
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