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Post by elec573 on Nov 1, 2018 3:03:21 GMT
Very nice work you make it look easy!
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Post by turbokinetic on Nov 1, 2018 4:50:56 GMT
Very nice work you make it look easy! Thanks! It's not hard. Nothing I did was hard at all. Just time consuming and a bit tedious. Cleaning, inspecting, re-sealing, painting....
So; for the problem I had yesterday with the refrigerant backflooding.... The return line from the evaporator was frosted up and sweating all the way back to the compressor. That means the float isn't doing its job. It isn't slowing down the flow of liquid refrigerant when it's supposed to. It is supposed to slow down the liquid entering the evaporator when the level of liquid gets too high. It is supposed to regulate the level so that liquid doesn't reach the suction line and cause the backflooding problem we saw yesterday.
The float was originally calibrated to float at the correct position, based on the liquid density of SO2. The R152A is much lighter weight than SO2, therefore the float would not ride at the same level. I have added a spring to the float to compensate for the density difference, to a certain degree. The spring was tried on my 1931 Frigidaire and worked well. I installed the same spring on this unit, however it did not work. I got another used float from a newer unit, and then compared it to the float from this evaporator. The float from this one was smaller, and non-adjustable. I hadn't realized it was smaller. That would make the spring requirement different.
So, to save time and put my previous testing to use; I swapped the float out for the adjustable one. The spring is set so that the float "just barely" falls down to the open position, by gravity. The position adjustment is adjusted so that the float will "just barely" rest on the bottom of the evaporator header when the cap is installed. This is notes from my 1931 Frigidaire repairs.
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So, after putting the evaporator back in, this was the result! Success!
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I couldn't resist setting these up side by side. Left is my 1931 Frigidaire, with twin cylinder compressor and capacitor start motor. The one on the right is Travis's one, with the single cylinder compressor and repulsion-start motor.
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Today I made some adjustments to the control, so that it will cycle at an acceptable temperature with the new refrigerant. This just entails installing a different spring. I still have to remove the left door trim and change the cold control cables, then it'll be ready to go home!
Some video from the day's testing!
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Post by Travis on Nov 1, 2018 4:59:48 GMT
I can find you some ladder chain.
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Post by turbokinetic on Nov 1, 2018 5:06:21 GMT
I can find you some ladder chain. Excellent. They may have it at the Lawrence Hardware about 1 mile from my home. Before paying postage, let me check there.  |
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Post by Travis on Nov 1, 2018 5:09:30 GMT
If not, let me know the approximate size of the links.
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Post by elec573 on Nov 2, 2018 5:19:55 GMT
Those are both beautiful refrigerators! Very nice work I’m drooling! It would be interesting to see a comparison between the monitor tops as far as cooling capacity,power usage
and price at that time.
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Post by birkie on Nov 2, 2018 12:46:16 GMT
Those are both beautiful refrigerators! Very nice work I’m drooling! It would be interesting to see a comparison between the monitor tops as far as cooling capacity,power usage and price at that time. I was thinking the same thing just before I read this |
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Post by birkie on Nov 2, 2018 13:09:53 GMT
Today I made some adjustments to the control, so that it will cycle at an acceptable temperature with the new refrigerant. This just entails installing a different spring. I still have to remove the left door trim and change the cold control cables, then it'll be ready to go home! Excellent! Once it stabilizes, I'd be curious to see the on-off times. |
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Post by turbokinetic on Nov 2, 2018 14:24:17 GMT
Those are both beautiful refrigerators! Very nice work I’m drooling! It would be interesting to see a comparison between the monitor tops as far as cooling capacity,power usage and price at that time.
Thanks! They are out there. If you're diligent and somewhat lucky you'll see one appear for sale. These wood cabinet ones have to be kept indoors or they deteriorate. It's important to find one which has not been "put out to pasture" for decades.
I don't really know how to measure cooling power without very costly instrumentation and modifications to the unit. Power usage is easy enough to measure, of course. Travis's Frigidaire cabinet is all original including the door gasket and insulation. Mine has been re-insulated and has a new gasket. I'm sure that will have an effect.
Today I made some adjustments to the control, so that it will cycle at an acceptable temperature with the new refrigerant. This just entails installing a different spring. I still have to remove the left door trim and change the cold control cables, then it'll be ready to go home! Excellent! Once it stabilizes, I'd be curious to see the on-off times.
That's an interesting one. The control is very finely adjustable. There is a setting specifically for the range between cut-in and cut-out. Since this is measuring pressure on the low-side of the system (not actual temperature) there are some factors at play we don't normally see when it comes to cycle times. One significant factor is the boiling of the refrigerant. There is some effect going on with the large volume of low pressure liquid. It pops and thumps when it starts to boil. The pressure will slowly rise during the off-cycle. Then, there will be a "bump" or "thump" or series of small ones - and the pressure will rise suddenly. This usually happens right after the compressor starts up, when the pressure is falling in the evaporator. It seems like the liquid becomes "superheated" (relative the the temperature/pressure chart) and then finally starts boiling with a flash.
We hear small pops from the thinner cross-section evaporators all the time, so it seems this is normal, but just sounds different from the very large evaporator.
Another interesting quirk I have noticed is the "two types of cyles" they have. Once the cabinet temperature is pulled down, the unit will have very short ON cycles, two or three times, then it will have one long ON cycle, and then a long OFF cycle. Again, the evaporator pressure is causing this. Personally, I don't have a problem with this. But, it is probably one of the reasons they went to an actual temperature sensing control. The actual refrigeration system has so many dynamics at play which don't affect the performance of the unit, but make it hard to predict the temperature based on the pressure.
So, the short answer is, the on and off times are adjustable and there is no factory setpoint to get a reference against.
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