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Post by ckfan on Oct 29, 2018 14:09:45 GMT
This is the other project I started in the basement. If you noticed the thread on the CA form B I started, this unit came from the same friend of Travis. It is a late model type D DR. It is in pretty rough shape but it does show signs of life. Last week I stuck a heater in it and let it warm up. Then I crossed my fingers and turned it on. It was slow to start as if it had been sitting for decades. It did turn on though and didn’t trip the overload. It started trying to cool but then did what most neglected DRs do and started pulling into a vacuum as the float valve wasn’t opening. I gave it a good whack with a wrench and it immediately opened and the watts went to normal. Then it started dropping and rattling again as the float wouldn’t open. Even with repeated whacks and heat gun treatment on the liquid line, it wouldn’t cooperate.
Here’s the weird part though. If you shut it off and wait for it to stabilize and then turn it back on... it does the same exact thing every time. Sometimes it will even make the float open on its own, once. Sometimes you have to hit it. Regardless, it will not open the float once it’s been running and once it’s been opened already in that run cycle. The strange thing is how repeatable this is. This leads me to believe there is something wrong with the linkage that is preventing it from opening on its own. It’s not plugged up because it will even frost the evaporator at first when it opens up. Over time though it will just pull deep into a vacuum, rattle, watts drop, and the frost goes away.
So I wanted to pick everyone’s brains and see what those who have lots of experience with DRs have to say. To me it’s so strange that this problem is so repeatable.
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Post by birkie on Oct 29, 2018 14:44:39 GMT
Regardless, it will not open the float once it’s been running and once it’s been opened already in that run cycle. The strange thing is how repeatable this is. This leads me to believe there is something wrong with the linkage that is preventing it from opening on its own. It’s not plugged up because it will even frost the evaporator at first when it opens up. Over time though it will just pull deep into a vacuum, rattle, watts drop, and the frost goes away Could it be low on refrigerant? When you started it up the first time, did you get a vigorous boil in the evaporator, and frost line that suggests the evaporator was entirely full? A combination of low refrigerant and a sticky float could possibly cause similar symptoms. One definitive way to check is to shut off the machine when it is in vacuum, then heat up a spot on the lower half condenser coils with a heat gun. If it has a full charge, and has drawn all refrigerant out of the evaporators, then the liquid will back up the condenser quite a ways. Heating it up will make obvious boiling noises if it is full of liquid. That would confirm that is has significant charge, and the float isn't letting anything through. The thing about a worn linkage is that I can't quite understand why it would always work the first time, but no other. I would expect the float not to open at all some times, and/or to open for a period of time, then stop.
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Post by turbokinetic on Oct 29, 2018 15:03:48 GMT
I was about to comment on the charge level based on your observation; but see that Aaron already fully explained that point!
Have you ever smelled any SO2 around it? Is there any oil around the service port where someone could have monkeyed with it in the past?
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Post by Travis on Oct 29, 2018 18:29:20 GMT
It does sound like it's low on so2. I guess it's time to lose the rest, check for leaks and charge with 124.
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Post by ckfan on Oct 29, 2018 19:47:18 GMT
That’s a good idea guys. I hadn’t thought of that. I’m not ready to condem the charge just yet though. I’m wondering if the float halfway works when the pressure against it is lower but won’t work when the pressure rises after the machine has been on for a few minutes. There are no signs of leaks and I did crack the purge screw already. Very stinky. The evaporator did fully frost. Quite well actually. I’ll try to heat the condenser and see what that reveals. That’s a good idea. I wonder how far up I should go to indicate a full charge?
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Post by csulaguy on Oct 30, 2018 2:25:36 GMT
I'm jealous - I'd love a D2, but the only one I've seen is out of my price range (unless they negotiate). I actually noticed the same on my recently acquired DR. Wasn't getting super cold. I don't know what I did, but I heard a thunk, probably from the float, and things worked great after that!
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Post by birkie on Oct 30, 2018 3:41:00 GMT
That’s a good idea guys. I hadn’t thought of that. I’m not ready to condem the charge just yet though. I’m wondering if the float halfway works when the pressure against it is lower but won’t work when the pressure rises after the machine has been on for a few minutes. There are no signs of leaks and I did crack the purge screw already. Very stinky. The evaporator did fully frost. Quite well actually. I’ll try to heat the condenser and see what that reveals. That’s a good idea. I wonder how far up I should go to indicate a full charge? I don't think pressure would do anything in and of itself to interfere with the float operation, unless the float was deforming. Think of it this way - the floats work fine on R134a, which is substantially higher pressure than SO2. The DR manual mentions the rare possibility of non-condensable gases "restricting the float operation", but I don't really know what mechanism they'd be referring to. But I hope that isn't the issue with your machine! Anyway, as far as checking the condenser. I did some math. A full 5¾ lb charge is about 116 cubic inches of liquid SO2. The float chamber plus the coils on a D2 looks to hold under 104 cubic inches. So if it sucked the evaporator dry, the entire condenser coil would be full of refrigerant, and some refrigerant would be in the sump. So really, you could point a heat gun almost anywhere on the condenser and listen for boiling. But if low refrigerant is causing the problem, then it'd probably barely fill the float chamber halfway (and none would be in the coils). Another data point for comparison - at approx 171 BTU/lb latent heat for SO2, it'd take 983 BTUs to boil off a full charge in the evaporator. Using the rated capacity of the machine (440 BTU/hr) as very rough estimate, it would take a little over two hours to empty the evaporator, if it was continuously running. Cycling, probably like 4-6 hours. If I recall correctly, my DR1 (with the stuck/plugged float that I had been unable to free by heat and tapping) took ~4 hours of cycling before it reached a vacuum. I got a little over 3.5 lbs of SO2 out of that one, close to a full charge.
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Post by ckfan on Oct 30, 2018 13:55:09 GMT
Very good points Birkie. I bet the evaporator wasn’t sucked completely dry since I had only run it for 10 minutes or so. It was probably just starved of refrigerant and that’s why it felt cool but not cold.
I did the test last night. I let it run for about 10 minutes. At first it acted like it would cooperate, as it does. But to my surprise the watts didn’t start dropping immediately after the first audible opening. Instead they stayed steady for about 2 minutes. I was very happy with this and thought it might start to behave as I could hear the float letting refrigerant by at a very constant rate. Then it shut closed again. It started to rattle and the watts dropped. After about 8 minutes of that I decided to shut it down and break out the heat gun. I heated the bottom half of the evaporator in one specific area. As soon as I turned off the gun I could hear a faint boiling. At first I couldn’t hear it but as my ear adjusted it was clearly boiling. Just not the usual violent boil in the evaporator that I’m used to.
This is the cool part though. I carefully touched the coil and to my surprise it was room temperature. This baffled me at first but then I realized that by hearing it up I caused the SO2 to vaporize and absorb the heat that I was putting into it! I tried another area and got the same result. As a scientific standard test I heated the deck for the same time and it got very very hot. This proves to me without a doubt that it should have enough refrigerant to satisfy the float in a regular manner. Now the question is how to make it behave.
What I want to try is to open and close the float repeatedly by putting the hermetic kit on and opening it up wide and closing it several times while the machine is on. Travis and I were discussing whether this would even work or not. The manual doesn’t state any year range of floats that have or don’t have the lifting spring. To me this means that my DR should have one, even though it is a late model DR. To him, he thought that they stopped putting that spring in at some point during the run. Does anyone know the truth? I’d be curious to find out.
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Post by turbokinetic on Oct 30, 2018 15:59:20 GMT
Very good points Birkie. I bet the evaporator wasn’t sucked completely dry since I had only run it for 10 minutes or so. It was probably just starved of refrigerant and that’s why it felt cool but not cold. I did the test last night. I let it run for about 10 minutes. At first it acted like it would cooperate, as it does. But to my surprise the watts didn’t start dropping immediately after the first audible opening. Instead they stayed steady for about 2 minutes. I was very happy with this and thought it might start to behave as I could hear the float letting refrigerant by at a very constant rate. Then it shut closed again. It started to rattle and the watts dropped. After about 8 minutes of that I decided to shut it down and break out the heat gun. I heated the bottom half of the evaporator in one specific area. As soon as I turned off the gun I could hear a faint boiling. At first I couldn’t hear it but as my ear adjusted it was clearly boiling. Just not the usual violent boil in the evaporator that I’m used to. This is the cool part though. I carefully touched the coil and to my surprise it was room temperature. This baffled me at first but then I realized that by hearing it up I caused the SO2 to vaporize and absorb the heat that I was putting into it! I tried another area and got the same result. As a scientific standard test I heated the deck for the same time and it got very very hot. This proves to me without a doubt that it should have enough refrigerant to satisfy the float in a regular manner. Now the question is how to make it behave. What I want to try is to open and close the float repeatedly by putting the hermetic kit on and opening it up wide and closing it several times while the machine is on. Travis and I were discussing whether this would even work or not. The manual doesn’t state any year range of floats that have or don’t have the lifting spring. To me this means that my DR should have one, even though it is a late model DR. To him, he thought that they stopped putting that spring in at some point during the run. Does anyone know the truth? I’d be curious to find out. If you're going to hook up to the system, why not try some of the Supco 88 oil additive? I believe Gill and others have had great success with it.
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Post by ckfan on Oct 30, 2018 17:07:56 GMT
Yes, I want to try it for sure. I would like to put some in all of my SO2 machines ideally. I think that I would need some SO2 to force it in though. I can’t think of a way to draw it in with a vacuum.
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Post by birkie on Oct 30, 2018 17:51:14 GMT
I bet the evaporator wasn’t sucked completely dry since I had only run it for 10 minutes or so. It was probably just starved of refrigerant and that’s why it felt cool but not cold. Therein lies the conundrum. If the compressor is running, and the evaporator has ample liquid refrigerant in it, then why isn't that liquid boiling? Follow-up question: How much refrigerant is in the high-side when this is happening? Has it filled the float chamber and now it's backing its way up the condenser (which is what happens when there is a stuck float), or is the float at the normal level, but it's just not getting any liquid refrigerant from the condenser any more? Hitting the lowest part of the condenser coil with a heat gun and listening for boiling would answer that question, as would cracking open the purge screw and seeing if liquid comes out. If you're going to put a service kit on it, that'll give an opportunity to see what the high-side is doing as far as pressure. Unless it is bound or stuck, it should work if it has the spring. While I haven't verified firsthand for the D2, I believe it is the same construction discussed in this 1932 patent. We got some circulation going in joneske's DRA2 by opening the float like this, enough to frost the liquid line with the valve held wide open (but the suspected problem there is low refrigerant levels due to a suspected leak).
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Post by turbokinetic on Oct 30, 2018 20:34:38 GMT
Yes, I want to try it for sure. I would like to put some in all of my SO2 machines ideally. I think that I would need some SO2 to force it in though. I can’t think of a way to draw it in with a vacuum. Use the SO2 to drive it in.
Fill a small receiver with the oil additive. Connect it to the system and draw vacuum in the receiver, hoses, and other parts before opening the unit's service valve.
Open the service valve with the unit running, so that a lot of SO2 pressure goes into the receiver.
Hold the receiver so that the outlet is the low point. Stop the compressor on the unit. Apply heat to the receiver to boil off the SO2, thereby pushing the oil additive down the hose into the unit.
That's how I would try to do it.
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Post by ckfan on Oct 31, 2018 1:31:35 GMT
I was able to get boiling near the bottom of the condenser so I think that should rule out the possibility of a low charge. I also got boiling midway in the condenser as well so it was backed up quite a ways.
That makes sense David. I bet that would work well.
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Post by birkie on Oct 31, 2018 1:48:32 GMT
I was able to get boiling near the bottom of the condenser so I think that should rule out the possibility of a low charge. I also got boiling midway in the condenser as well so it was backed up quite a ways. Ugh, sorry to hear that. I was hoping surgery could be avoided, but the prospects of that seem to be dimming. Maybe some miracle will happen when you open it up enough to lift the float. I'd use the heat gun to chase the SO2 out of the float and condenser before hooking up the service kit, but I'm kind of a 🐔 when it comes to releasing SO2.
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Post by ckfan on Oct 31, 2018 1:57:27 GMT
I’m a chicken about it too. When I just barely cracked the purge screw it sent me flying across the room!
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