|
|
Post by cablehack on Aug 13, 2013 1:36:12 GMT
One of the FAQ's about monitor tops is always about using modern refrigerants to replace S02. There will always be those preferring not to use S02, and many antique refrigerators have been scrapped for this reason. For example; this pristine condition CF.As mentioned in the 1934-42 service manual, GE did issue a modified CK type compressor for use on Freon 12. It was used in some of the late CK-3 rebuilt Monitor Tops, and some of the ordinary production Flatops. The piston stroke was shortened slightly for the higher pressure (details in the manual). As piston modification is only for the die hard enthusiast, a simple external modification found in Norge literature has apparently brought forth excellent results. So, I wonder if those who have done conversions would like to post the details of how to go about this. What tweaks were required for Monitor Top use? I understand that R134a is more suited to the modification than R12. To date, I'm aware of Coldspaces and jhigdon converting DR's and CK's to R134a, and also u1984 using Hot Shot in a CK. There was also someone in the Yahoo group with a CK running on hydrocarbons.  |
|
|
|
Post by coldspaces on Aug 13, 2013 4:24:41 GMT
Yes you can make them work on modern refrigerants like 134a, and even end up with comparable power consumption as documented by jhigdon2. When I first got my Monitor top I could not get it to cool good and it smelled like so2 inside the cabinet. This made me believe it was low on so2, not sure it was as the oil heater was not working at that time and I did not realize it even had one. After I removed the so2 and evacuated it good I tried filling it with R-12 and did not get the best results. After getting a heater for the oil I was never able to get the high side float to want to open on its own and let the R-12 flow right. If I forced the float to open with rapid bleeding of gas off of the top of the float or by using the Bristol tool to open it I was able to get it to work and cycle on and off with fairly good power consumption. After trying everything including a R-12 charge as much as 6 lbs I decided R-12 was just too dense and was not able to readily make it out of the compressor shell on the DR-2 unit. Being the shell is on the high side it just seemed to want to stay there. I think a Ck unit would work better since it is a low side shell and would pump the R-12 out the discharge tube an out of the shell much easier. Either way noise is a real factor,the R-12 is so much denser than so2 that the compressor was a lot louder on my DR and I am sure would be on a CK so2 unit. This is where the suction line restrictor saved the day. By controlling the flow to the compressor there was much less noise but still much more than so2. After I decided that R-12 was just not gonna work good I wanted to try 134a but was worried about using POE oil in the old compressor. Thats when jhigdon2 explained to me that so2 and mineral oil don't mix well either and the flooded evaporator is key to proper oil return. The mineral oil floats on top of the liquid refrigerant in the evap and is then at the proper level to be returned to the compressor. When I filled it with the 134a it immediately worked like a completely different machine. The float opened on its own and it worked great for 3 straight weeks till the control stuck on. The 134a is more dense than so2 but also less dense that R-12 and with a suction line restrictor and 134a the refrigerating machine works great and noise is nowhere near as bad as R-12. In the end I had about 3 lbs of 134a in it and cycle times of 2&1/2 minutes on and 11 mins off in a 58F ambient. Here are the before and after pics of the 5" x 1/8" ID restrictor tube I installed.   |
|
|
|
Post by allan on Oct 23, 2013 21:43:48 GMT
Is this a DR with a stainless evaporator? Is it still working?
|
|
|
|
Post by allan on Oct 23, 2013 21:49:56 GMT
Is this a DR with a stainless evaporator? Is it still working? And I assume you left the mineral oil in |
|
|
|
Post by coldspaces on Oct 24, 2013 1:00:14 GMT
Is this a DR with a stainless evaporator? Is it still working? And I assume you left the mineral oil in Yes I did. I was worried about the new POE oil being compatible with the old compressor materials, that's when jhigdon2 explained to me that so2 and mineral oil did not mix well. The flooded evap causes the oil to float to the top and be removed. He had run one on 134A for a year without trouble, but did not like the noise level of the compressor. After adding the suction line restrictor he got good noise level and real good cycle times. After the conversion on mine I ran it 3 straight weeks till the contacts in the control stuck on. Since then I have had it on part of the time and off part of the time. Been on again for the last 4-5 days and working great. Oh and if i remember right I believe he used a bit longer restrictor tube that I did, mine was 5" I think he used 6". And yes it is a DR with a stainless evap. Best we can tell it must be a factory reconditioned unit. Here is the discussion in the flickr group from when I tried the r-12 and then 134a www.flickr.com/groups/monitortops/discuss/72157633145716724/ |
|
|
|
Post by coldspaces on Mar 18, 2015 22:00:10 GMT
I has now been over 24 months since I first charged my DR2 with 134a. I do not know the exact day but the original discussion in the Flickr group shows its been 24 months now. www.flickr.com/groups/monitortops/discuss/72157633145716724/It has ran non stop(other than a few defrosts)since I rebuilt the control in November of 2013. So far no sign of any oil return problems or any other problems either. Best part is the beverages are good and cold! |
|
|
|
Post by cablehack on Mar 19, 2015 0:34:34 GMT
I has now been over 24 months since I first charged my DR2 with 134a. I do not know the exact day but the original discussion in the Flickr group shows its been 24 months now. www.flickr.com/groups/monitortops/discuss/72157633145716724/It has ran non stop(other than a few defrosts)since I rebuilt the control in November of 2013. So far no sign of any oil return problems or any other problems either. Best part is the beverages are good and cold! Those pioneering days seem so long ago, but yes you're right it was not long after 1st April 2013. It always takes time to test something like this; not like other appliances where you know straight away if a modification works. I think we can now officially approve R134a as an SO2 replacement in DR2's. |
|
|
|
Post by tholius on Aug 13, 2016 19:24:32 GMT
I have a CK and I rewired it, and the compressor runs fine. The tubing out of the float had one that came out into a T back into the other line, but it was factory crimped as though this was what they did after charging. I installed my charging port in this line, after the crimp where the T was, leak checked and evacuated everything, and put 3 pounds of 134A in but it isn't cooling. I'm not a cooling guy, just handy, any suggestions for what to do next?
|
|
|
|
Post by coldspaces on Jan 14, 2017 2:43:14 GMT
So for the last several months I have been checking out so many refrigerants I can't remember them all with out my "war board" to try to help keep things organized. I am learning a lot along the way about the new refrigerants that are comming that will affect my life at work before I even what to think about it, so I am getting double benefit from all my work I guess. Of course my hope was to find one or more drop in (or near drop in) replacements for so2. I mostly looked for ones close to the pressure of so2, then checked their other specs to see if they were close. R124 is similar pressure and replaces r114 in hi temp Ac applications. It is a HCFC though so its days are numbered. Its available now relatively reasonable but not stocked at the average local supply house. It is also denser than so2 and less than 1/2 the BTU per lb. I have wanted to try R227ea for a long time but it is almost only used as a fire suppressant here in the states. I could buy a small amount to try from a fire equipment place but it is already pressurized to 300 psi with nitrogen for fire use so that won't cut it. If I special ordered 30 lbs i could get it but its over $1,200 wholesale and also denser and and lower BTU. Could also get some r245FA, $600 is all, would love to have a few lbs first to try. It looks fairly promising with similar pressures and liquid density, vapor density and molecular weight is higher though. Also not the best global warming factor if I remember right. I would try others if I could but have no access to them, either they are too new or just not used in the states (at least so far) So a couple nights ago I went back through the 14 page list from Wikipedia, this time highlighting the molecular weight and the studying ones somewhat near the same as so2. That's when I saw that even though R152a is somewhat higher pressure than so2 and its a class A2 (mildly flammable) refrigerant, it has almost the exact same molecular weight, same vapor density, lower liquid density and if I can find the spec again I believe very similar BTUs per lb. Also even though its an HFC it has a fairly low global warming potential so it might get lucky and get to stay around a while I hope. Not a perfect match but maybe close enough. There is not a lot of gases that are this close so there will be more details coming on this gas. By the way it's what is used in keyboard dusters, except for some are filled with r134a, and almost all have a bitterant added to discourage huffing so you will want to try to avoid those if possible. Attachments:
|
|
|
|
Post by 100yearfridge on Jan 14, 2017 3:30:50 GMT
I know iso-butane has been discussed here before, I just thought I would toss some information supporting its use.. I thought the similarities between it and So2 is remarkable. The largest difference seems to be the liquid specific gravity. Wish they were better fidelity. Sorry |
|
|
|
Post by coldspaces on Jan 14, 2017 4:31:26 GMT
I wish I would have had those charts on my board before now! That is some great info all in just a few pages. I agree that r600a is real close but I am on a mission to find an class A1 refrigerant, not that that has happened yet. I would try some 600a if I had it but it doesn't get the scare factor out of saving these old refrigerating machines. We know that the chances are slim there will be a problem with less than class A1, that is till someone else puts the human factor into the mix. And don't forget I am expected to get the cinnamon roll scent into all this yet lol.
|
|
|
|
Post by ckfan on Jan 14, 2017 4:42:18 GMT
That is a serious board right there Gill. I like it! I honestly wouldn't mind using isobutane but as you mentioned you have to take the human factor into account. I am going to have to read up on the vast amount of refrigerants that are out there. It's interesting to see just how many there are.
|
|
|
|
Post by elec573 on Jan 14, 2017 4:58:48 GMT
Well coldspaces think your doing a good job!!!! Appreciate the new information, it would be great if we had a direct replacement for so2 but I know it may not be possible. Thanks for trying!!
|
|
|
|
Post by Travis on Jan 14, 2017 17:08:21 GMT
I promise not to ignite a DR
|
|
|
|
Post by 100yearfridge on Jan 14, 2017 18:53:08 GMT
I wish I would have had those charts on my board before now! That is some great info all in just a few pages. I agree that r600a is real close but I am on a mission to find an class A1 refrigerant, not that that has happened yet. I would try some 600a if I had it but it doesn't get the scare factor out of saving these old refrigerating machines. We know that the chances are slim there will be a problem with less than class A1, that is till someone else puts the human factor into the mix. And don't forget I am expected to get the cinnamon roll scent into all this yet lol. This book (4 editions) taught me more about mechanical refrigerators than any other resource. Harry Blair Hull (from Ohio) is by far my favorite author on the subject. A quick search of abebooks.com and eBay just now didn't turn up a single copy, other than an expensive reprint. I highly recommend acquiring a copy. The 4th edition is the largest, and includes the most information, but each one includes descriptions and illustrations not found in other editions. The first edition was the hardest to find and by far most expensive. I can recommend several others you may or may not have heard of. Althouse and Turnquist are always good; I have several spanning 15 years or more. This week I'll try to document my collection and post it somewhere. I share the concern about the human factor. The only thing I can do (if iso-butane works out) is get a nice r600a sticker, like they put on the compressors of current refrigerators with HC refrigerant. I figure I'll put it on the back, along with the charge size. It kind of takes away from the original look of the unit, but it won't be original anyway with different refrigerant and insulation. The important thing is that it runs. I'll probably never get to do this, but I would be very interested in seeing a MT far beyond saving, sacrificed for the benefit of others by being purposely filled with HC and ignited, just to see how hard it is to do, and how bad the horrific results are. Perhaps one of you out there has such a sad unit. Think of it like using a cadaver to benefit medical science. |
|
