I wonder if that's why some systems (like window air conditioners) seem to take quite a bit of time to reach ideal steady-state performance after sitting for a while? Logically you'd think it'd only take a minute or so for the evap to get down to operating temperature. That might not be the case though, if a significant proportion of your charge gets absorbed into the compressor oil! Seems like you'd have to wait until all of the refrigerant boiled out of the oil before you'd reach ideal performance.
Probably very true! Another thing about window units is this; they commonly have high-side housing rotary compressors. Those trap refrigerant in the housing until the motor warms up. They often start out with only a few passes of the evaporator cooling; and frosted over, then gradually cool more and more of the evaporator as the compressor warms up.
It's a neat piece! Embraco has clear acrylic housings for sales samples. They do run but aren't a pressure vessel and are just demo pieces. Would love to see one made of a heavy enough material to hold pressure.
So that's why compressors can be a bit noisy at first - gas being driven out of the oil? Did you post a video about your DIY recovery machine? I don't see it when I search your channel.
The oil foaming is probably part of the increased sound level at startup, but I think that the high suction pressure plays a bigger roll. Once the low side pulls down to more normal operating levels the sound is less. I did a video on the recovery unit, with it here. I had planned to do follow-ups but have not. There is only a part 1 so far: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE--PHbWz1pHCo.html The recovery unit is working well, though.
I wonder if when they were putting the oil in there at the factory if they filled it by level or volume. obviously the area that the window is in would need extra oil to fill up. Hopefully they did it by height and knew what part of the compressor internals the oil should be up to for maximum effectiveness but keeping if off the spinning part as much as possible. Glad you found it on eBay. Definitely a cool piece.
Thanks! I had thought about that, as well. The window area does add volume for sure. In the center, there is an oil pickup tube which almost touches the bottom of the casing, so the oil only needs to have about 1/4" in the very bottom to reach the tube. Not saying that is an OK operating level, but it would still be able to pick it up at that level.
WQould guess part of the reason was that they also wanted to see how the compressor block handled motion of the RV in operation, as the fridge freezer would likely be in operation with the vehicle in motion as well, so wanted to be sure of it not hitting bump stops, and also yes oil foaming during start up, as they likely had long lines, which meant lots of refrigerant in there in operation.
Makes sense about the bump stops in a mobile environment for sure. And the refrigerant volume in my "test" system is excessive for this compressor design since it's a flooded evaporator design. Worst case scenario more or less.
How do you feel about Embraco compressors? My mother has a fridge which has one, and it is only around 5 or 6 years old, and it sounds terrbible. Especially when starting, it sounds very metallic; it quiets down some after it has been running but not too much. Meanwhile I have compressors that are over 30, 40, and even 60 years old that still run great and sound like new.
Walter; they are very well engineered, but as with many consumer grade products, the manufacturing does not do justice to the engineering. When you get a "good" one they last a very long time and are quiet. This design is a follow-up to the old Tecumseh AE series. It's been improved and modified but it has heritage back to those days. This design has a tendency for the wrist pin to go bad and cause a "bell ringing" or a "zinging" noise. That area has been reinforced over and over but sometimes you still get failures. I've seen random winding failures, wrist pins, stator rubs, broken reeds, etc. They were due to manufacturing variances which shortened the life of the unit. Another issue occurring of late is poor lubrication. The lubricants have very little viscosity and film strength. This is to minimize pumping losses and therefore make energy usage numbers to meet pointless government standards. This can lead to failures because it's easier than you might expect to exceed the operating limits of the oil. Here is a video where I tear down one. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-DpnnLQNgUiQ.html
@@davida1hiwaaynet Interesting. I remember the old Tecumseh AE units, in fact I have a few air conditioners which use them. Those seem to have held up very well to years of abuse.
@@WalterKnox They do hold up well! There are millions of them out there. I have cut open a few and all of them which had locked up had done so due to wrist pin failures. That is just a very small number out of millions. Remember I have a repair shop so all I see are broken, damaged, and discarded ones. All I see are failures and all of the failures I saw of that model were wrist pins. There is probably only a tiny chance that the wrist pin will fail, or that the compressor will fail for any reason. But for the very few of them overall which do fail, the failed ones are likely to have a bad wrist pin.
Did this compesser have mineral oil? I don't remember if you said what refrigerant you used. It would be interesting to try with R134. I wonder if the lack of misciblity would mimick sulfer dioxide as far as oil return?
I expect this has POE (polyol ester) oil, since it's a factory R134A compressor. I am running R152A which has same oil miscibility as R134A so the effect would likely be identical.
It's almost certainly ester. PAG is destructive on motor windings and is generally used only in mechanical drive compressors, such as auto air conditioning.
How do these compressors suction gas into the piston? Trough an opening at the top, near where the actual piston is? So there's little probability that it can suction liquid oil/refrigerant in a startup such as this?
Thanks for the comment! There are no reeds in the piston with this design. It has two sets of reeds in the head. The inlet reed draws through a suction muffler. The inlet from the muffler is extended up to the top center area of the housing. The oil foam would have to reach the very top of the housing to get drawn into the cylinder. This can happen, with extreme foaming, though.
@@davida1hiwaaynet one more question. After the oil level drops below where the rotor swirls it arround. How do the moving parts lubricate? With the oil mist moving with the refrigerant?
@@TalasDS It is hard to see in the video, but there is a dip tube in the center of the compressor. It goes almost all the way down to the bottom of the housing. It is uses a centrifugal pump design to lift the oil up to the top of the compressor, where it is discharged into the bearings and other moving parts. That is the source of the oil droplets flying around in the housing.
I dont see an email for you anywhere. I dont have Facebook or twiter or any social engineering apps. I am a licensed hvac tech and would like to connect as i am doing refrigerator restorations here in New Hampshire.
@DavidAllen this is the kit I got sir I will post it on my channel in the community section. I've seen kits with more but this looks about right .Imperial Service Valve Kit For Hermetic Units with Marsh Gauge Also thank you for your vids. I don't see a lot of people who put in the work to make things proper.
They hide creators' e-mail to protect against spammers. The visibility depends on your device and other factors they won't tell us about. I will share my e-mail here, but you will have to assemble the parts to get the complete address davida1 at hiwaay dot net is it. Same as my channel name, plus the necessary characters to make an e-mail.
