Have you thought about the new lubricant? It will wash all the old wax left over from the mineral oil into the expansion devices. The higher pressures are also a huge concern.
Moved to Tech to Tech commercial forum.
How about today's prices?
Originally Posted by ascj
I guess that that my prayer for you is a little too late. But now you must continue with a little hope.
As for the failure this was to be expected. As the others have stated, R-22 and 410A components should never be mixed. The equipment is not interchangeable. You now have a monster out of control.
It sounds like you have a tandem scroll compressor arrangement which will normally require replacement of both compressors. Sounds easy enough Huh?
I don't think so. Your compressor failed because a lack of oil. This was evident from the noise and the locking up of the scrolls. Now you will have to first clean up the mess. There are now fine metal micron fragments in the system which must be removed or expect another quick failure. You know the routine with a high capacity clean up suction filter/drier. You will also need to perform an acid test.
Having left behind some mineral oil and mixing with POE oil has resulted in the form of two liquids. This is a direct result of oil loss.
As for the remedy you will need to consider operation in a part loaded condition. The installation of a hot gas bypass line will need to be installed so that proper circulation of oil can be maintained and returned to the compressor. Liquid line size will need to be evaluated so as to maintain a minimum velocity of 260 feet per minute and a recommended maximum of 400 feet per minute. Suction Line size may need to be at least 1-5/8 or maybe even 2-1/8 so as to maintain proper oil return
REMEMBER: With 2 stage units you must look at the suction line velocity at reduced capacity to insure velocity remains above 1000fpm on suction risers. If it does not, reducing the riser size by one size will correct the problem
I will send you a sizing chart as an example for your use in the next post:
If you want I can email it as an excel file.
In addition I would remove the suction accumulator and install one sized correctly for your application. It sounds like you have a single circuit with one TXV.
The other problem that you will have is that when one compressor is running it will have the tendency to draw oil from the compressor which is off by means of oil misting. You will have to install a crankcase heater and possibly two so as to prevent this from happening.
The head pressure will also need to be maintained at a minimum set point and controlled by a speed controller such as a Penn/Johnson VFD 66 Drive and with the use of a pressure transducer P499.
I can go on but not tonight.
Troubleshooting is not part of the repair..............understand the symptoms and you will find a solution.
I know of some that were supposed to have POE and accidentally shipped with mineral ....
Trans paid 100% and provided the labor as well....
I think the biggest point missed here is R22 equipment and components are NOT safety rated for the higher pressure of R410a...
I'm converting my service van from gasoline to diesel to save money ...any ideas ....
Everybody who continues to perform work like this ,thanks for the future work....
And yes ,I know the OP.had his hands tied ,,,as I have in in the past....
The evap coils that were made 30 years go, and most other evap coils made pre 13 SEER min were made thicker then a coil made/rated for R410A today.
Originally Posted by mikeacman
Line sets today, aren't made any thicker then line sets 10, 20, 30 or more years ago.
The condenser coil of a new R410A unit has a thinner wall then the old evap coils do.
Your more than likely correct ...
but they still aren't rated from a liability standpoint ...
most evaps like that I've seen are pressure rated at 150 to 300 psig .
Dump a full charge in a room from a blowout and make people sick and see what happens when lawyers get involved....
That will never happen .... Famous last words
Absolutely no disrespect intended ,just my personal opinion
And with R22 options why go 410a???
Thank you for this thread, it's been educational.
Originally Posted by allstar08
They were only tested to that pressure since with R22 higher wasn't needed. Doesn't mean they could take more. And York and some other manufacturers admit they simply took their old r22 designed evap coils and retested them at higher pressure. they held, and they said ok, they're R410A rated. So a blow out wouldn't be as liable as you may think. As far as because it was from an "unapproved" coil. Same liability as a listed R410A coil.
Originally Posted by mikeacman
Why stick with R22, when its becoming more and more expensive.
Never said stick with R22,,,I said there are other options out there ....
Being called in the office one day with several other techs and being told that we were being sued over something we considered frivolous , or no big deal, has made me a little gun-shy..
Did you hear "looks as if Trane is having problems with their 15 ton scrolls" directly from Trane? Or is this wishful thinking/supply house rumor?
Originally Posted by allstar08
I think your words above would have more street cred if these 15 ton scroll failures were occurring in brand new 410A systems (the entire system, including evap, coils, linesets) at a rapid pace, systems that had not been converted from R22. Perhaps they are, but I personally would be asking that question were I told "we're seeing a lot of failures with these 15 ton scrolls and the factory is running of them" with no other qualifiers.
In your case I'm wondering if some time and $$ spent on RX11 flush may have made the difference between your scrolls failing or staying alive.
- Electricity makes refrigeration happen.
- Refrigeration makes the HVAC psychrometric process happen.
- HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.
A building is NOT beautiful unless it is also comfortable.