U S Air Force HVAC tech in Baghdad tasked with the following........... Take one 4.5 ton R-22 Environmental Control Unit (ECU) and ATTEMPT to make it operate on R-134a. This is NOT a joke, the request came from a man who wears eagles on his collar.
I'm looking for guidance on replacing the 208-230v 3 ph hermetic compressor with a comparable unit that is 134a compatable. Also need the matching TEV/TXV. Our most modern ECU runs on 134a but uses a massive scroll compressor that physically won't fit in place of the current hermetic. It does however have an expansion valve that I may be able to utilize.
Time is short and this is a serious request for help.
Why would he want to put a 38 caliber bullet into a 45?
Capacity issues, Oil issues, metering issues.
Contact the Dupont refrigerant hotline for details and information on the best swap for your application.
Tell him it can't be done and then explain why.
Originally Posted by ar4s1
A bird is most likely not the CE commander. So why dont you have your commander explain some physics or have your Chief tell him like it is!
Chief would probably get better results.
Then have them Dumbo drop you a new HB in.
Since when is a Colonel not a Commander of a unit?
I love to Cook...HVAC is a hobby that pays the bills!
A Full Bird in Command of Civil Engineering, doesnt happen or least it did not use too. A Light Colonel, Yes, but not a Bird.
Originally Posted by makinmoney
I can't give an ounce of advice on your problem, but thanks for your service to our country!!
Originally Posted by ar4s1
Hope ya get it figured out!!!
Brings back memories when I was in the USAF, I know you are in a tight spot I'm gonna recommend (this is the best I can do): use PROPANE R-290 They are pretty comperable in net capacity The boiling points of R-22 and R-290 are sufficiently near over the selected temperature range. The 134a is pretty far fetch idea Good luck bro.
WARNING:IF YOU DON'T KNOW THEN DON'T DO, SO THOSE WHO KNOW WHAT YOU DIDN'T KNOW DON'T END UP UNDOING WHAT YOU DID SO IT COULD GET DONE RIGHT!
The Colonel is THE Civil Engineer for the Air Force Central Command, the why is because the current R-134a unit is all electronic with digital controls. FAR too complex to teach my entry level troops and FAR too fragile for this environment. It's a good unit, just not for here.
"It won't work" isn't an option! I need to make a valid attempt. He's not looking to have a 100% fully operational unit, only a base line for a possibility of keeping the base platform of the current electro-mechanical R-22 unit, only being produced in an R-134a variant. I understand the coils will be mis-sized and a list of other things won't be perfect, but those issues can be resolved by design engineers later. He's just trying to get us to keep the unit that we all love to work on and is simple and reliable enough to be used here in the desert. Plus if the findings come from me, then it doesn't look like this is his idea but comes from the troops in the field.
Surely one of my HVAC brothers out there can give me a manufacturer and model number for a 208-230volt, 3 phase, 50/60 Hz 5 ton R-134a compressor. It can even be a scroll provided it fits in the space allowed. The TXV from the new R-134a unit will work at least for now.
The reason is not clear!
Please explain the reason or what you are trying to accomplish.
Can you not get the R22?
Is the compressor shot on the R22 unit?
Are you trying to reduce capacity?
R22 is still available, just not in a new unit.
The oil in the 134A unit is most likely POE synthetic.
The oil in the R22 unit is mineral.
If you are going to use the old r22 system the oil will have to be changed until all of the mineral oil is removed. (less than 5%
The cooling capacity of the 134A is 1/3 less than the R22 using the current setup. (R22 compressor and coils)
If at all posible, do not scrap the r22 system. Fix it.
The compressor size will increase if you want 5 tons on 134a. A higher volume must be pumped. I question the reasoning and the amount of work involved. Without design information on the coils, I think you are getting in over your head. I would like to help...but you are changing design.
Can you get R417A? It is a drop in blend to replace R22 with almost the same capacity, it likes mineral oil, it makes sense.
Last edited by ACCMan; 02-08-2008 at 05:30 PM.
Reason: Request not feasible
Change the controls on the new unit.
I reread your original request. Have you considered changing out the controls on the new unit to mechanical controls. The warranty will be gone...but a high and low pressure switch and a mechanical t-stat would take care of your problem. Fan cycling switch for cold nights.
You would then have a simple mechanical system designed for its refrigerant.
If you tell what unit you have, I can supply you loads of operating info.
I hope I've helped.
If you ever want to do anything besides baby sit that unit, try to fix up the r-22 one that you have. You'll have so many problems you won't sleep at night
I'm not tolerating Political Correctness anymore, from now on it's tell it like it is.
Veto Pro Pak - The best tool bag you'll ever own
Good call. I like that idea. The mechanics of both units are the same, rip the digital crap off and go with simple mechanical controls.
Originally Posted by ACCMan