Proper Way of Topping off a Compressor

[mobiledynamics]

Is the only correct way to top off a unit is to recover, repair leak, pressure test, weigh in....

2 of our mini splits were a bit low...one was literally flat I presume and the other was low (unit was freezing up).
Thankfully the HVAC service was prompt in this recent heat wave...just topped it off, added some dye and off they went to put out another fire I suppose.....was happy enough they were able to give me a morning slot the following day as is.

Probably a slow leak somewhere and another problem to deal with correctly another day.....It's 101F today.

With that said, is there a specific use where one just adds in refrigerant via the gauges vs. always doing a full vac and weigh in

 

[theoldwizard1]

Is the only correct way to top off a unit is to recover, repair leak, pressure test, weigh in....

Yes

 

[fitter30]

Mini split charge has to be weighed in. Being variable volume refrigerate flow it would be by the swag (scientific wide *** guess) method unless had the factory program to see where he compressor is running and evap unit.

 

[mm08822]

Mini split charge has to be weighed in. Being variable volume refrigerate flow it would be by the swag (scientific wide *** guess) method unless had the factory program to see where he compressor is running and evap unit.

But also adding or subtracting to account for the installed line set length, no?

 

[Snapped-off]

Yes

Incorrect. Might want to evacuate it before charging it...

 

[Snapped-off]

Is the only correct way to top off a unit is to recover, repair leak, pressure test, weigh in....

2 of our mini splits were a bit low...one was literally flat I presume and the other was low (unit was freezing up).
Thankfully the HVAC service was prompt in this recent heat wave...just topped it off, added some dye and off they went to put out another fire I suppose.....was happy enough they were able to give me a morning slot the following day as is.

Probably a slow leak somewhere and another problem to deal with correctly another day.....It's 101F today.

With that said, is there a specific use where one just adds in refrigerant via the gauges vs. always doing a full vac and weigh in

Might be able to see where they're leaking from if your comfortable spraying some soap on them.

 

[bonneyman]

Mini split charge has to be weighed in. Being variable volume refrigerate flow it would be by the swag (scientific wide *** guess) method unless had the factory program to see where he compressor is running and evap unit.

10-4 Only proper way to do it.
If the factory supplied lineset was used then just evacuate the system, add the charge by weight off of the condensing unit label, and run check. The lineset being shorter or longer requires adjustments depending on diameter and length. Some computations needed.
You should probably add some refrigerant oil compatible with the compressor oil charge as a freon leak will also leak oil. I use a small oil addition tool to add an ounce or two (also works for the leak dye charge).
This is similar to the one I used. Refrigerant specific.

Pardon Our Interruption...

 

[whateg01]

In a pinch like that, I've added a bit at a time until I'm comfortable with its performance. Better to undercharge than over, imo.

 

[Dagny]

If a refrigeration system has a single component refrigerant. not a blend and still has a substantial amount of charge left in it. Add some. If it has a receiver an sight glass its easy if not read up on superheat and subcooling to obtain proper charge. blended refrigerants **** because if there is a leak the recipe can change and most likely you have no way of telling how much of each component has leaked

No system with a known leak should have a vacuum pulled on it as air will be introduced. I never use vacuum to leak test. pressurize with dry nitrogen find and fix the leak then evacuate using a micron gauge. The refrigeration industry has been in chaos for a long time and billions of dollars have been lost or made depending on your point of view.

 

[American Locomotive]

Traditional fixed-speed split systems can be recharged without a whole evacuation by monitoring subcooling or superheat depending on if they use a TXV or a fixed orifice.

Minisplits on the other hand typically cannot be charged by this method, as you don't have access to the actual "high side" of the system, and thus can't measure subcooling. Plus, they typically have variable condenser fans, compressors and evaporator fans, making traditional subcooling/superheat/whatever measurements less than useful. So on these systems, you must charge them by weighing in the nameplate amount + extra lineset charge if applicable. The only way to do that is of course to fully evacuate the system so you start empty.

 

[fitter30]

Any installer that doesn't write the length of lines and added charge should be hung out dry! Under the electrical terminal cover or top of unit.

 

[bonneyman]

Any installer that doesn't write the length of lines and added charge should be hung out dry! Under the electrical terminal cover or top of unit.

If they did that, then there'd be basically no HVAC technicians!

 

[dscheidt]

If a refrigeration system has a single component refrigerant. not a blend and still has a substantial amount of charge left in it. Add some. If it has a receiver an sight glass its easy if not read up on superheat and subcooling to obtain proper charge. blended refrigerants **** because if there is a leak the recipe can change and most likely you have no way of telling how much of each component has leaked

minisplits are variable flow, and you don't know (because the manufacturer doesn't publish) what the superheat or subcooling performance should be. So the only way to do it is evacuate, fix the leak, and add the correct charge back.

 

[Aileron]

minisplits are variable flow, and you don't know (because the manufacturer doesn't publish) what the superheat or subcooling performance should be. So the only way to do it is evacuate, fix the leak, and add the correct charge back.

Or go to the factory schooling classes to be able to even buy the service tool for the computer to read the info. Daiken was a 5 day class to get access to buy the tool. METU was 3 day but dont think it was actual requirement for the tool, but the class taught how to use it.
For all those that think the companies are screwing them becuase they could screw there own line set together , what would it cost for your business to send a tech to school for 5 days. Add in out of town expenses also. You have to remember also , that tech has their name tied to the certificate also, if they leave so does the certification.

 

[Snapped-off]

Or go to the factory schooling classes to be able to even buy the service tool for the computer to read the info. Daiken was a 5 day class to get access to buy the tool. METU was 3 day but dont think it was actual requirement for the tool, but the class taught how to use it.
For all those that think the companies are screwing them becuase they could screw there own line set together , what would it cost for your business to send a tech to school for 5 days. Add in out of town expenses also. You have to remember also , that tech has their name tied to the certificate also, if they leave so does the certification.

The Danfoss Turbocor compressor class is expensive.

 

[Aileron]

^^ I was sent up to Smardt in Canada for a week coarse been about 12 years ago,.