I need help with this HVAC label.......

[kwired]

My point is back in the 'old days' it was common to charge a unit to FLA. It was also common to see a lot of compressors with burned windings. Units were super no efficiency and tripping overloads were common. Compressor manufacturers were seeing too many compressors failing in the first year. (their warranty period) Switching to RLA decreased the rating of the compressor but also prolonged the life of the compressor.


While you are correct that some compressors are rated in btu's many are designed to use multiple refrigerants and operate at different pressures and btu's.

True an individual compressor can be used in more then one different machine, but the nameplate on an individual machine is the rating for that machine.

AFAIK charging according to amps pulled is a poor method, the way it should be done is to determine superheat and charge accordingly.

 

[Mgraw]

True an individual compressor can be used in more then one different machine, but the nameplate on an individual machine is the rating for that machine.

AFAIK charging according to amps pulled is a poor method, the way it should be done is to determine superheat and charge accordingly.

The nameplate may change but the RLA will be the same.


Yes charging by amps alone is not a good method but 45 years ago it was common.

Superheat alone is not the best method. Superheat, sub-cooling, low side pressure, high side pressure, amp draw, indoor temp, and outdoor temp are all needed to properly charge a unit.

 

[kwired]

The nameplate may change but the RLA will be the same.


Yes charging by amps alone is not a good method but 45 years ago it was common.

Superheat alone is not the best method. Superheat, sub-cooling, low side pressure, high side pressure, amp draw, indoor temp, and outdoor temp are all needed to properly charge a unit.

Did they at least consider what temperature was or did they just add charge until it reached FLA/RLA?:?

Actual running amps is going to be different on a 50 degree day then it is on a 100 degree day, then you still have to factor indoor temperature, potentially clogged filter and other things that might change actual running amps.

 

[Mgraw]

Did they at least consider what temperature was or did they just add charge until it reached FLA/RLA?:?

Actual running amps is going to be different on a 50 degree day then it is on a 100 degree day, then you still have to factor indoor temperature, potentially clogged filter and other things that might change actual running amps.

I was fortunate to have a retired Carrier trouble shooter as an instructor in trade school. Carrier at that time was trying to get a handle on the huge amount of first year compressor failures they were experiencing. They started requiring failed compressors be sealed when returned for warranty. Testing was done on returned compressors from contractors that had larger than normal returns. The vast majority were due to overcharging on start up. Some were due to moisture not being removed. They started doing inspections on installations and found a lot of contractors would dump refrigerant until at FLA. Remove gauges and move on to the next job. They dumped a lot of contractors as dealers.


The first company I went to work for had "old timers" that charged cap tube systems the same way. I destroyed a lot of ozone dumping excess refrigerant.