Subcooling vs charge graph?

[Larry2]

I've looked for a graphical representation of subcooling vs charge but I've not found one anywhere. I have found charts of cooling performance vs charge and charts of efficiancy vs charge. Both charts were normalized to 1.0 representing nameplate charge. Those charts show the fixed orifice system to be pretty critical for charge while the txv system is somewhat more forgiving of error.

Can anyone post a chart of subcooling vs charge, normalized to 1.0 as nameplate rating?

[mcjo tech]

Not exactly sure what you are looking for. Could you be more specific. Most manufacturers list their subcooling specifications on the unit. However, their is a generic subcooling chart but I am not sure if that is your question.

[Larry2]

In the following pdf paper, on page 14 they show a graph of efficiancy vs percentage of nameplate charge.

http://www.eeba.org/conference/2004/presentations/Proctor1.pdf

I was looking for a simlar graphical represenation of subcooling vs percent of nameplate charge.

[Larry2]

I guess why I am interested in this graph is that with my poor performing compressor, I charged the system against subcooling, per the manufacture's instructions. I later recovered and weighed the total charge and it was high. I am trying to get the concepts straight in my mind of how charge amount, compressor delivery, and subcooling all relate. I am thinking that a poor performing compressor will lead one to overcharge when going by subcooling.

I suspect this graph of charge vs subcooling will approach a limit without a maximum. An underperfomring compressor would or could see liquid return before subcooling is at spec.

Am I right or am I lost as usual?

[frank]

There's more to it Larry than Sub-cooling.

You should be checking the compressor current draw, air on, air off of the indoor coil, air on, air off of the outdoor coil, superheat and sub-cooling and pressures, both discharge and suction.

You need the whole picture to be in a position to know if it is operating correctly