Subcooling Charging Method, explained, what is normal subcooling for R22?

Before you call and ask a senior tech what your subcool should be, read this article.It's the one you send to the junior tech when they call.

Subcooling is a measurement of the temperature of a liquid below its saturation.

Water is boiled at sea level at an atmospheric pressure of 14.7 PSIA.It is possible to determine if the water is at saturation by looking at the atmospheric pressure at sea level.If you measure the water at 202, you can be certain that it is fully liquid and not in the process of either boiling or changing from vapor to liquid.We know that the water is liquid because it is at 202 instead of 212.This 10 of subcooling PROVES that is fully liquid but that it has given up more sensible heat energy, enough to drop 10 degrees below the boiling temperature at that pressure.

It gives us a lot of information when we measure the subcooling between the condenser and the metering device.When viewed in conjunction with the high side saturation temperature, it gives us indications of refrigerant charge and condenser efficiency, as well as whether or not the line is full of liquid.Be careful now.It is just as accurate as your tools.You must have a good connection to the port and take it using liquid line pressure and temperature.I can't tell you how many times green techs have called me with crazy readings only to find out their hose was not depressing the Schrader core fully.

The most common place for subcooling is the outlet of the coil.You need to look for proper design subcooling for the system you are working on.For maximum efficiency and capacity, some systems will need subcooling readings of up to 16.

Subcooling is a way to set a charge on a TXV/TEV/EEV metering device system.

If you want to set a charge, you need to make sure that your equipment is compatible with the correct metering device.You can monitor your progress by using a scale when you add or remove a charge.

Subcooling is the primary charging measurement on a TXV/TEV/EEV system, but it is important to check on every system whenever possible.

Negative Subcooling can't be done if the liquid line temperature and pressure are the same.A miscalibration of your tools can make zero sub cooling look like negative subcooling.

In cases where the system is designed to inject discharge gas into the liquid line on purpose to increase liquid pressure, Zero Subcooling is not an acceptable condition.

A low subcooling is an indication that there isn't enough refrigerant in the condenser.This can be a result of under charge, poor compression, or a metering device failing open.

High Subcooling is an indication of more than the designed amount of refrigerant.Overcharge, restriction, or an undersized or failing closed metering device are some of the causes of this.

The subcooling can read in range on a system that still has issues.The previous tech simply set the charge by subcooling without fully testing all aspects of the equipment.

I don't think I would be able to tell if it was over charged.There could be other reasons for high head.Would the receiver allow you to read subcool?