how to charge 410a system after vacuum

During air conditioning mode, the pressure on the vapor line of an R-410A system will be somewhere between 102 to 145 PSIG. The only time a technician would add refrigerant into the liquid line of an air conditioning system is if the system is off, empty, and vacuumed.

Vacuum the system (Deep and Standing vacuum required as on modern refrigerant/oil) 3. Likewise, an R-410A recovery bottle with a surrounding air temperature of 75°F should have an internal pressure of 217 PSIG. The pressure in the bottle is much higher than the pressure on the low side of the system so if they are connected, refrigerant will exit the bottle and enter the system. The higher the heat load on the inside of the building, the higher the pressure will be on the vapor line. This is because the liquid line is small and will not allow the refrigerant to vaporize as quickly as the larger vapor line would.

Likewise, an R-410A recovery bottle with a surrounding air temperature of 70°F should have an internal pressure of 201 PSIG. Now tight both the low and high-pressure side hose at position C & D respectively as shown in the image. Craig is a licensed Teacher of HVACR, Sheet Metal, and Building Maintenance in the State of New Jersey of the USA. To learn more about contaminated refrigerant problems, check out our, On a running system, the liquid pressure does not have a consistent range like the vapor pressure does. The charging cylinder uses tables and scales for different refrigerants at different temperatures so that we can make a very accurate refrigerant charge. However, the technician needs to be able to check the charge while adding refrigerant in order to know how much to add unless they are charging by weight per foot of line set. He is also an HVACR Contracting Business owner of 15 years and holds an NJ HVACR Master License. This also results in a higher vapor pressure. In our book we go over many of the methods that have been used to try to short cut checking the refrigerant charge the correct way. It is crucial to check the recovery bottle pressure before use!

If the superheat temperature is high, then it means the system is running low in refrigerant whereas lower superheat temperature than the desired value means the system has overcharged. For business related inquires email us at info@acservicetech.com. The first thing to realize is that when a system is off and equalized, the system’s pressures on both the high side and the low-pressure side will match. Your email address will not be published. Now, coming back to charging up an HVAC system running short of refrigerant.

The red one is connected to the dip tube and is for the liquid charging. Connect the liquid and gas line hose and purge it. This allows less saturated refrigerant to be inside the vapor line for the initial start-up.

It’s very important to weigh the charging bottle before charging and log down the amount of refrigerant charged. All the refrigeration systems are designed to run without moisture and non-condensable gases else it may not work as designed and is likely to fail prematurely.

However, this method should not be used for recovering large amounts of refrigerant because mixed in with the high-pressure liquid will be the system’s oil. If a new R-410A refrigerant bottle had a surrounding air temperature of 70°F, the pressure inside the bottle would be 201 PSIG.

We have a 1,000 question workbook with an answer key that you can use to apply your knowledge as well. Remember that after the refrigerant vaporizes, it will apply pressure inside the system and this pressure will increase to the same pressure as the pressure inside the bottle. If the outdoor temperature is 70°F, a refrigerant bottle outside would have a pressure of roughly 201 PSIG.