I have installed an Intertherm 4 ton heat pump. I can pull a vacuum on the system, but do not know how many pounds of refrigerant the unit requires.How many pounds does a 4 ton unit requier? I tried to contact the Intertherm web sites and none of their tabs have a customer question category?

All new refrigeration outside units come pre charged with the right amount of refrigerant as long as the connecting lines are within a specified length (usually 25 feet) to the cooling unit inside the house. Once the vacuum has been pulled you just open the valves on the outside unit. The installation guide should explain this, but if not, call the manufacturer.

Agree with Dr. Most all condensers come precharged. However, there are actually some manufacturers that are sending out R-22 units uncharged. They are precharged with nitrogen/helium mix, and need to be charged by weight with R-22. Not sure if this is a loophole around the non manufacture law of 2010 for 22 units or what. Either way, the outside unit will tell the precharge, or nominal operationg charge (if unit is indeed uncharged) on the manufactures label. The charge will be given in oz (ounces). 16 oz to a lbs. NOW, that being said, you must be licensed to work with refrigerants, so I suggest calling in a licensed tech to set the system up. Good luck and please let us know how things work out.