Pounds:
When charging a system there are a few components that need to be accounted for when estimating
the amount of refrigerant needed. The manufacturer of the equipment being charged will provide
specs for the amount of refrigerant to add to the system and the manual should be consulted for
that information.
However, this leaves the liquid and suction lines between the units unaccounted for. The length
of those lines will need to be accounted for to avoid under or over-charging the system.
Refrigerant tank and gauges for charging a residential heat pump
To more accurately approximate the amount of charge needed, add the amount recommended by the
manufacturer with the amount needed for the refrigerant lines.
To calculate the refrigerant needed for the lines, start by noting the size of the liquid and
suction lines.
Then, consult the table below to find the charge weight needed per foot of lines. Note that the
amount of charge will be very different for the liquid and suction lines, and they should be
added together to find the total weight per foot.
Finally, multiply the length of the lines in feet by the weight per foot to find the total
charge needed. Note that you might need to convert from ounces to pounds at this point.
The tables below show the amount of charge needed per foot of line, for various line sizes. Always double-check your charge rates with those recommended or required by the manufacturer of the charge, equipment, and piping in use.