charging split systems

[frankman]

where do i find the formulas for figuring how much refrigerant to add for certain tubing lengths. like if you have a 40 foot lineset 3/4 and 3/8 i need to know how to add exact amount of refrigerant. you measure from the condensing unit to the metering device to determine total length right?

[james10]

You need the manufacturers info on this one as modern splits are critically charged normally xxxgrams per meter for every meter over a certain length

[frankman]

thanks for the info

[martinw58]

the liquid line on modern splits is not a liquid line it is an expansion line so you need the maufactures info for the corect charge