Installation Manual - Refrigerant Charge

[cri3541]

Can someone explain this, it is in installation Manual for a 210 ton 30GTN Carrier.

Refrigerant Type: R22
Charge,[/U]Total/Over Clear Glass (lb)
Ckt A 190/40
Ckt B 185/40

Mainly the /40 and /over clear glass (lb)

Never really paid attn. just charged by nameplate and adjusted the proper subcooling and superheat.

Thanks for any replies.

[CCSPIERCE]

Total over clear glass is the amount required to accomplish factory sub cooling. In your example 190 is the factory weigh in charge. If you were not weighing in charge but instead were topping off charge, then you add till a clear sight glass and add the over clear glass amount. Basically it is the same as charging to superheat and subcooling. You can however overcharge the unit using "over clear glass" if the condensor coils are not thoroughly clean (due to coil thickness).

[cri3541]

Thanks for reply, makes sense I did pull out 35 lb's on circuit B on this unit must have been installed by others. The bottom coil was clogged and had very high sub cooling and a high discharged pressure and temp. before cleaning. I cleaned the bottom coils and they looked clean but when you put the water to it tons of dirt came out. As you probaly know this bottom coil is where the subcooling is mostly produced. Just never have paid much attn to the book charge that close on the meaning listed above thanks again.