RA 72 DB / 50 RH , WB = 60 , OA 95 ( hot normal day )
(60 * 3) = 180
180 - 80 - 95 = 5
5 / 2 = 2.5 degree SH ???? I don't think so !!!!! You're gonna have
Trane chart says 2 degrees - go fight with Trane, it is their charging
chart. Under these conditions a small amount of liquid will not hurt,
the hot motor windings will evaporate it!
RA 72 DB / 80 RH , WB = 67 , OA 70 ( cool rainy day, lots of
building leakage )
( 67 * 3) = 201
201 - 80 - 70 = 51
51 / 2 = 25.5 SH ???? I don't think so !!!!! ( this implies running
a MUCH warmer coil, which is the WORST thing to do in this condition !
With an old Trane system, the superheat should be 29 degrees, with a
New 11 SEER Trane system, the superheat should be 22 degrees, with a
Trane packaged system, the superheat should be 28 degrees.
depending on conditions, the superheat will vary from zero degrees to
over 35 degrees. that is actual systems with piston metering device.
If you want constant superheat, install a TXV. That is why a TXV is
better than a piston. For efficiency, dehumidification, comfort!
RA 72 DB / 30 RH , WB = 54 , OA 80 ( warm dry day )
( 54 * 3) = 162
162 - 80 - 80 = 2
2 / 2 = 1 SH ???? I don't think so !!!!!
Old Trane & Packaged Trane = 4 degrees, 11 SEER Trane = zero degrees.
Stop thinking and start measuring.
Get a trane charging slide rule and a Carrier charging slide rule and
see what the equipment manufacturers say. Or start using TXV on all
your jobs and charge by subcooling. This is why I use a lot of Lennox!
They use TXVs on almost everything split.