what is superheat ?

[cfe]

R-134a with spring pressure 9.5 psig =5.5* and evap 30.5 psig =35*
how to calculate the superheat?

[richper]

WHAT??????????????

[JWB]

call a tech. save yourself some money.

[hvacrmedic]

R-134a with spring pressure 9.5 psig =5.5* and evap 30.5 psig =35*
how to calculate the superheat?

Bulb pressure equals spring pressure plus evap outlet pressure, so
P_bulb = 9.5 + 30.5 = 40psig

SH is the bulb saturated temp minus the evap saturated temp (assuming that bulb temp is equal to suction line temp)

From the P/T chart
SH=45-35=10°

[cfe]

Bulb pressure equals spring pressure plus evap outlet pressure, so
P_bulb = 9.5 + 30.5 = 40psig

SH is the bulb saturated temp minus the evap saturated temp (assuming that bulb temp is equal to suction line temp)

From the P/T chart
SH=45-35=10°

thanks hvacmedic.
i thought there is no way to figure out SH with the info provided or just when evap in equilibrium only and maybe cross bulb charge will have different SH reading.

i did the same calculation but end up with 5 SH. i misread 30.5psig to 35.5 psig=40*. 40psig=45*

i always rely on thermometer and gauge to get SH ans SC reading.

[hvacrmedic]

thanks hvacmedic.
i thought there is no way to figure out SH with the info provided or just when evap in equilibrium only.
i did the same calculation but end up with 5 SH. i misread 30.5psig to 35.5 psig=40*. 40psig=45*

i always rely on thermometer and gauge to get SH ans SC reading.

Yes, that was assuming stable operation, and an ideal TXV. Of course no such TXV exists, so this was all correct only on paper.