Type II — High-PressureQuestion 132 of 240
A technician is checking the charge on a system equipped with a thermostatic expansion valve (TXV). Which measurement is the preferred way to verify the charge on a TXV system?
a.Ambient temperature only
b.Superheat at the evaporator inlet
c.Suction pressure alone
d.Subcooling at the condenser outlet (liquid line)
Explanation
On a TXV system, subcooling is the preferred method to check the charge because the valve maintains evaporator superheat fairly constant. Subcooling is the difference between the liquid-line saturation temperature and the actual liquid temperature. Superheat is the main check on fixed-orifice systems rather than TXV systems.
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