Electronic Expansion Valve; Filter & Ferrite Rings - Rheem P17 Series Installation Instructions Manual

7.8 Electronic Expansion Valve

(-)P17 heat pumps are equipped with electronic
expansion valves (EXV). The advantage an EXV
is their ability to accurately control refrigerant
flow over a much wider capacity range than a
conventional mechanical TXV can. The Variable
Speed Outdoor Control (VSODC) uses inputs
from the suction line thermistor and suction
pressure transducer to precisely calculate suction
superheat and make necessary adjustments to
the refrigerant flow through the EXV to maintain
the optimum superheat level. The VSODC is
programmed to ignore short duration changes in
the pressure and temperature inputs which allows
more stable operation than conventional TXV's.
The EXV utilizes an external 4-pole removable
7.9 Filter & Ferrite Rings
For the (-)P17 model line there are 3 ferrite
rings and one filter applied on all models. The
ferrite rings are similar in purpose to the choke,
whereas they create an inductive field around
the assembled wires, but they do not filter the
signals. The ferrite rings are applied only for the
purpose of keeping the high voltage lines from
cross contaminating one another and thereby
Filter
Ferrite
Ring
7.0 COMPONENTS & CONTROLS
stator for serviceability. An internal check valve
is provided that assures unrestricted flow in the
reverse direction when the system is operating in
the cooling mode.
creating unexpected operation and electromagnetic
interference. The single filter has been applied to
eliminate high frequency "noise" from the incoming
power line thereby making it more efficient for the
inverter to convert the incoming line voltage single
phase AC power into 3 phase DC power.
Ferrite
Ring
37