35
7.2 ELECTRONIC EXPANSION
The RCF EXV equipped coils, cased and uncased, are the first Rheem indoor products to
be produced with the noncommunicating, stand-alone EXV control. One of the biggest
advantages of an EXV is the control can intelligently change the EXV position based on
system demands other than just suction line temperature. By the measurement of the
suction pressure via the vapor line pressure transducer (factory installed) and the vapor
line thermister (field connected to the vapor line, but factory provided within the air han-
dler) the EcoNet™ enabled air handler control calculates the suction superheat at the
indoor coil. This calculation permits the air handler control to make decisions for when to
open and close the electronic expansion valve for the purpose of maintaining a predeter-
mined suction superheat. The electronic valve is equipped with a 4-pole removable exter-
nal stator, and inlet and outlet Chatleff fittings for optimal serviceability. These valves also
have an internal check valve to provide heat pump compatibility. When operating in heat-
ing mode, the air handler control will open the electronic valve completely to permit the
check valve to operate and maximize reverse refrigerant flow.
7.3 EXV VAPOR LINE THERMISTER
IMPORTANT:
DO NOT perform any brazing with the vapor line thermister attached to
any line. After brazing operations have been completed, clamp the vapor line thermister
securely on the vapor line at the 10 to 2 o’clock position with the clip provided on the
thermister. Insulate the vapor line thermister and vapor line with the provided pressure
sensitive insulation (size 4” x 7”) and secure with provided wire ties.
Make sure to protect the EXV pressure transducer, vapor thermister, copper to alu-
minum joint, and service valves from overheating by use of wet rag or some type
of shielding. Double tip torches are not recommended.
IMPORTANT: Vapor line thermister should be located on a horizontal section of
vapor line, just outside of coil box. The copper thermister must never be placed
on any aluminum tube as this will result in galvanic corrosion and eventual failure
of the aluminum tube.
IMPORTANT: Never place the thermister on the heat effected zone near the braze
connection, but it should be located within 6” of the indoor unit.
FIGURE 30
THERMISTER LOCATION
10 O’CLOCK
2 O’CLOCK
VAPOR LINE
THERMISTOR
VAPOR LINE
THERMISTOR
VAPOR LINE
24
17
1
1
⁄
2
Ton
R-410A
* .049
2 TON
* .057
36
17
2
1
⁄
2
Ton
R-410A
* .062
3 TON
* .067
48
21
3
1
⁄
2
Ton
R-410A
* .074
4 Ton
* .078
Indoor
Nominal Capacity
Width
Nominal Tons
Refrigerant
Piston
Summary of Contents for FH2417PTSJSN
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