© 1995-2009 Energy Saving Products Ltd.
Troubleshooting the TXV
When issues arise that bring the function of the TXV into
question, factors must be looked into before replacement.
Inspect the TXV for signs of damage. This may be from a
pinched equalizer line to a burnt valve. These issues will
have an adverse affect on the operation of the valve. Should
the equalizer line be pinched, the valve will no longer be
able to supply the proper amount of refrigerant to the coil.
A burnt valve may have an effect on the refrigerant charge
of the TXV bulb or the seal of the valve. This may again
cause an improper amount of refrigerant to be metered by
the valve or cause the valve head to become seized.
The TXV bulb location and mounting should also be
inspected. The bulb should be securely mounted on the
top half of the suction line. If the bulb is loose or on the
lower half of the line, the bulb will not properly sense
the refrigerant temperature and will not meter the proper
amount of refrigerant. Ensure that the bulb is also properly
insulated, as a lack of insulation will expose the bulb to
conditions well outside those of the coil. This will cause an
overfeed of refrigerant to the system.
Should the installation of the valve be proper, and no
damage is evident, inspect the operation of the valve. If
the TXV bulb is removed and held in ones hand, the valve
should react accordingly. This sudden increase in heat will
open the valve. This will cause a rise in suction pressure
and a drop in liquid pressure. Should nothing happen, the
valve is likely seized and will need to be replaced.
Specifications
RPM-E-50
RPM-E-70
RPM-E-100
Matching Fan Coil
HE - 50 / 51 / 52
HE - 70 / 71
HE - 100 / 101
Part Number
20090200050
20090200070
20090200100
Refrigerant Type
R-410A
R-410A
R-410A
TX Cooling MBH
1
18-24
(5.3-7.0 kW)
30-36
(8.8-10.6 kW)
42-60
(12.3-17.6 kW)
Latent Cooling MBH
6.8-8.9
(2.0-2.6 kW)
11.7-13.7
(3.4-4.0 kW)
16.0-22.2
(4.7-6.5 kW)
Fin Material
Aluminum
Aluminum
Aluminum
Tubing Material
Copper
Copper
Copper
Type of Fins
.006 Al
.006 Al
.006 Al
Connection
Sizes
Liquid Line (Lq)
3/8”
(9.5mm)
3/8”
(9.5mm)
3/8”
(9.5mm)
Suction Line (S)
7/8”
(22.3mm)
7/8”
(22.3mm)
7/8”
(22.3mm)
Drain Connection
3/4”
(19mm)
3/4”
(19mm)
3/4”
(19mm)
TXV with Built in Check Valve & Bypass
Yes
Yes
Yes
Site Glass
Yes
Yes
Yes
Access Ports
Yes
Yes
Yes
Freeze Stat
Yes
Yes
Yes
Shipping Weight (lbs)
48
(22kg)
59
(27kg)
74
(34kg)
Module Size (L x W x H)
19
1⁄4
” x 14
5⁄8
” x 18
1⁄2
”
(489mm x 371mm x 470mm)
24
1⁄4
” x 14
5⁄8
” x 18
1⁄2
”
(616mm x 371mm x 470mm)
32” x 14
5⁄8
” x 18
1⁄2
”
(813mm x 371mm x 470mm)
Tons
2
1.5 - 2.0
(5.3 - 7.0 Kw)
2.5 - 3.0
(8.8 - 10.6 Kw)
3.5 - 5.0
(12.3 - 17.6 Kw)
1) Smaller condensers may be matched to the fan coil when needed (match TXV to condenser size)
MBH = Thousand British Thermal Units per Hour TX = Thermal Expansion TXV = Thermal Expansion Valve
2) Minimum of 8 full 2” (51mm) outlets per ton of cooling needed (4 outlets for HE)
and outdoor unit, on and off. This often takes the form of
very short and frequent on cycles. There are many factors
that may contribute to short cycling of the refrigerant
system. These issues can generally be broken down
between airflow related issues, refrigerant issues, and
installation issues.
Low airflow rates are one of the most common causes
of short cycling. As the airflow rate is lowered across the
cooling coil, the coil pressure drops along with it. This lowers
the temperature of the coil and may cause the freeze-stat
to trip. As the system settles, the freeze-stat closes and the
cycle begins again, as the unit does not run long enough
for the space to become adequately conditioned. Ensure
that the proper amount of airflow is provided to the coil.
Check for proper dip-settings and return air practices.
Improperly charged systems run the risk of short cycling
as well. An undercharged system will react much the same
as a system with low airflow. If the charge is low enough, it
may trip out on low pressure. If a system is overcharged, it
may trip out on high head pressure. Ensure that the system
charge is within the bounds described above.
System set-up and installation should be checked
as well. Piping practices should be within the bounds
described above and within the realms of the outdoor unit
manufacturer. Extreme and often unnecessary adjustment
of the TXV can create conditions similar to an undercharged
coil. A poorly placed T-stat, such as underneath a vent, can
cause short cycling. This happens due to the T-stat being
satisfied very shortly after the unit has begun to operate.
Module RPM
Refrigerant Module Installation (RPM-E) (4/4)
Module RPM Refrigerant Module Installation (RPM-E) (4/4)
Short Cycling
Short cycling is the unnecessary running of the indoor
