Refrigeration/Troubleshooting
Manual
P.O. Box 245
Syracuse, NY 13211
www.roth-america.com
888-266-7684
P/N: 2300100910
Table of Contents:
Section 1: Geothermal Refrigeration
Circuits
Overview................................................................. 2
Water-to-Air Refrigerant Circuit............................ 3
Refrig. Ckt. Component Operation..................... 3
Water-to-Water Refrigerant Circuit...................... 5
Heating Operation................................................. 6
Cooling Operation................................................. 6
Summary................................................................. 8
Section 2: Heat of Extraction/Heat of
Rejection
Overview................................................................. 9
Performance Data................................................. 9
Formulas................................................................ 10
Examples............................................................... 12
Section 3: Superheat/Subcooling
Overview............................................................... 14
Definitions.............................................................. 14
Checking Superheat and Subcooling............... 14
Putting It All Together........................................... 15
Pressure/Temperature Chart R-410A................. 16
Pressure/Temperature Chart R-22...................... 17
Superheat/Subcooling Measurements............. 18
Superheat/Subcooling Tables............................ 19
Examples............................................................... 20
Section 4: Desuperheater Operation
Overview............................................................... 22
Desuperheater Cut-Away................................... 22
Appendix A: Troubleshooting Form
Guide Revision Table:
Date
By
Page
August, 2010
KT
All
Note
First published
Section 1: Geothermal Refrigeration Circuits
Overview
exchanger (water-to-water and waterto-air units) is connected to the ground
loop or open loop (well water) system. The
“load” heat exchanger is connected to the
hydronic load (for example, radiant floor
heating) for water-to-water units. The load
heat exchanger in a water-to-air unit is the
air coil, which is connected to duct work.
Geothermal heat pumps are available in a
variety of configurations to provide flexibility
for installation in new construction or
retrofit applications. Most common in North
America are packaged water-to-air heat
pumps, which provide forced air heating
and cooling. Packaged units (see figure 1)
have the compressor section and the air
handler section in the same cabinet. There
are also other types of geothermal heat
pumps, such as water-to-water, which are
used for radiant floor heating.
Water-to-water heat pumps heat or chill
water instead of heating or cooling the air
(see figure 5). The difference between a
water-to-air and water-to-water heat pump
is the “load” heat exchanger. A second
water-to-refrigerant coil is substituted for
the air to refrigerant coil. The “source” heat
Figure 1: Water-to-Air Refrigeration Circuit
Liquid line (heating)
To suction line bulb
5
Condenser (heating)
Evaporator (cooling)
Liquid line (cooling)
6
To suction line
Filter Drier
TXV
4
Reversing
Valve
Coax
Suction
Discharge
Air Coil
Coax
Suction
Heating
Mode
Air Coil
Air Coil
2
Optional desuperheater
installed in discharge line
(always disconnect during
troubleshooting)
Cooling
Mode
Condenser (cooling)
Evaporator (heating)
Suction
1
3
Discharge
Roth
Source
Coax
Discharge
2
Refrigeration/Troubleshooting Guide,
August, 2010
Section 1: Geothermal Refrigeration Circuits
Water-to-Air Refrigerant Circuit
The water-to-air geothermal heat pump
refrigerant circuit is very simple compared
to air source heat pumps. Defrost cycle
is not required, and all components are
indoors in a single cabinet. The main
components shown in figure 1 are the
compressor (1), the air coil (2), the coaxial
heat exchanger (3), the reversing valve (4),
the TXV or thermal expansion valve (5), and
the filter drier (6).
Compressor: The compressor (1) is the
“heart” of the system. The compressor
pumps refrigerant through the circuit, and
increases the pressure of the refrigerant.
Since pressure and temperature are directly
related, when the pressure is increased, the
temperature is also increased. When the
temperature of the refrigerant is raised to a
higher temperature than the temperature
of the air flowing through the air coil (2)
in heating, heat is released to the air to
heat the building. Likewise, when the
refrigerant temperature is raised to a higher
temperature than the water flowing through
the coaxial heat exchanger (3) in cooling,
heat is released to the water.
1
Roth uses Copeland Scroll compressors.
A scroll is an involute spiral which, when
matched with a mating spiral scroll form
as shown in figure 2, generates a series of
crescent-shaped gas pockets between the
two members. Scroll compressors work by
moving one spiral element inside another
stationary spiral to create a series of gas
pockets that become smaller and increase
the pressure of the gas.
The largest openings are at the outside
of the scroll where the gas enters on the
suction side. As these gas pockets are
closed off by the moving spiral they move
towards the center of the spirals and
become smaller and smaller. This increases
the pressure on the gas until it reaches
the center of the spiral and is discharged
through a port near the center of the scroll.
Both the suction process (outer portion of
the scroll members) and the discharge
process (inner portion) are continuous.
1
1
The moving scroll moves in an orbiting
path within the stationary (fixed) scroll as
it creates the series of gas pockets. During
compression, several pockets are being
compressed simultaneously, resulting in
Figure 2: Scroll Operation
1
Compression in the
scroll is created by the
interaction of an orbiting
spiral and a stationary
spiral. Gas enters the
outer openings as one
of the spirals orbits.
The open passages
are sealed off as gas is
drawn into the spiral.
2
3
Refrigeration/Troubleshooting Guide
August, 2010
2
2
As the spiral continues
to orbit, the gas is
compressed into
two increasingly
smaller pockets.
2
3
3
4
By the time the gas
arrives at the center
port, discharge pressure
has been reached.
3
4
43
5
Actually, during
operation, all six gas
passages are in various
stages of compression
at all times, resulting
in nearly continuous
suction and discharge.
5
Roth
Section 1: Geothermal Refrigeration Circuits
a very smooth process. By maintaining
an even number (six in a Copeland Scroll
compressor) of balanced gas pockets on
opposite sides, the compression forces
inside the scroll work to balance each other
and reduce vibration inside the compressor.
pump to switch from heating to cooling.
The normal (non-energized) mode is
heating. Therefore, the discharge gas from
the compressor flows to the air coil in the
non-energized mode. When the reversing
valve solenoid is energized in cooling, the
valve switches to allow the discharge gas
from the compressor to flow to the coaxial
heat exchanger.
Single speed and two-stage (UltraTech)
scroll compressors are used in Roth’s
product line. The two-stage scroll works
exactly like the single speed scroll shown in
figure 2, but it has additional components,
a solenoid valve, and bypass ports in the
scroll mechanism. When the solenoid valve
opens the bypass ports as shown in figure 3,
the capacity is reduced to 67%, since part
of the scroll is bypassed.
The reversing valve is a pilot-operated
valve, which means that the solenoid
opens a small port, connecting the
copper tubing from the bottom port
(discharge line from the compressor) to the
valve chamber. The high pressure of the
discharge line forces the valve to switch
from one mode to the other.
Figure 3: UltraTech Operation
67% - Ports Open
Thermal Expansion Valve (TXV): The TXV (5)
“meters” refrigerant to make sure that the
proper amount of refrigerant is being fed to
the heat exchangers in order to maximize
the condensing and evaporating functions.
The TXV is also important in keeping liquid
refrigerant from reaching the suction line of
the compressor, which could damage the
compressor. The TXV is designed to operate
bi-directionally in packaged water-to-air
and water-to-water heat pumps.
100% Ports Closed
Air Coil: The air coil (2), a refrigerant-to-air
heat exchanger servers as the condenser in
heating, and the evaporator in cooling.
Figure 4: TXV Operation
Coaxial Heat Exchanger: The coaxial heat
exchanger (3), a water-to-refrigerant heat
exchanger, serves as the evaporator in
heating, and the condenser in cooling.
Diaphram
Reversing Valve: The reversing valve (4)
provides the ability to switch functions
of the two heat exchangers, above. As
shown in figure 1, the discharge line from
the compressor is always connected to the
bottom of the reversing valve. The center
connection at the top is always connected
to the suction line from the compressor.
The other two connections allow the heat
Roth
Valve Seat
4
Pin
4
4
= Liquid Pressure
(opening force)
Refrigeration/Troubleshooting Guide,
August, 2010
Section 1: Geothermal Refrigeration Circuits
Figure 4 shows the operation of the TXV, and
the four forces that affect the operation.
The TXV has two copper fittings for
connection to the air coil and coaxial heat
exchanger, as well as two smaller copper
lines that are used for metering. One line
is connected to a bulb that is attached to
the suction line of the compressor. The bulb
is filled with refrigerant. As the suction line
temperature changes, the bulb pressure
changes. The other line is connected
directly to the suction line. The bulb pressure
(force 1) pushes down on the diaphragm
as the bulb pressure increases (suction line
temperature increases). When the pressure
pushes down on the diaphragm, the pin
(which is attached to the diaphragm) is
pushed away from the valve seat, which
opens the valve.
the valve. This relationship of temperature
(bulb pressure) and pressure (suction line)
creates a balancing effect, which causes
the valve to meter at 0°F superheat (see
section 3 for explanation of superheat).
Since it is important to make sure that liquid
is not returning to the compressor, the valve
spring (force 3) is adjusted to “fool” the
valve into balancing at a higher superheat
(usually 10 to 12°F). Force 4 (liquid pressure)
is an opening force.
Filter Drier: The filter drier (6) functions
exactly as its name implies. It filters any
particles from the refrigerant system,
and it pulls moisture from the system. It is
extremely important that the filter drier is
changed any time the refrigerant circuit
is open for a component replacement or
repair, especially for systems with R-410A
refrigerant. R-410A uses P.O.E. oil, which
is hygroscopic (tendency of a material
to absorb moisture from the air). Moisture
contaminates the refrigerant circuit over
time, and must be avoided.
The other line, connected directly to the
suction line uses suction pressure (force 2) to
push up on the diaphragm as the pressure
increases. As the diaphragm is pushed up,
the pin is pushed into the valve seat, closing
Figure 5: Water-to-Water Refrigerant Circuit
Condenser (heating)
Evaporator (cooling)
Liquid line (heating)
To suction line bulb
Liquid line (cooling)
To suction line
Filter Drier
TXV
Load
Coax
Reversing
Valve
Source Coax
Suction
Load Coax
Source Coax
Suction
Heating
Mode
Load Coax
Discharge
Optional desuperheater
installed in discharge line
(always disconnect during
troubleshooting)
Cooling
Mode
Condenser (cooling)
Evaporator (heating)
Suction
Source
Coax
Discharge
Discharge
Refrigeration/Troubleshooting Guide
August, 2010
5
Roth
Section 1: Geothermal Refrigeration Circuits
Water-to-Water Refrigerant Circuit
pressure and temperature are directly
related, so the temperature also drops after
the TXV. At this point, the refrigerant is a
low temperature liquid (typically 15 to 50°F,
depending upon loop temperature).
The water-to-water heat pump refrigerant
circuit, as shown in figure 5, functions
exactly the same as the the water-to-air
refrigerant circuit with one exception. The
air coil is replaced by a second coaxial
heat exchanger. The source coax is
the same as the water-to-air unit coax.
However, the load coax heats or chills
water instead of heating or cooling the air.
The warm water (or water/antifreeze
solution) flowing through the coaxial heat
exchanger (typically 30 to 60°F) causes the
cold refrigerant to “boil” off (evaporate)
into a gas or vapor. Thus, the coax is the
evaporator in heating.
Heating Operation
After leaving the coax (evaporator), the
refrigerant is now approximately the same
temperature as the water entering the
heat pump. This low pressure gas enters the
compressor, and the cycle starts all
over again.
For the purposes of discussing the refrigerant
circuit operation in heating and cooling
modes, the water-to-air circuit will be used.
The other configurations directly apply with
minor terminology/component changes.
Proper refrigerant metering will insure that
no liquid is returned to the compressor.
Section 3 discusses superheat and
subcooling, which allow the technician
to evaluate how well the condenser and
evaporator are operating.
In heating mode (see figure 7), the
reversing valve is not energized. The high
temperature, high pressure refrigerant gas
from the compressor flows to the air coil. As
the air moves through the air coil, the cool
(typically 70°F) air causes the hot refrigerant
(typically 130 to 180°F) to condense into a
liquid. Thus, the air coil is the condenser in
the heating mode.
Cooling Operation
In cooling mode (see figure 8), the
reversing valve must be energized. The high
temperature, high pressure refrigerant gas
from the compressor flows to the coaxial
heat exchanger. As the water (or water/
antifreeze solution) flows through the coax,
the cool (typically 50 to 100°F) water causes
the hot refrigerant (typically 130 to 180°F) to
condense into a liquid. Thus, the coax is the
condenser in the cooling mode.
After leaving the air coil (condenser),
the refrigerant is approximately the
temperature of the leaving air. The
refrigerant is within a few psi of being at the
same pressure as it was at the compressor
discharge line. This is the heating liquid line.
The liquid line of a packaged unit changes
location, depending upon the mode of
operation. It is always located between
the TXV and the condenser. However,
since a geothermal unit is a heat pump,
the condenser can either be the air coil
(heating) or coaxial water coil (cooling).
After leaving the coax (condenser),
the refrigerant is approximately the
temperature of the water leaving the
coax. The refrigerant is within a few psi of
the compressor discharge line pressure.
This is the cooling liquid line. The liquid line
of a packaged unit changes location,
At the TXV, the refrigerant is forced through
a very small opening, which causes a
large pressure drop. As mentioned earlier,
Roth
6
Refrigeration/Troubleshooting Guide,
August, 2010
Section 1: Geothermal Refrigeration Circuits
Figure 7: Heating Mode
Liquid line (heating)
To suction line bulb
Condenser (heating)
Evaporator (cooling)
Liquid line (cooling)
To suction line
Filter Drier
TXV
Air Coil
Reversing
Valve
Discharge
Optional desuperheater
installed in discharge line
(always disconnect during
troubleshooting)
Condenser (cooling)
Evaporator (heating)
Suction
Source
Coax
Figure 8: Cooling Mode
Liquid line (heating)
To suction line bulb
Condenser (heating)
Evaporator (cooling)
Liquid line (cooling)
To suction line
Filter Drier
Air Coil
TXV
Reversing
Valve
Discharge
Optional desuperheater
installed in discharge line
(always disconnect during
troubleshooting)
Condenser (cooling)
Evaporator (heating)
Suction
Source
Coax
Refrigeration/Troubleshooting Guide
August, 2010
7
Roth
Section 1: Geothermal Refrigeration Circuits
depending upon the mode of operation. It
is always located between the TXV and the
condenser. However, since a geothermal
unit is a heat pump, the condenser can
either be the air coil (heating) or coaxial
water coil (cooling).
condenser in cooling and the evaporator in
heating. Water-to-water units use a second
coax instead of the air coil.
The reversing valve is energized in the cooling
mode. The non-energized mode is heating.
At the TXV, the refrigerant is forced through
a very small opening, which causes a large
pressure drop. Once again, since pressure
and temperature are directly related, the
temperature also drops after the TXV. At this
point, the refrigerant is a low temperature
liquid (typically 35 to 45°F, depending upon
return air temperature and air flow).
The warm air flowing through the air coil
(typically 70 to 80°F) causes the cold
refrigerant to “boil” off (evaporate) into
a gas or vapor. Thus, the air coil is the
evaporator in cooling.
After leaving the air coil (evaporator), the
refrigerant is now approximately the same
temperature as the air entering the heat
pump. This low pressure gas enters the
compressor, and the cycle starts all
over again.
Summary
To summarize, refrigerant circuits in
geothermal heat pumps can be configured
for packaged water-to-air, water-to-water,
split systems or combination water-to-air
and water-to-water units. All circuits utilize
a Copeland scroll (single or two-stage)
compressor, one or two water-to-refrigerant
coaxial coils, an air-to-refrigerant coil, a
reversing valve, a bi-directional TXV, and
a filter drier. Combination units include a
direction valve and a 3-way valve to switch
condenser operation.
The air coil operates as the condenser in
heating, and the evaporator in cooling.
The source (loop) coax operates as the
Roth
8
Refrigeration/Troubleshooting Guide,
August, 2010
Section 2: Heat of Extraction/Heat of Rejection
Overview
indicate HE and HR. In figure 9, HE is the
amount of heat that is being extracted
As mentioned in section 1, most geothermal from the water (for example, ground loop)
by the refrigerant circuit. The compressor
heat pumps are packaged water-to-air
and fan power (kW column) is used to
heat pumps. Therefore, the refrigerant
operate the refrigerant circuit. The heat
circuit is evacuated and charged at the
delivered to the space (HC column) equals
factory, and there is no need to connect
the HE from the water plus the waste heat
refrigerant gauges unless the technician
of the power used for compressor and fan.
has verified that there is a refrigerant
If the kW is converted to Btuh, and added
circuit problem. Since connecting gauges
to the HE, the sum should equal HC.
can cause a loss of charge and affect
performance, Roth recommends against
For example, in figure 9, at 30°F EWT, 9.0
connecting refrigerant gauges at startup.
GPM and 70°F EAT, the heating capacity
There are a number of checks that can
is 30,700 Btuh. HE is 21,800 Btuh. If the kW
be made at startup to verify performance
(2.63) is converted to Btuh (2.63 x 3.412 =
without connecting refrigerant gauges.
8.97 MBtuh or 8,970 Btuh), and added to
Heat of extraction is a calculation of the
HE, the result is HC. Therefore, if HE is within,
amount of heat that is being “extracted” or 10-15% of catalog performance, HC should
“absorbed” from the water or water/antialso be within specifications. There is no
freeze solution by the evaporator (coaxial
need to connect refrigerant gauges if HE is
heat exchanger) in the heating mode.
within specifications.
Heat of rejection is the amount of heat
that is being “rejected” to the water by the In figure 10, HR is the amount of heat that is
condenser (coaxial heat exchanger) in the being rejected to the water (for example,
cooling mode. In addition to measuring the ground loop) by the refrigerant circuit. The
temperature rise or drop across the air coil, compressor and fan power (kW column) is
used to operate the refrigerant circuit. The
calculating heat of extraction or heat of
rejection allows the technician to verify that heat rejected from the space (HR column)
equals the heat from the air (TC column -the heat pump is performing according to
amount of cooling) plus the waste heat of
specifications. If the calculation shows that
the power used for compressor and fan. If
the heat pump is performing poorly, then
the kW is converted to Btuh, and added to
refrigeration gauges may be required to
the TC, the sum should equal HR.
further troubleshoot the problem.
Performance Data
For example, in figure 10, at 90°F EWT, 9.0
GPM and 75°F DB/63°F WB (50% RH), HR
is 43,400 Btuh. TC is 34,400 Btuh. If the kW
(2.73) is converted to Btuh (2.73 x 3.412 =
9.31 MBtuh or 9310 Btuh), and added to
TC, the result is HR. Thefore, if HR is within,
10-15% of catalog performance, TC should
also be within specifications. There is no
need to connect refrigerant gauges if HR is
within specifications.
Before discussing heat of extraction (HE)
/ heat of rejection (HR) calculations, the
technician should understand how to use
the performance data in the catalog to
compare the unit specifications to actual
calculations.
Figures 9 and 10 show performance data
for a typical 3 ton geothermal water-toair heat pump. the highlighted columns
Refrigeration/Troubleshooting Guide
August, 2010
9
Roth
Formulas
water pressure drop values and three water
flow rates. At 50°F, if the pressure drop is 1.7
psi, the flow rate would be 5.0 GPM; if the
pressure drop is 3.1 psi, the flow rate would
be 7.0 GPM; and if the pressure drop is 5.0
psi, the flow rate would be 9.0 GPM. The flow
rate in this example is 9.0 GPM. Rarely are
the temperature and pressure drop exactly
as shown in the tables, so there will be some
interpolation required (for example, 52°F EWT
and 4.7 psi pressure drop).
The formula is the same for HE and HR.
The amount of heat being extracted
or rejected can be calculated if the
temperature difference between water
entering and leaving the coaxial heat
exchanger (TD) is known, and the water
flow (GPM) is measured. The only other item
needed is the type of antifreeze. A fluid
factor is used to represent the specific heat
of the water/antifreeze solution, as well as
to convert the units (GPM and °F) to Btuh.
NOTE: A large gauge face is preferred,
since it will be easier to read pressures to
the nearest 0.5 psi. ALWAYS use the same
gauge in the “IN” and “OUT” connections.
The use of two gauges could cause false
readings, since they could both be out of
calibration in opposite directions. Never
force the gauge adapter into the P/T port.
The gauge adapter could break off in the
P/T port, or the force could cause the ring
holding the P/T port bladder to become
dislodged, potentially ending up in a
pump impeller.
HE or HR (Btuh) = GPM x TD x Fluid Factor
Where: GPM = Flow rate in U.S. gallons per
minute TD = Temp. diff. (between water in
& out) Fluid Factor = 500 for water; 485 for
most antifreezes
Figures 11 and 12 show the tools required
for checking HE and HR. All technicians
installing and servicing geothermal heat
pumps should have at least one set of
these tools.
Flow rate can be determined by measuring
the pressure drop across the coaxial heat
exchanger. The pressure gauge and adapter
should be inserted into the P/T (pressure/
temperature) port of the “Water IN”
connection. Record the reading. Next, insert
the gauge into the “Water OUT” port, and
record the reading. The difference between
the “IN” and “OUT” is the pressure drop.
Once the pressure drop of the heat
exchanger is known, the flow rate can be
determined by consulting the performance
data for the particular unit.
Example:
In heating mode, model 036 has EWT of
50°F, water pressure “IN” of 40 psi, and water
pressure “OUT” of 35 psi. The pressure drop,
therefore is 5 psi. Figure 10 shows three
Roth
Once the flow rate is determined, the
pocket thermometer can be used to obtain
TD. Insert the thermometer into the “Water
IN” P/T port. Record the temperature. Insert
the thermometer into the “Water OUT”
port, and record the temperature. The
difference between the “IN” and “OUT”
is the TD. In heating, EWT (entering water
temperature) will be warmer than LWT
(leaving water temperature); in cooling it
will be just the opposite.
The last item needed is the type of fluid
circulating through the heat pump. As
mentioned earlier, 500 should be used for
pure water (open loop/well water systems).
Use 485 for most antifreeze solutions (see
Flow Center and Loop Application Manual
for details on antifreeze solutions).
10
Refrigeration/Troubleshooting Guide,
August, 2010
Section 2: Heat of Extraction/Heat of Rejection
Figure 9: Typical Performance Data - Heating Mode
Entering
Flow
Water
Entering
Heat of
Leaving Coefficient
Water
Rate
Press. Drop
Air
Extraction
Air
of
Temp (°F) (U.S. GPM) (PSI & Ft. of Head) Temp (°F) (MBtuh) Temp (°F) Performance
Desuperheater
Heating
036 Performance Data:
Capacity
Input
Capacity
3.0 Ton, 1200 CFM, Heating
(MBtuh)
Power
(kW)
(MBtuh)
EWT
GPM
5.0
30
7.0
9.0
5.0
50
7.0
9.0
WPD
Heating
PSI
FT
1.8
4.2
3.4
7.8
5.4
12.5
1.7
3.9
3.1
7.2
5.0
11.6
Heating with Desuperheater
EAT
HC
HE
LAT
KW
COP
HC
HE
LAT
KW
DH
60
30.2
21.7
83.3
2.47
3.58
26.5
21.7
80.4
2.45
3.8
COP
3.62
70
29.4
20.4
92.7
2.61
3.30
25.5
20.5
89.7
2.56
3.9
3.36
80
28.4
19.2
101.9
2.73
3.05
24.4
19.3
98.9
2.68
4.0
3.11
60
31.1
22.6
84.0
2.50
3.65
27.3
22.7
81.0
2.45
3.9
3.73
70
30.3
21.3
93.4
2.63
3.37
26.3
21.4
90.3
2.58
4.0
3.44
80
29.4
20.0
102.7
2.77
3.12
25.3
20.1
99.5
2.7
4.1
3.19
60
31.5
23.0
84.3
2.50
3.70
27.6
23.2
81.3
2.44
3.9
3.78
70
30.7
21.8
93.7
2.63
3.42
26.6
18.7
90.6
2.58
4.1
3.49
80
29.9
20.4
103.1
2.76
3.17
25.7
20.5
99.8
2.71
4.2
3.23
60
39.1
30.3
90.2
2.59
4.42
34.2
30.6
86.4
2.51
4.9
4.57
70
37.9
28.5
99.3
2.73
4.07
32.9
28.8
95.4
2.65
5.0
4.20
80
36.6
26.8
108.3
2.86
3.75
31.5
27.1
104.3
2.78
5.1
3.86
4.67
60
40.7
31.7
91.4
2.64
4.52
35.7
32.1
87.5
2.56
5.1
70
39.4
30.0
100.4
2.78
4.15
34.2
30.2
96.4
2.69
5.2
4.29
80
38.1
28.1
109.4
2.93
3.82
32.8
28.4
105.3
2.83
5.4
3.95
60
41.6
32.6
92.1
2.65
4.59
36.4
32.8
88.1
2.56
5.2
4.76
70
40.2
30.7
101.1
2.79
4.22
34.9
31.1
96.9
2.70
5.3
4.36
80
38.9
28.9
110
2.94
3.88
33.4
29.2
105.8
2.84
5.5
4.01
Figure 10: Typical Performance Data - Cooling Mode
Total Cooling, (MBtuh)
= SC + LC (Latent Cap)
Sensible Cooling Heat of
(MBtuh)
Rejection
(MBtuh)
Input
Power (kW)
Energy
Efficiency
Ratio
036 Performance Data:
3.0 Ton, 1200 CFM, Cooling
EWT
GPM
5.0
70
7.0
9.0
5.0
90
7.0
9.0
WPD
PSI
1.7
3.0
4.8
1.6
2.8
4.5
FT
3.9
6.9
11.1
3.6
6.4
10.3
EAT
DB/
WB
Cooling
Cooling with Desuperheater
TC
SC
HR
KW
EER
TC
SC
HR
KW
DH
75/63
36.7
26.8
44.8
2.41
15.2
36.9
26.9
44.9
2.35
4.7
15.7
80/67
39.8
27.9
47.6
2.47
16.1
40.0
28.0
47.7
2.40
4.9
16.7
EER
85/71
43.0
29.0
50.5
2.51
17.2
43.3
29.1
50.6
2.46
5.1
17.6
75/63
37.2
27.1
45.0
2.29
16.2
37.4
27.2
45.1
2.26
4.6
16.6
80/67
40.5
28.2
47.9
2.34
17.3
40.4
28.3
48.0
2.31
4.7
17.6
85/71
43.7
29.3
50.8
2.39
18.3
43.9
29.5
50.9
2.34
4.8
18.7
75/63
37.6
27.1
45.2
2.22
16.9
37.8
27.2
45.4
2.21
4.3
17.1
80/67
40.9
28.2
48.1
2.27
18.0
41.1
28.3
48.3
2.26
4.5
18.2
19.3
85/71
44.1
29.3
50.9
2.32
19.0
44.3
29.5
51.2
2.30
4.7
75/63
33.4
25.7
43.1
2.98
11.2
33.7
25.9
43.3
2.89
6.3
11.7
80/67
36.3
26.8
45.9
3.04
11.9
36.6
27.0
46.0
2.95
6.4
12.4
85/71
39.2
27.9
48.7
3.09
12.7
39.5
28.0
48.8
3.01
6.6
13.2
75/63
34.0
26.0
43.4
2.81
12.1
34.3
26.2
43.6
2.75
6.0
12.5
80/67
37.0
27.1
46.1
2.87
12.9
37.3
27.2
46.3
2.80
6.2
13.3
85/71
40.0
28.1
48.8
2.92
13.7
40.4
28.3
49.2
2.87
6.3
14.1
75/63
34.4
26.0
43.4
2.73
12.6
34.7
26.2
43.8
2.70
5.8
12.9
80/67
37.4
27.1
46.2
2.78
13.4
37.8
27.2
46.6
2.75
5.9
13.7
85/71
40.4
28.1
49.0
2.85
14.2
40.8
28.3
49.4
2.80
6.1
14.5
Refrigeration/Troubleshooting Guide
August, 2010
11
Roth
Section 2: Heat of Extraction/Heat of Rejection
Figure 13 includes an example water-to-air
heat pump in heating mode; figure 14 shows
the same heat pump in cooling. Following
are two examples based upon these figures,
which are shown on the next page.
performing better than specifications.
Example 1: Model 036, ground loop system
with ProCool (ethanol) antifreeze solution,
heating mode.
1) Fluid factor = 485
2) EWT = 90.0°F LWT = 101.2°F TD = 11.2°F
3) Pressure “IN” = 40 psi
Pressure “OUT” = 36.3 psi
Pressure drop = 3.7 psi
From performance data, GPM = 8.0
4) HR = GPM x TD x Fluid Factor
HR = 8.0 x 11.2 x 485 = 43,456 Btuh
1) Fluid factor = 485
2) EWT = 30.0°F LWT = 23.5°F TD = 6.5°F
3) Pressure “IN” = 40 psi
Pressure “OUT” = 36.6 psi
Pressure drop = 3.4 psi
From performance data, GPM = 7.0
4) HE = GPM x TD x Fluid Factor
HE = 7.0 x 6.5 x 485 = 22,067 Btuh
Catalog HE = 21,300 Btuh. Therefore, unit is
Example 2: Model 036, ground loop system
with ProCool (ethanol) antifreeze solution,
cooling mode.
Catalog HR = 43,400 Btuh. Therefore, unit is
performing better than specifications.
NOTE: HE and HR should be within 10-15% of
catalog values.
Figure 11: Pressure Gauge with Adapter
Gauge Adapter
(P/N TSPTN)
Adapter
Protector
Pressure Gauge
(P/N TSPG-GC or equivalent)
Figure 12: Pocket Thermometer
Pocket Thermometer
P/N TSDT or equivalent
Roth
12
Refrigeration/Troubleshooting Guide,
August, 2010
Section 2: Heat of Extraction/Heat of Rejection
Figure 13: Heating Operation Example
°F
psi
°F
Liquid line (heating)
Load IN
GPM
To suction line bulb
°F
Liquid line (cooling)
To suction line
Filter Drier
TXV
For water-to-water units
substitute a second coaxial
heat exchanger for the air coil.
Air Coil
Load
Coax
°F
psi
psi
°F
Suction Line (saturation)
°F
Suction temp
Reversing
Valve
psi
°F
Discharge Line (saturation)
30.0 °F
Load OUT
93.4 °F
70.0 °F
Coax
Suction
Coax
Suction
Air Coil
Heating
Mode
Air Coil
Supply Air
Return Air
40.0
Optional desuperheater
installed in discharge line
(always disconnect during
troubleshooting)
psi
Source (loop) IN
Cooling
Mode
Source
Coax
GPM
Discharge
Discharge
23.5 °F
36.6
psi
Source (loop) OUT
Figure 14: Cooling Operation Example
°F
psi
°F
Liquid line (heating)
Load IN
GPM
To suction line bulb
°F
Liquid line (cooling)
To suction line
Filter Drier
TXV
For water-to-water units
substitute a second coaxial
heat exchanger for the air coil.
Air Coil
Load
Coax
°F
psi
psi
°F
Suction Line (saturation)
°F
Suction temp
Reversing
Valve
psi
°F
Discharge Line (saturation)
90.0 °F
Load OUT
55.0 °F
75.0 °F
Coax
Suction
Coax
Suction
Air Coil
Heating
Mode
Air Coil
Supply Air
Return Air
40.0
Optional desuperheater
installed in discharge line
(always disconnect during
troubleshooting)
Cooling
Mode
GPM
Discharge
psi
Source (loop) IN
Source
Coax
Discharge
101.2 °F
36.3
psi
Source (loop) OUT
Refrigeration/Troubleshooting Guide
August, 2010
13
Roth
Section 3: Superheat/Subcooling
Overview
Superheat and subcooling are used to
determine if the heat pump has the proper
refrigerant charge, as well as for verifying
that the condenser and evaporator
are performing properly. Superheat
and subcooling can even be used to
troubleshoot refrigerant circuit blockages or
a bad TXV.
Definitions
Saturation Temperature: Saturation
temperature, sometimes called boiling
point, is the temperature at which a
refrigerant changes state. For example,
Table 1 shows that refrigerant R-410A has
a saturation temperature of 32°F at 100
psi. Therefore, the refrigerant at 100 psi is a
liquid if it is below 32°F, and a gas (vapor) if
it is above 32°F.
Superheat: Superheat is defined as the
number of degrees above the saturation
temperature of a refrigerant. For example,
if the temperature of refrigerant R-410A is
40°F at 100 psi, it has 8°F of superheat, since
the saturation temperature is 32°F.
Subcooling: Subcooling is defined as the
number of degrees below the saturation
temperature of a refrigerant. For example,
if the temperature of refrigerant R-410A
is 28°F at 100 psi, it has 4°F of subcooling,
since the saturation temperature is 32°F.
Checking Superheat and Subcooling
Superheat and subcooling should only be
checked after the heat of extraction or
heat of rejection calculations (see section
2) indicate that the unit is performing
poorly. Connecting refrigerant gauges
should be done as a last resort.
Roth
Checking superheat and subcooling requires
a refrigeration gauge set with manifold and
hoses, plus a digital thermocouple type
thermometer. Heat pumps produced by
Roth have two schrader ports for service
connections, one at the discharge line of
the compressor, and one at the suction line
of the compressor. When these pressures
are used in conjunction with the suction line
temperature and liquid line temperature,
superheat and subcooling can be
calculated. Insulation should be removed
from the suction line and liquid line, and the
copper should be free from insulation glue,
so that the thermocouple makes a good
connection at the copper line.
Figures 15a and 15b illustrate the locations
for taking pressure and temperature
measurements. Notice that the two areas
for temperature measurement are suction
line and liquid line. In order to check
superheat and subcooling, the saturation
temperature must be determined, which
requires the pressure of the refrigerant and
the actual temperature of the refrigerant
at the same location. However, the only
location where both temperature and
pressure are easily obtained is at the
suction line. In section 1, temperatures
and pressures were discussed in relation
to components, both before and after
the components. It was also mentioned
that the discharge pressure and the
liquid line pressure are within a few psi
of each other. Most manufacturers of
packaged equipment adjust their service
data to allow the technician to use the
discharge pressure as the liquid line
pressure. Therefore, for checking superheat
and subcooling, use discharge pressure
with liquid line temperature, and suction
pressure with suction temperature.
Although superheat and subcooling can
be calculated anywhere in the refrigeration
14
Refrigeration/Troubleshooting Guide,
August, 2010
Section 3: Superheat/Subcooling
circuit, there are two points that are most
useful for troubleshooting purposes. First of
all, it is imperative that liquid is not returned
to the compressor. Liquid refrigerant
will “wash” some of the compressor oil
away from critical internal parts, causing
premature compressor failure. Plus, the
compressor is designed to pump gas, not
liquid, and will be operating under adverse
conditions. Checking for superheat at the
suction line of the compressor insures that
the state of the refrigerant at this point is
a gas (vapor). The amount of superheat
at the suction line determines how well
the evaporator (coax in heating, air coil in
cooling) is working. Superheat is normally
in the 8 to 12°F range, but the installation
manual will provide specific information for
the unit being serviced. NOTE: Check the
temperature of the suction line near the
TXV bulb, especially on split systems.
is overcharged. If subcooling is measured,
the high value would indicate that there
is a problem with the refrigeration charge.
Table 3 lists the conditions associated with
high or low superheat and subcooling.
Table 4 is an example of typical data found
in the installation manual.
Figures 16 through 18 illustrate examples
of a normally charged system, an
undercharged system, and an
overcharged system.
The other location to check is the liquid
line. Since the liquid line is located after
the condenser (air coil in heating, coax
in heating), the amount of subcooling
determines how well the condenser is
working. In most cases subcooling is in the
4 to 10°F range, but the installation manual
will provide specific information for the unit
being serviced.
Putting It All Together
In section 1, TXV operation was discussed.
Since the TXV spring has been adjusted
to maintain 8 to 12°F of superheat, it will
close down when necessary to maintain
the predetermined superheat setting.
Therefore, subcooling plays a crucial part in
evaluating the unit’s refrigeration charge. In
other words, if the unit is overcharged, the
TXV will close down to maintain superheat,
backing up liquid refrigerant in the
condenser. If only superheat is measured,
the technician would not know that the unit
Refrigeration/Troubleshooting Guide
August, 2010
15
Roth
Section 3: Superheat/Subcooling
Table 1: Pressure/Temperature Chart, R-410A Refrigerant
Pressure
PSIG
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50
52
54
56
58
60
62
64
66
68
70
72
74
76
78
80
85
90
95
100
105
110
115
120
Roth
Saturation
Temp (°F)
R-410A
-60
-58
-54
-50
-46
-42
-39
-36
-33
-30
-28
-26
-24
-20
-18
-16
-14
-12
-10
-8
-6
-4
-3
-2
0
1
3
4
6
7
8
10
11
13
14
15
16
17
19
20
21
24
26
29
32
34
36
39
41
Pressure
PSIG
125
130
135
140
145
150
155
160
165
170
175
180
185
190
195
200
205
210
215
220
225
230
235
240
245
250
255
260
265
270
275
280
285
290
295
300
305
310
315
320
325
330
335
340
345
350
355
360
365
Saturation
Temp (°F)
R-410A
43
45
47
49
51
53
55
57
59
60
62
64
66
67
69
70
72
73
75
76
78
79
80
82
83
84
85
87
88
89
90
91
92
94
95
96
97
98
99
100
101
102
104
105
106
108
108
109
110
Pressure
PSIG
370
375
380
385
390
395
400
405
410
415
420
425
430
435
440
445
450
455
460
465
470
475
480
485
490
495
500
505
510
515
520
525
530
535
540
545
550
555
560
565
570
575
580
585
590
595
600
650
700
16
Saturation
Temp (°F)
R-410A
111
112
113
114
115
116
117
118
119
120
121
122
122
123
124
125
126
127
128
129
130
130
131
132
133
134
134
135
136
137
138
138
139
140
141
142
142
143
144
145
146
146
147
148
149
149
149
154
159
Refrigeration/Troubleshooting Guide,
August, 2010
Section 3: Superheat/Subcooling
Table 2: Pressure/Temperature Chart, R-22 Refrigerant
Pressure
PSIG
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50
52
54
56
58
60
62
64
66
68
70
72
74
76
78
80
85
Saturation
Temp (°F)
R-22
-41
-37
-32
-28
-24
-20
-17
-14
-11
-8
-5
-3
0
2
5
7
9
11
13
15
17
19
21
23
24
26
28
29
31
32
34
35
37
38
40
41
42
44
45
46
48
51
Pressure
PSIG
90
95
100
105
110
115
120
125
130
135
140
145
150
155
160
165
170
175
180
185
190
195
200
205
210
215
220
225
230
235
240
245
250
255
260
265
270
275
280
285
290
295
Saturation
Temp (°F)
R-22
54
56
59
62
64
67
69
72
74
76
78
81
83
85
87
89
91
93
94
96
98
100
101
103
105
107
108
110
112
113
115
116
118
119
120
121
123
124
126
127
129
130
Refrigeration/Troubleshooting Guide
August, 2010
Pressure
PSIG
300
305
310
315
320
325
330
335
340
345
350
355
360
365
370
375
380
385
390
395
400
405
410
415
420
425
430
435
440
445
450
455
460
465
470
475
480
485
490
495
500
17
Saturation
Temp (°F)
R-22
132
133
134
135
136
137
138
140
141
142
144
144
145
146
147
148
149
151
152
153
155
155
156
158
159
160
160
161
162
163
164
165
167
168
169
169
170
171
172
173
173
Roth
Section 3: Superheat/Subcooling
Figure 15a: Superheat/Subcooling Measurement - Heating
°F
psi
°F
Liquid line (heating)
Load IN
GPM
1
Suction
°F
Liquid line (cooling)
To suction line bulb
To suction line
Discharge
R-410A Manifold/Gauge Set
Filter Drier
TXV
2
For water-to-water units
substitute a second coaxial
heat exchanger for the air coil.
Air Coil
Load
Coax
°F
psi
psi
°F
Suction Line (saturation)
°F
Suction temp
Reversing
Valve
°F
psi
Discharge Line (saturation)
°F
Load OUT
°F
Supply Air
°F
Return Air
psi
Optional desuperheater
installed in discharge line
(always disconnect during
troubleshooting)
Source (loop) IN
Thermometer
°F
1
Source
Coax
GPM
2
°F
psi
Source (loop) OUT
Figure 15b: Superheat/Subcooling Measurement - Cooling
°F
psi
°F
Liquid line (heating)
Load IN
GPM
Suction
°F
Liquid line (cooling)
To suction line bulb
To suction line
R-410A Manifold/Gauge Set
1
Filter Drier
TXV
2
Air Coil
Load
Coax
For water-to-water units
substitute a second coaxial
heat exchanger for the air coil.
°F
psi
Discharge
psi
°F
Suction Line (saturation)
°F
Suction temp
Reversing
Valve
psi
°F
Discharge Line (saturation)
°F
Load OUT
°F
Return Air
°F
Supply Air
Optional desuperheater
installed in discharge line
(always disconnect during
troubleshooting)
psi
Source (loop) IN
Thermometer
°F
1
GPM
Source
Coax
2
°F
psi
Source (loop) OUT
Roth
18
Refrigeration/Troubleshooting Guide,
August, 2010
Section 3: Superheat/Subcooling
Table 3: Superheat/Subcooling Conditions
Superheat Subcooling
Condition
Normal
Normal
Normal operation
Normal
High
Overcharged
High
Low
Undercharged
High
High
Restriction or TXV is stuck almost closed
Low
Low
TXV is stuck open
Table 4: Typical R-410A Unit Superheat/Subcooling Values
EWT
GPM
Per Ton
30
1.5
3
1.5
3
1.5
3
50
70
EWT
GPM
Per Ton
50
1.5
3
1.5
3
70
Discharge
Pressure
(PSIG)
285-310
290-315
315-345
320-350
355-395
360-390
Suction
Pressure
(PSIG)
68-76
70-80
100-110
105-115
135-145
140-150
Heating - Without Desuperheater
Sub
Super
Air
Cooling
Heat
Temperature
Rise (°F-DB)
4-10
8-12
14-20
4-10
8-12
16-22
6-12
9-14
22-28
6-12
9-14
24-30
7-12
10-15
30-36
7-12
10-15
32-38
Water
Temperature
Drop (°F)
5-8
3-6
7-10
5-8
9-12
7-10
Discharge
Pressure
(PSIG)
220-235
190-210
280-300
250-270
Suction
Pressure
(PSIG)
120-130
120-130
125-135
125-135
Cooling - Without Desuperheater
Sub
Super
Air
Cooling
Heat
Temperature
Drop (°F-DB)
10-16
12-20
20-26
10-16
12-20
20-26
8-14
10-16
19-24
8-14
10-16
19-24
Water
Temperature
Rise (°F)
19-23
9-12
18-22
9-12
Refrigeration/Troubleshooting Guide
August, 2010
19
Roth
Section 3: Superheat/Subcooling
Figure 16: Normally-Charged System, Heating Mode
°F
90.0°F
Liquid line (heating)
psi
Load IN
GPM
To suction line bulb
°F
Liquid line (cooling)
To suction line
Superheat =
29 - 19 = 10°F
Filter Drier
TXV
For water-to-water units
substitute a second coaxial
heat exchanger for the air coil.
Air Coil
Load
Coax
°F
psi
Subcooling =
96 - 90 = 6°F
76 psi
19 °F
Suction Line (saturation)
29 °F
Suction temp
Reversing
Valve
°F
300 psi
Discharge Line (saturation)
30.0°F
Load OUT
70.0 °F
Coax
Suction
Coax
Suction
Heating
Mode
Air Coil
Return Air
Air Coil
°F
Supply Air
40.0 psi
Optional desuperheater
installed in discharge line
(always disconnect during
troubleshooting)
Source (loop) IN
Cooling
Mode
7.0
Discharge
GPM
Source
Coax
Discharge
23.5°F
36.6 psi
Source (loop) OUT
Figure 17: Under-Charged System, Heating Mode
°F
87.0°F
Liquid line (heating)
psi
Load IN
GPM
To suction line bulb
°F
Liquid line (cooling)
To suction line
Superheat =
29 - 14 = 15°F
Filter Drier
TXV
For water-to-water units
substitute a second coaxial
heat exchanger for the air coil.
Air Coil
Load
Coax
°F
psi
Subcooling =
87 - 87 = 0°F
68 psi
14°F
Suction Line (saturation)
29°F
Suction temp
Reversing
Valve
260 psi
87°F
Discharge Line (saturation)
30.0°F
Load OUT
Coax
Suction
Coax
Suction
Heating
Mode
Air Coil
Return Air
Air Coil
90.0°F
Supply Air
70.0°F
Optional desuperheater
installed in discharge line
(always disconnect during
troubleshooting)
40.0 psi
Source (loop) IN
Cooling
Mode
7.0
Discharge
GPM
Source
Coax
Discharge
26.5°F
36.6 psi
Source (loop) OUT
Roth
20
Refrigeration/Troubleshooting Guide,
August, 2010
Section 3: Superheat/Subcooling
Figure 18: Over-Charged System, Heating Mode
°F
85.0°F
Liquid line (heating)
psi
Load IN
GPM
To suction line bulb
°F
Liquid line (cooling)
To suction line
Superheat =
34 - 24 = 10°F
Filter Drier
TXV
Load
Coax
Reversing
Valve
Air Coil
For water-to-water units
substitute a second coaxial
heat exchanger for the air coil.
°F
psi
Subcooling =
101 - 85 = 16°F
85 psi
24°F
Suction Line (saturation)
34 °F
Suction temp
325 psi 101°F
Discharge Line (saturation)
30.0 °F
Load OUT
70.0°F
90.0°F
Coax
Air Coil
Coax
Suction
Air Coil
Heating
Mode
Suction
Supply Air
Return Air
40.0 psi
Optional desuperheater
installed in discharge line
(always disconnect during
troubleshooting)
Source (loop) IN
Cooling
Mode
Source
Coax
GPM
Discharge
Discharge
26.5°F
36.6 psi
Source (loop) OUT
Figure 19: Water-to-Air Refrigerant Circuit with Desuperheater
°F
psi
°F
Liquid line (heating)
Load IN
GPM
To suction line bulb
°F
Liquid line (cooling)
To suction line
Filter Drier
TXV
For water-to-water units
substitute a second coaxial
heat exchanger for the air coil.
Air Coil
Load
Coax
°F
psi
psi
°F
Suction Line (saturation)
°F
Suction temp
Reversing
Valve
psi
°F
Discharge Line (saturation)
°F
Load OUT
°F
Supply Air
psi
Coax
Source (loop) IN
Suction
Air Coil
Coax
Suction
Heating
Mode
Air Coil
°F
Return Air
Cooling
Mode
GPM
Source
Coax
Desuperheater
Discharge
Discharge
°F
psi
Source (loop) OUT
Refrigeration/Troubleshooting Guide
August, 2010
21
Roth
Section 4: Desuperheater Operation
The desuperheater option includes a waterto-refrigerant coaxial heat exchanger
installed between the compressor
discharge line and reversing valve,
which is connected to the condenser
(air coil in heating, coax in cooling) as
shown in figure 19. Unlike the source
coax in all Roth geothermal heat pumps,
the desuperheater coax is a doublewall, vented water-to-refrigeration heat
exchanger. Figure 20 illustrates a cut-away
of the desuperheater coax.
The operation of the desuperheater
takes advantage of the superheat at
the discharge line. For example, in figure
16, the discharge pressure is 300 psi. The
saturation temperature at 300 psi is 96°F.
The discharge line at these conditions
would typically be around 160°F. Therefore,
the superheat (actual temperature
– saturation temperature) is 64°F. As
domestic hot water flows through the
desuperheater heat exchanger, some of
the superheat at the discharge line is used
to heat domestic water, which lowers the
superheat at the discharge line, thus the
term desuperheater.
In heating, the desuperheater takes some
of the heat that would have been used
to heat the space via the condenser (air
coil), and uses it to make domestic hot
water. Even though the desuperheater
is “robbing” some of the heat from the
space, it is a very small amount, and the
system is heating water at a very high
C.O.P. (3.0 to 4.0, depending upon loop
temperature), compared to an electric
water heater at a C.O.P. of 1.0.
Some geothermal heat pumps turn off the
desuperheater pump when back up heat
is energized. However, studies show that on
an annual basis, the system is more energy
efficient when the desuperheater is utilized
any time the compressor is running. When
the hot water tank is already heated, a
thermal switch turns off the desuperheater
pump. The pump may also be turned off if
the compressor discharge line is too cool.
Figure 20: Desuperheater coax cut-away
Steel Outer Wall
Rifled Copper Tube
Water flow rate through the desuperheater
coax must be very low to avoid turning
the desuperheater into a condensor, and
“robbing” too much heat from the main
condenser. Typically, about 0.4 GPM per
ton is used for desuperheater flow rate. The
desuperheater pump operates anytime the
compressor is operating (unless the one of
the temperature limits is open).
Smooth Wall
Inner Tube
Refrigerant
Air Gap
Water
In cooling, the desuperheater takes some
of the heat that would have been rejected
to the ground loop via the condenser
(coax), and uses it to make domestic
hot water. Therefore, the desuperheater
produces nearly free hot water (other
than the fractional horsepower circulating
pump) in the cooling mode.
Roth
22
Refrigeration/Troubleshooting Guide,
August, 2010
Troubleshooting Form
Please make copies of this form.
Customer/Job Name:____________________________________________ Date:________________________________
Model #:__________________________________________ Serial #:____________________________________________
Antifreeze Type:____________________________________
Diagram: Water-to-Air and Water-to-Water Units
°F
psi
°F
Liquid line (heating)
Load IN
GPM
°F
Liquid line (cooling)
To suction line bulb
To suction line
Note: DO NOT connect
refrigerant gauges
until Heat of Extraction
or Rejection has been
checked.
Filter Drier
TXV
For water-to-water units
substitute a second coaxial
heat exchanger for the air coil.
Air Coil
Load
Coax
°F
psi
psi
°F
Suction Line (saturation)
°F
Suction temp
Reversing
Valve
psi
°F
Discharge Line (saturation)
°F
Load OUT
Coax
Suction
Coax
Suction
Air Coil
Heating
Mode
Air Coil
°F
Supply Air
°F
Return Air
Optional desuperheater
installed in discharge line
(always disconnect during
troubleshooting)
psi
Source (loop) IN
Cooling
Mode
GPM
Discharge
Source
Coax
Discharge
Note: Disconnect desuperheater before proceeding
°F
psi
Source (loop) OUT
HE or HR = GPM x TD x Fluid Factor
(Use 500 for water; 485 for antifreeze)
SH = Suction Temp. - Suction Sat.
SC = Disch. Sat. - Liq. Line Temp.
Refrigeration/Troubleshooting Guide
August, 2010
23
Roth
P.O. Box 245
Syracuse, NY 13211
888-266-7684 US
800-969-7684 CAN
866-462-2914 FAX
www.roth-america.com
info@roth-usa.com
**
*
* AHRI certification is shown as the Roth brand under the Enertech Manufacturing certification reference number
**Roth Industries geothermal heat pumps are shown as a multiple listing of Enertech Manufacturing’s ETL certification
*** Roth geothermal heat pumps are listed as a brand under Enertech Manufacturing’s Energy Star ratings
***