Marley Electric Basin Heater
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User Manual 92-1322C
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/ Receiving and Inspection /
The heater package is shipped directly from the vendor.
1. Check all parts for any damage in transit. The carrier is responsible
for the condition of the heater package upon arrival. If damage is appar-
ent, note the freight bill accordingly. This will support your claim with the
freight carrier.
2. Check the nameplate on the enclosure and verify that the heaters and
the control panel are rated for the correct voltage.
3. Check the watt rating on each element and verify the sum of all elements
is equal to the KW rating as ordered.
4. The control panel is nameplated for the maximum amperage that the
panel can safely control and may be equal to or greater than the actual
amperagerequiredforyourheaterpackage.SeeInstallationInstructions
on page 5 to calculate amperage required.
3
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/ Introduction /
The purpose of a basin heater is to prevent water freezing in the cooling
tower basin during periods of shutdown or standby operation. The heater
system is sized according to tower model and location to give maximum
protection against water freezing in the cold water basin. This heating
system is not intended to protect the tower fill and other components
from icing. Refer to Marley Technical Bulletin # H-002 "Operating Cooling
Towers in Freezing Weather." Contact your Marley Sales Representative
for a copy of this publication.
The Marley basin heater system is manufactured by INDEECO, a leader
in immersion heating equipment. The system is referred to as a "heater
package"andconsistsofimmersionheaters,acontrolpanelandcombina-
tion temperature / liquid level sensor with a 12'-0" cable length. The basic
control panel contains a contactor(s) of sufficient capacity for the heater
elements selected. In addition the panel contains a transformer to reduce
line voltage to 24VAC for panel control power, and a solid state relay card
to detect low temperature and low water conditions. The panel enclosure
is rated NEMA 4X (liquid tight, noncorrosive) and the sensor cable is UL
outdoor rated. The sensor probe is stainless steel with 1⁄2" NPT threads
and a PVC bulkhead fitting for installation in the cold water basin.
The panel may control more than one heating element, up to its nameplate
KW rating for the voltage and phase stated. In addition to the components
of the basic panel described above, available options are fusing, circuit
breakers or disconnect switches. The circuit diagram located on the inside
of the panel cover will indicate the panel configuration.
The following defined terms are used throughout this manual to bring at-
tention to the presence of hazards of various risk levels, or to important
information concerning the life of the product.
Indicates presence of a hazard which can cause severe personal
injury, death or substantial property damage if ignored.
Warning
Caution
Indicatespresenceofahazardwhichwillorcancausepersonalinjury
or property damage if ignored.
Indicatesspecialinstructionsoninstallation,operationormaintenance
which are important but not related to personal injury hazards.
Note
4
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/ Installation /
For detailed information concerning installation, refer to the heater
installation drawing provided with the cooling tower.
Note
Heater Element
Install the heater element(s) in the depressed area of the cold water basin
near the outlet. Provide clearance of 7⁄8" or more above the floor.
A single centrally located heater can protect up to 300 square feet of basin
surface area from ice damage. To protect larger surface areas, position
several heaters so they protect equal areas. For multicell towers, no more
than two cells may be protected by a single heater package. For three or
more cells additional heater packages are necessary.
The heater should never operate out of the water. It would become
extremely hot (1500°F) and destroy the heater element and/or ig-
nite nearby combustible materials. As a precaution and to prevent
fires when the clearance between any part of a heater element and
combustible materials is less than 10", install a sheet metal shield
to reflect and dissipate the heat. The shield must not contact the
heater element and should extend beyond the heater element in all
directions as shown in Table 1.
Caution
Heater Clearance inches
1
2
9
4
7
6
4
8
2
10
0
Table 1
Shield Extension inches
10
Heater Supports
Install metal supports for the heater element where necessary to keep
the unsupported length under 30". The number of supports required is
as shown in Table 2.
Heater Kilowatts
1 - 9
12-18
1
Table 2
Number of Supports
None
5
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/ Installation /
Control Panel
The control panel is suitable for outdoor mounting, and may be mounted
on the tower, but not inside the tower. Wire the heaters to the panel. Wire
the panel to the branch circuit supplying power to the heater.
The field supplied branch circuit disconnect switch and the branch circuit
protective device (fusing or circuit breaker) shall be sized in accordance
with the NEC/CEC rules for actual load. The total heater load can be
calculated as shown below.
If the heater control panel is furnished with an optional disconnect, in-
stallation of the panel in relationship to the heater element shall be in
accordance with the NEC/CEC rules.
The main incoming conduit hub and the main power termination points are
sized for total nameplate KW and voltage. The actual load for a particular
installationmaybeless.Eithercomputetheactualloadontheheatercontrol
panel to determine the sum total KW of all the heaters connected to it or
use the nameplate rating to determine the wire size required. To calculate
amp draw for a particular installation use the following formulas:
KW x 1000
= Amperage for Single Phase Applications
Voltage
or
KW x 1000
= Amperage for Three Phase Applications
1.7312 x Voltage
Should water be drained, either intentionally or accidentally, from
the basin, the basin heater MUST be checked manually to insure the
power source to the heating element is OFF. Although equipped with
a low liquid level sensor probe, contaminants on or around the probe
may cause false readings allowing the element to remain energized
under low or no water conditions. Do not re-energize the unit until
the sensor probe is fully submerged in water.
Caution
IF THE UNIT IS ENERGIZED WHILE THE SENSOR PROBE IS NOT
FULLY SUBMERGED IN WATER, COMBUSTION/FIRE MAY RESULT,
WHICHCOULDDAMAGEORDESTROYTHETOWERANDMAYCAUSE
DAMAGE TO PERSONS OR PROPERTY NEARBY.
6
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/ Installation /
Temperature / Water Level Sensor Assembly
This basin heater package is equipped with a combination tempera-
ture/liquid level sensor and may have a thermal cutoff switch. Both
are safety devices that must not be altered or changed in any man-
ner. Disabling either safety feature may result in combustion and/
or fire, which could cause damage or destroy the tower and may
cause damage to persons or property nearby. Failure of one or both
safety devices requires that the control panel be de-energize and
tag circuit out for maintenance. Do not re-energize the unit until all
safetydevicesarefullyoperationalinaccordancewithmanufacturer's
specifications.
Warning
The sensor assembly is factory installed to the control panel. Do not at-
tempt to lengthen or shorten the cord. Sensor assemblies with various
lengths up to 99'-0" are available and may be specified at the time of
purchase for additional cost.
Install the sensor probe in the cold water basin at least 1" above the high-
est point of the heater element and at least 6" away from the heater. The
probe should be installed in the coldest part of the basin for maximum
protection. It should extend into the open basin a minimum of 4". A1⁄2" NPT
PVC bulkhead fitting is provided on the sensor for mounting through the
basin wall. Provide an 15⁄8" clearance hole through the basin wall. Remove
the nut from the bulkhead fitting and insert the sensor probe through the
hole. Hand tighten the mounting nut onto the fitting, holding the bulkhead
fitting to avoid twisting the cord. Lightly tighten the nut.
7
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/ Operation /
Operating Instructions
To operate the heater system, visually check that the water level is above
the sensor probe before energizing the power supply. The temperature
controlispresetat45°F. Thesystemwillnotenergizeunlessthewaterlevel
is above the sensor probe and the temperature of the water is below the
45° set point. The solid state relay card located in the control panel has
a green and a red LED—see Figure 1. In a "ready" condition, with water
level above the sensor probe and temperature above 45°F both these
LEDs will be off. If the red LED is illuminated this indicates a low water
condition and the heaters will not operate. If the green LED is illuminated
the heater elements are on.
SOLID STATE RELAY CARD
Figure 1
Table 3
RED
PROBE
BLK
RED
BLK
COM
NC NO
SHIELD
BASIN
LED INDICATORS
Red
OFF
ON
Green
OFF
OFF
ON
Ready, No Demand
Low Water Level
Heater On
OFF
Should water be drained, either intentionally or accidentally, from
the basin, the basin heater MUST be checked manually to insure the
power source to the heating element is OFF. Although equipped with
a low liquid level sensor probe, contaminants on or around the probe
may cause false readings allowing the element to remain energized
under low or no water conditions. Do not re-energize the unit until
the sensor probe is fully submerged in water.
Caution
IF THE UNIT IS ENERGIZED WHILE THE SENSOR PROBE IS NOT
FULLY SUBMERGED IN WATER, COMBUSTION/FIRE MAY RESULT,
WHICHCOULDDAMAGEORDESTROYTHETOWERANDMAYCAUSE
DAMAGE TO PERSONS OR PROPERTY NEARBY.
8
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/ Operation /
Testing above Freezing Temperatures
Under normal operating conditions the heaters will be turned on at a
water temperature between 40° and 45°F, and turned off when the water
temperature exceeds 45°F. For testing the system at temperatures above
45°F there are two methods as follows:
Method A
1. Disconnect power to the control panel using standard lockout proce-
dure for safety.
2. Remove the panel cover
3. Remove the sensor wires connected to terminals T1 and T2 on the
relay circuit board.
SOLID STATE RELAY CARD
Figure 2
RED
PROBE
BLK
RED
BLK
COM
NC NO
SHIELD
RESISTOR
BASIN
4. Connect a 1.5K ohm resistor (included in panel) across T1 and T2
terminals—see Figure 2.
5. Replace panel cover and verify probe is submerged in tower basin
water.
6. With panel cover in place turn on power supply to the system. An au-
dible CLICK should be heard as the contactor engages. If this does not
happen, refer to the Troubleshooting section of this manual.
7. If the system tests OK turn off power, remove the panel cover and re-
move the resistor. Replace sensor wires T1 and T2 and replace the cover.
Turn system on.
➠
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/ Operation /
Method B
1. Disconnect power to the heater control panel using standard lockout
procedures for safety.
2. Drain basin until the water level is below the probe allowing removal of
the probe. Make sure water still covers the heater elements.
3. Place the probe in a container of ice water making sure both metal parts
of the probe are submerged but not the cord.
4. Energize the heater control panel. Allow 5 min. for the probe tempera-
ture to stabilize.
5. An audible CLICK should be heard as the heater contactor engages. If
this does not happen, refer to the Troubleshooting section.
10
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/ Operation /
Deicing
If the temperature/water level sensor assembly becomes encased in ice
the heaters will not operate. Ice provides inadequate conductivity for the
sensor probe to detect operational water level. To operate heaters in this
situation and melt the ice follow these procedures.
1. Disconnect power to the control panel using standard lockout proce-
dures for safety.
2. Remove the panel cover.
3. Install a jumper wire between relay terminals G1 and G2—see
Figure 3.
JUMPER
SOLID STATE RELAY CARD
RED
Figure 3
PROBE
BLK
RED
BLK
COM
NC NO
SHIELD
BASIN
4. Replace panel cover.
5. Energize the system and listen for contactor closing.
6. Operate the system until ice is melted around the sensor probe.
7. After ice is melted, de-energize the system, remove the jumper, check
all connections and place the system back in operation.
Do not leave the heating system unattended during this procedure.
There is no low water protection with this jumper in place.
Caution
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/ Troubleshooting /
Please refer to the Caution statement on Page 6 and the Warning
statement on Page 7 of this manual before performing the following
Troubleshooting procedures.
Caution
If the system fails to operate, check the following:
1. Check water temperature. Systems will turn on between 40° and 45°F
and turn off above 45°F.
2. Check water level. Water must completely cover the sensor probe.
3. Make sure the sensor is not encased in ice. See Deicing procedure.
The following checks should be made by a qualified electrician.
Caution
4. Remove panel cover and check incoming electrical power for proper
voltage. Make sure all phases are present. Correct as required.
5. If water level is adequate, temperature is 40°F or lower and power is
present, observetheLEDsontherelaycircuitboard. TheredLEDindicates
low water level or ice around the probe and the green LED indicates the
heaters are energized.
A. If the red LED is on and the sensor probe is submerged in water—no
ice—this indicates the sensor probe is defective. Confirm by discon-
necting power and placing a jumper across terminals G1 and G2—see
Figure 3. Reconnect power. If the red LED is now off and the green
LED is on, the system is now operating. Replace sensor probe.
B. If the green LED is on and the heaters are not operating, the problem
is either the contactor, the relay circuit board or the heater elements.
To determine which, observe the panel while power is disconnected
and reconnected.
1. If the contactor operates with an audible CLICK and no heat results
the heater element is defective. Check voltage at the heater side of
the contactor to confirm voltage is present. Check each line with a
clamp-on amp meter. If voltage is present and no current is flowing,
this indicates the element is defective and must be replaced. As an ad-
ditionalcheck,disconnect power,removewiresfromthecontactorand
check the element with an ohm meter for measurable resistance.
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/ Troubleshooting /
2. If the contactor does not operate, check voltage across terminal N
on the circuit board and NO on the relay mounted on the circuit board
—21-29 volt required. If voltage is present across the coil—N to NO—
the contactor coil is defective and the contactor must be replaced. If
voltage is not present, the circuit board relay is defective and the circuit
board must be replaced.
C. If the green LED is off and the red LED is also off the problem is either
the circuit board, the sensor probe, or the transformer. To determine
which check as follows:
1. Disconnect power and remove wires T1 and T2 from the circuit
board. Replace with the 1.5K ohm resistor provided. See Figure 2.
If the system now works, the sensor probe is defective and must be
replaced. If the system does not work, go to step 2.
2. Reconnect power and take a voltage reading across N and 24/240
on the circuit board—21-29 volts required. If proper voltage is not
present the transformer is defective and must be replaced. If proper
voltage is present go to step 3.
3. Take a voltage reading across N and NO—21-29 volts required. If
proper voltage is not present, replace circuit board.
6. The sensor assembly can be checked for accuracy in the following
manner.
Remove wires T1 and T2 from the circuit board and measure ohm
readings across these wires. Measure the water temperature that the
probe is being exposed to. Compare with the following values.
Temp °F
0
ohms
4273
3126
2312
1633
1305
1138
765
Table 4
10
20
32
40
45
60
75
525
85
412
13
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/ Parts List /
1
2
24
240 120
N
CT
3
4
RED
GREEN
SH T1 T2 G1 G2
5
Replacement Parts
1
Transformer 120V/24V.............................................. B52465D
Transformer 208V/24V.............................................. A79270D
Transformer 240V/24V.............................................. B91566D
Transformer 480V/24V.............................................. B09608D
Transformer 600V/24V.............................................. B62553D
Contactor 50 amp, 600V, 24 volt coil........................ C32328D
Solid State Relay Card.............................................. A79269D
Sensor Probe with 12' cord...................................... A81137D
Sensor Probe with 22' cord...................................... B07688D
–contact Marley for other cord lengths
2
3
4
5
Heater Element—contact Marley for specific heater elements
Call your Marley Sales Representative for replacement parts. For the location
of your Marley Sales Representative call 913·664·7400 or check the web at
spxcooling.com.
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7401 WEST 129 STREET OVERLAND PARK, KANSAS 66213 UNITED STATES 913 664 7400 [email protected] spxcooling.com
In the interest of technological progress, all products are subject to design and/or material change without notice.
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©2008 SPX Cooling Technologies, Inc. Printed in USA
Manual 92-1322C
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