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5-Year Limited Solar Warranty
This Five Year Limited Warranty statement is only applicable to Solar controls and accessories
sold and installed within the USA and Canada* and supersedes any warranty statements dated
prior to November 1, 2010.
Hayward warrants its Hayward solar products to be free from defects in material or workmanship,
under normal use and service for 5 years from date of manufacture, providing it is installed
according to the installation instructions and specifications. The datecode stamped on the
outside of the product and also coded on the printed circuit board will be the sole determination
of manufacturing date.
To obtain warranty service or repair, please contact the place of purchase or the nearest Hayward
authorized warranty service center. For more information, please contact the Hayward
Technical Service Support Center or visit us on the web at www.haywardnet.com. Hayward will
not assume any of the cost incurred in removal or reinstallation of the product. One year outside
the USA and Canada.
The express warranty above constitutes the entire warranty of Hayward Pool Products with
respect to its solar products and IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED
OR IMPLIED, INCLUDING A WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE.
IN NO EVENT SHALL HAYWARD BE RESPONSIBLE OR ANY CONSEQUENTIAL OR
INCIDENTAL DAMAGES OF ANY NATURE WHATSOEVER.
No wholesaler, agent, dealer, contractor, or other person is authorized to give any warranty on
behalf of Hayward. This warranty is void if the product has been altered in any way after leaving
the factory.
Charges
Years 1-3: no charge
Years 4-5 60% of current list price plus $5.00 shipping and handling
Aqua Solar
GL-235
Electronic Solar Control
Unless a copy of the original purchase invoice is enclosed, the manufacturing datecode on the
product will be used to determine the repair charges. Hayward reserves the right to charge a
nominal fee to cover inspection, test, and return freight for all controls where no faults or
problems are detected. All charges will be COD (COD charge will be included) unless you
already have an open account in good standing with Hayward. If the product returned can not
be repaired, Hayward will offer and equivalent credit towards the purchase of any new
Hayward product. Products that exhibit evidence of abuse, misuse, field damage (water/fire
damage, line voltage applied to low voltage terminals, missing parts, etc.) or installed for
more than the warranty period are not eligible for warranty repair replacement.
620 Division St.
Elizabeth, NJ 07207
Copyright © 2010 Hayward Inc.
092007G RevH
Operation and Installation
Manual
GL-235
www.haywardnet.com
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Description
40
26,100 3.61809,29
2.41
120
3
1.37160
1,688
0.72
The GL-235 is a differential temperature control for solar heating of pools, spas, and hot
tubs. It provides differential temperature control with an adjustable, calibrated water
temperature high limit. Automatic nocturnal cooling (for pools that overheat in hot
climates) and recirculate freeze protection functions can be enabled/disabled via
internal jumpers.
Input power can be either 115 or 240 VAC. The output controls a 24VAC automatic valve
actuator. For older systems with 12VAC valves, an internal jumper can be moved to
select 12VAC output operation. The GL-235 also has a high voltage output for
controlling a filter pump or booster pump.
Specifications
Power: 105-130VAC, .5A 50/60Hz.
or
195-250VAC, .3A 50/60Hz
Output: Selectable low voltage
24VAC, 20VA, .85A
or
12VAC, 20VA, 1.7A
SPST-NO isolated contact
115VAC 1HP
240VAC 2HP
Sensors: 2 required (thermistor,
10Kohm @ 25C/77ºF).
Differential: on at 4ºF, off at 1.5ºF
Desired
Pool
Temp.: 70-104ºF calibrated scale
or Solar Off, 75 (24ºC) 104ºF (40ºC) on some
models
Recirculate
freeze: On at <40ºF (4.5ºC), off at
> 42ºF (5.5ºC),
Enabled via jumper
Nocturnal
cooling: On when collector 8ºF
less than pool and pool
hotter than limit, off when
collector 3ºF less than
pool or pool cooler than
high limit. Enabled via
jumper
Installation
Mounting
The GL-235 is designed for outdoor use. Mount the box vertically with the knockouts
facing downward. For safety, the GL-235 must be a minimum of 5 feet (horizontally) from
the pool or spa.
Power input
Turn off power at circuit breaker before wiring. Remove the internal panel to expose
the wiring connections. Either 115VAC or 240VAC can be used. Refer to the input wiring
diagram (Figure 1) on next page. WARNING: Applying 240VAC to the 120VAC input
terminals will cause permanent damage to the control.
Grounding
Refer to NEC and local codes for specific grounding requirements. In general, a separate
ground conductor must be run to the ground terminal on the pool service panel.
Low Voltage (LV) output: Solar Valve
The GL-235 controls a single valve. In most applications this is the solar valve, which
diverts water through the collector panels or through the normal pool loop depending
on conditions.
With the sensor disconnected from the unit, measure the resistance of the sensor using
an ohmmeter. At room temperature (25ºC/77ºF) the sensor should measure approximately 10K ohms (10,000 ohms ± 1%). For other resistance measurements at different
temperatures, consult the table at back of manual. If the sensor is not returning the
correct value, it is defective and will need to be replaced. If the sensor is returning
approximately the correct value, reconnect it to the terminals marked “SOLAR SENSOR”. If the “CHECK SENSOR” indicator remains on, the unit is defective and needs
to be replaced.
If FREEZE PROTECTION is enabled:
When a sensor is disconnected from the unit and freeze protection has been enabled,
the GL-235 will recognize this as a freeze condition and activate freeze protection.
Temperature/Resistance/Voltage
All Hayward controls use 10K thermistor sensors. When disconnected from the control
the sensor will read 10K ohms at 25ºC/77ºF. Refer to the chart below for the resistance
at other temperatures. For a given temperature, the resistance reading should be
accurate to ±1%. For a given resistance reading, the temperature reading should be
accurate to ±0.5ºF. Voltage measurements should be accurate to ± 2%. Ohm
measurements made with sensor disconnected from unit. Voltage measurements made
with sensor connected to unit and power applied. Sensor voltages are DC volts.
°F Ohm sVolts °F OhmsVolts °F OhmsVolts °F OhmsVolts
1 82,719 4.46 41 25,391 3.59 81 9,076 2.38 121 3,679 1.34
2 80,142 4.45 42 24,704 3.56 82 8,861 2.35 122 3,602 1.32
3 77,656 4.43 43 24,037 3.53 83 8,651 2.32 123 3,527 1.30
4 75,255 4.41 44 23,391 3.50 84 8,447 2.29 124 3,454 1.28
5 72,937 4.40 45 22,764 3.47 85 8,249 2.26 125 3,382 1.26
6 70,698 4.38 46 22,156 3.45 86 8,056 2.23 126 3,312 1.24
7 68,535 4.36 47 21,566 3.42 87 7,867 2.20 127 3,244 1.22
8 66,447 4.35 48 20,993 3.39 88 7,684 2.17 128 3,177 1.21
9 64,428 4.33 49 20,438 3.36 89 7,506 2.14 129 3,112 1.19
10 62,479 4.31 50 19,900 3.33 90 7,333 2.12 130 3,049 1.17
11 60,595 4.29 51 19,377 3.30 91 7,164 2.09 131 2,987 1.15
12 58,774 4.27 52 18,870 3.27 92 6,999 2.06 132 2,926 1.13
13 57,014 4.25 53 18,377 3.24 93 6,839 2.03 133 2,867 1.11
14 55,313 4.23 54 17,899 3.21 94 6,683 2.00 134 2,809 1.10
15 53,669 4.21 55 17,435 3.18 95 6,530 1.98 135 2,752 1.08
16 52,078 4.19 56 16,985 3.15 96 6,382 1.95 136 2,697 1.06
17 50,541 4.17 57 16,548 3.12 97 6,238 1.92 137 2,643 1.05
18 49,054 4.15 58 16,123 3.09 98 6,097 1.89 138 2,591 1.03
19 47,616 4.13 59 15,711 3.06 99 5,960 1.87 139 2,539 1.01
20 46,225 4.11 60 15,310 3.02 100 5,827 1.84 140 2,489 1.00
21 44,879 4.09 61 14,921 2.99 101 5,697 1.81 141 2,440 0.98
22 43,577 4.07 62 14,543 2.96 102 5,570 1.79 142 2,392 0.97
23 42,318 4.04 63 14,176 2.93 103 5,446 1.76 143 2,345 0.95
24 41,099 4.02 64 13,820 2.90 104 5,326 1.74 144 2,299 0.93
25 39,919 4.00 65 13,473 2.87 105 5,208 1.71 145 2,254 0.92
26 38,777 3.97 66 13,136 2.84 106 5,094 1.69 146 2,210 0.90
27 37,671 3.95 67 12,809 2.81 107 4,982 1.66 147 2,167 0.89
28 36,601 3.93 68 12,491 2.78 108 4,873 1.64 148 2,125 0.88
29 35,565 3.90 69 12,182 2.75 109 4,767 1.61 149 2,084 0.86
30 34,561 3.88 70 11,882 2.72 110 4,664 1.59 150 2,044 0.85
31 33,590 3.85 71 11,589 2.68 111 4,563 1.57 151 2,005 0.84
32 32,648 3.83 72 11,305 2.65 112 4,464 1.54 152 1,966 0.82
33 31,737 3.80 73 11,029 2.62 113 4,368 1.52 153 1,929 0.81
34 30,853 3.78 74 10,761 2.59 114 4,274 1.50 154 1,892 0.80
35 29,998 3.75 75 10,500 2.56 115 4,183 1.47 155 1,856 0.78
36 29,169 3.72 76 10,246 2.53 116 4,094 1.45 156 1,821 0.77
37 28,365 3.70 77 9,999 2.50 117 4,007 1.43 157 1,787 0. 76
38 27,587 3.67 78 9,758 2.47 118 3,922 1.41 158 1,753 0. 75
39 26,832 3.64 79 9,525 2.44 119 3,839 1.39 159 1,720 0. 73
7
,758
All controls are shipped with the output voltage set to the industry standard 24VAC.
To use the GL-235 with older 12VAC valves, move jumper J4, located on the right side
of the circuit board.
2 11
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Troubleshooting
g
No Power Indicator
•
Check main power circuit breakers.
•
Check fuse
Fuse Replacement
The GL-235 is protected by a fuse located on the left side of the main circuit board.
Replace the fuse with a 2A, type ATO-2 fuse, readily available in most automotive or
electronics stores.
If “Heating” is always on
Disable recirculate freeze protection if enabled. Check that the switch is in the “AUTO”
position. Next verify that the control circuitry is operating properly by disconnecting
the solar sensor from the terminal block. The “Heating” LED should go off and the
“CHECK SENSOR” LED should begin to blink. If “Heating” remains on, there is an
internal circuit failure and the GL-235 will have to be returned for repair.
If “Heating” never comes on
Verify that the switch is in the “AUTO” position, the desired pool temperature dial is
set higher (hotter) that the actual pool temperature, and the solar sensor is warmer than
the pool water. Also check that the switch on the valve actuator is NOT in the "OFF"
position. Disconnect the pool sensor from the terminal block and verify that the
“CHECK SENSOR” LED turns on. If the “CHECK SENSOR” LED does not turn on, there
is an internal failure and the GL-235 will have to be returned for repair. Reconnect the
pool sensor and verify that the “Check Sensor” LED turns off. Next, disconnect the
“solar” sensor from the terminal block and verify that the “CHECK SENSOR” LED
begins to blink. If the “CHECK SENSOR” LED does not begin to blink, there is an internal
failure and the GL-235 will have to be returned for repair.
“CHECK SENSOR” indicator on
If the “CHECK SENSOR indicator is on and NOT blinking, there may be a possible open
circuit or short circuit with the pool sensor. Using a voltmeter, measure the DC voltage
across the terminals of the pool sensor as indicated in figure 5. If the voltage is close
to zero volts, the sensor has a short to ground. Remove the sensor from the terminal
block and measure the voltage across the pool terminals again. If the voltage is still close
to zero volts, there is an internal short and the unit must be returned for repair. If the
voltage is close to five volts, the pool sensor itself may be at fault.
With the sensor disconnected from the unit, measure the resistance of the sensor using
an ohmmeter. At room temperature (25ºC/77ºF) the sensor should measure approximately 10K ohms (10,000 ohms ± 1%). For other resistance measurements at different
temperatures, consult the table at back of manual. If the sensor is not returning the
correct value, it is defective and will need to be replaced. If the sensor is returning
approximately the correct value, reconnect it to the terminals marked “POOL SENSOR”.
If the “CHECK SENSOR” indicator remains on, the unit is defective and needs to be
replaced.
The GL-235 provides two different types of connections to the pool/spa actuators. For
older actuators with no wire end connector, a 3 position terminal block is used. Connect
the wires to the proper terminal block according to the color code shown in Figure 4.
If the valve operates opposite to the way it is supposed to, reverse the red and white
wires. Be careful not to short the valve output wiring. The GL-235 is fused and shorting
the output will require replacing the fuse.
For newer Hayward, Compool and Jandy actuators (with wire end connectors), two 3pin connectors are supplied. Plug the actuator into one of the two 3 pin connectors
as shown in figures 2 or 3. If the valve operates opposite to the way it is supposed to,
disconnect and plug into the other connector.
High Voltage (HV) output: Booster Pump
The GL-235 can control a high voltage booster pump in addition to the normal low
voltage solar valve. Note the high voltage relay contacts are isolated so that the booster
pump can be run on a separate circuit, as required by many local codes. The GL-235
turns on, the valve output will operate first, and then the HV relay will operate 30 seconds
later.
High Voltage (HV) output: Timeclock Override
The GL-235 can also be used to override the filter pump timer. This is very important
if recirculate freeze protection or nocturnal cooling functions are being used. Also, this
function can be used on systems where the system should operate whenever solar heat
is available, regardless of the timer settings. The HV relay will operate approximately
30 seconds after the LV relay.
Sensor Mounting and Wiring
Most installations use a PC sensor to measure the pool temperature and another PC
sensor to measure the solar temperature. Alternatively, an SC-¼ sensor can be screwed
into the pump strainer basket to measure the pool temperature.
Pool Sensor: Drill a 3/8” (or 5/16”) hole in the PVC pipe. Remove burrs around the hole.
Check that the O-ring is seated on the PC sensor and then insert sensor into pipe.
Tighten hose clamp over the sensor to make a seal—DO NOT OVERTIGHTEN.
Solar Sensor: Use a screw or silicon adhesive to attach the sensor near the solar
collector array. The sensor does not have to be attached to the collectors. It is only
important that the sensor be exposed to the same sunlight as the collectors. Additionally, the underside of the sensing element may be covered with silicon to minimize wind
cooling.
Other 10K ohm Hayward sensors may be substituted. Wire should be twisted pair
20AWG. Sensor wiring run outdoors must be rated for outdoor use and ensure that
the wire connections are protected from the weather. Do NOT run sensor wires in the
same conduit or multiconductor cable as the valve actuator wires or any 120/240V
circuit. For long runs or runs near other electrical wiring use shielded cable (Belden
8428 for outdoor use). Ground the shields to the GL-35/LV ground screw.
“CHECK SENSOR” indicator blinking
If the “CHECK SENSOR indicator is blinking, there may be a possible open circuit or
short circuit with the solar sensor. Using a voltmeter, measure the voltage across the
terminals of the solar sensor. If the voltage is close to zero volts, the sensor has a short
to ground. Remove the sensor from the terminal block and measure the voltage across
the solar terminals again. If the voltage is still close to zero volts, there is an internal
short and the unit must be returned for repair. If the voltage is close to five volts, the
solar sensor itself may be at fault.
EARTH
GROUND
240 VAC
input power
high
voltage
output
{
Figure 1
310
EARTH
GROUND
115 VAC
input power
high
volta
output
{
e
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Freeze Protection
If you are relying on the collectors naturally draining to provide freeze protection, it is
very important that you use a
diverter of a positive seal valve to allow the collectors to drain. Alternatively, the GL235 control can provide recirculate freeze protection. If enabled, when the GL-235
senses a freeze condition at the collector sensor, it will allow circulation of relatively
warm water from the pool to the collector panels.
The GL-235 will allow recirculation when the collector temperature falls below 40ºF and
will stop circulation when the collector temperature rises above 42ºF. While this type
of freeze protection has proven to be adequate in relatively mild climates, it is extremely
important that the sensors be properly placed and that the homeowner realize that the
system is unprotected in the event of a power failure. Recirculate freeze protection is
NOT recommended in climates where freezing temperatures are common or last for
extended periods.
Hayward strongly recommends the use of GC-3 freeze snap switches if freeze protection
is being utilized. Snap switches should be wired in series with the collector sensor.
Placement of the snap switches at the coldest point of the collector array and exposed
plumbing will help assure that freeze protection starts early enough to protect the
system.
The GL-235 is shipped from the factory with recirculate freeze protection disabled (the
jumper is present but installed on one pin only). To activate recirculate freeze
protection, install the jumper across both pins marked “RECIRC”, located near the top
right of the main circuit board.
If recirculate freeze protection is to be used on a GL-235, either:
• The filter pump must be set for continuous operation
or
• The GL235 High Voltage Output must be wired for Timer Override function.
non-positive seal valve or drill a hole (1/8"--1/4") in the
Nocturnal Cooling
The GL-235 has nocturnal cooling logic, which can be enabled/disabled via a jumper
on the main circuit board. During nighttime hours, when enabled, the GL-235 will
circulate relatively warmer water from the pool to the collector panels, thus cooling the
pool over time. The GL-235 will circulate water when the collector temperature AND
the pool temperature is hotter than the high limit setting. Circulation will stop when the
collector temperature is 3ºF less than the pool temperature OR the pool temperature is
cooler than the high limit setting. The GL-235 is shipped from the factory with nocturnal
cooling disabled (the jumper is present but installed on one pin only). To activate
nocturnal cooling, install the jumper provided onto the two pins marked “COOLING”
located near the top right of the main circuit board.
If nocturnal cooling is to be used, either:
• The filter pump must be set for continuous operation
or
• The GL235 High Voltage Output must be wired for Timer Override function.
4
(Use the same method to measure the Solar Sensor)
Measuring Voltage of Pool Sensor
Figure 5
9
Page 5
Operation
For normal operation place the switch in the “AUTO” position and adjust the desired
pool/spa temperature setting. The “Power” LED indicator should always be on. (NOTE:
During initial power up, the “POWER indicator will blink for approximately 10 seconds
while it stabilizes temperature readings). The “Heating” LED indicator will show when
the system is collecting solar heat. If the nocturnal cooling function is enabled inside
the GL-235, the “Cooling” LED indicator will show when the system is dissipating
excess heat.
In the “AUTO” position, the GL-235 will heat the pool or spa (rotate valve to solar loop)
when the collector (solar) sensor temperature is higher than the pool/spa sensor
temperature by 4ºF or more AND the pool/spa temperature is less than the "Desired
Temperature" setting. The GL-235 will stop heating (return valve to pool loop) when
the two sensor temperatures get to within 1.5ºF OR the pool/spa sensor is above the
"Desired Temperature" setting.
To test the system, move the switch to “MANUAL TEST” and verify that both the
“Heating” and “Cooling” indicators light and that the valve(s) are in the solar loop
position. Move the switch to “MANUAL OFF” and verify that all indicators except
“Power” are off. The valve(s) should be in the normal recirculating loop position. If
the valve(s) positions are working in reverse, follow the instructions in section marked
“Low Voltage (LV) : Solar Valve” to correct. WARNING: If recirculate freeze
protection is being used, do NOT leave the switch in the “MANUAL OFF” position
during cold weather. Also note that the switch does NOT turn power off to the GL-
235.
GL-235 high voltage output used for Booster Pump
Figure 4
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Page 6
Basic Installation of GL-235
GL-235 high voltage output used for Timer Override
Figure 2
6 7
Figure 3
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