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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.
Description
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 So-
lar 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
2