Filter
Top Products
LX and LT Pool Heaters
Page 17
To adjust the pressure switch, proceed as follows (see
Figure 19).
The pool filter must be clean before making this
adjustment. The heater does not have to be firing.
1. Set the heater control to the "OFF" position.
2. Start the filter pump and confirm by means of an
voltmeter that the pressure switch closes (if the
switch fails to close, replace it with a switch which
has a lower minimum setting).
3. Set the heater control to either 'Pool' or 'Spa'. Heater
should start.
4. Pry out the top rubber dirt plug on the pressure
switch.
5. Use a 7/32 inch Allen wrench to turn the adjustment
screw very slowly clockwise until the heater goes off.
6. Slowly turn the pressure switch adjustment screw
counterclockwise one-quarter turn. The heater
should come back on.
7. Check the adjustment by turning the filter pump OFF.
The heater fan will continue to run but the burners
should shut off immediately. If they do not, restart the
filter pump and repeat Steps 6 and 7. Check the
adjustment again.
8. Return the pool temperature control to the desired
temperature.
It may be necessary to repeat these steps to get a
proper setting. The switch must be set so that the heater
will not fire unless the pump is running. If a proper setting
cannot be reached, contact the factory service department.
2J-5. Water Temperature Rise
The Laars LX and LT pool heaters have an internal
bypass which accommodates a wide range of water flow.
The bypass is easily adjustable to change the temperature
rise for optimum performance and length of heater life.
The bypass assures constant heat exchanger flow even
though flow through the filter system will vary depending
on how dirty the filter is.
For most installations, an external bypass valve is
not needed in the heater water piping. This is due to the
large size of the heater's internal bypass valve. If the pump
flow rate is known to significantly exceed 125 gpm
(7.9 l/s), an external bypass may be needed to assure
proper heater operation.
Water flow should be confirmed upon start-up of the
heater and in most servicing situations. If the flow is not
normal, corrections must be made to the pool system. Flow
is evaluated by determining the water temperature rise
through the heat exchanger.
Before checking the temperature rise, make sure that
the pool filter is clean. If necessary, clean all components
of the filter system. Temperature rise is measured in the
outlet of the far-right tubes when facing the inlet/outlet
water heater. To measure the temperature rise, turn off the
filter pump and remove the plastic plug to the right of, and
just below the level of the outlet water pipe. This is
mounted flush with the heater jacket (See Figure 20). With
the plug removed, install the special thread adapter and
"Petes" plug fitting and insert a pocket thermometer.
The internal bypass can be adjusted by means of a
screw on the right hand side of the header. To adjust the
temperature rise to within the ranges specified in table 8,
proceed as follows.
1. If the piping system has an external bypass valve,
close it.
2. Set the heater's control panel to the "Off" position.
3. Start the filter pump.
4. After three minutes, note and record the thermometer
reading. This is the pool water temperature.
Pry off cap
to adjust
Figure 19. Adjustment of Pressure Switch.
THERMOMETER
WITH PETE'S
PLUG
Figure 20. Temperature Rise Measurement
BYPASS
ADJUSTMENT
SCREW