Filter
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Model LG & LD Pool and Spa Heater
Page 13
• When chemical feeders are used, plumb the
feeder downstream of the heater and install an in-
line check valve between the heater and the feeder
(a minimum of 18" is required between the heater
and the check valve).
• Never deposit chemicals directly in the pool
skimmer.
2G-4a. Water Chemistry
Proper chemical balances are necessary for
sanitary bathing conditions as well as ensuring your
heater's long life. Be sure to keep your chemical levels
within the values indicated in Table 7. Waterpik
Laars does not warrant heat exchangers damaged
by corrosive chemical levels or excess dissolved
solids in pool or spa water.
For spas, it is also necessary to perform water
changes in addition to chemical treatment. It is recom-
mended to change the spa water every 60 days for light
usage and every 30 days if usage is heavy.
2G-6. Adjusting the Pressure Switch
Caution
The pressure switch should be adjusted to turn
the heater off when the pump is off. Setting
the switch to close at too low of a flow can
damage the appliance. Adjust the switch to
turn the heater off, not on.
The pressure switch is preset at the factory for
activation at 2 psi (14 kPa). Adjust the pressure switch
only if any part of the filter system piping is 3 feet
(0.91 m) or more above the top of the heater jacket.
Do not adjust the pressure switch if the heater is
installed more than 15 feet (4.57 m) below or 6 feet
(1.83 m) above the pool surface. Consult your local
Waterpik Laars representative for recommendations.
On some installations, the piping from the heater
to the pool is very short. The back pressure could be
too low to trigger the pressure switch. If this happens,
it may be necessary to install a directional fitting or
elbows where the return line enters the pool. This will
increase back pressure enough for the heater to operate
properly.
Make sure the pool filter is clean before making
any pressure switch adjustment: A dirty filter will
restrict the water flow and the pressure switch cannot
be adjusted properly. To adjust the pressure switch:
1. Set the control panel rotary switch (LD) or the
control panel rocker switch (LG) to the OFF
position (see Figure 18).
2. Set the Pool temperature control to the Max
position.
3. Turn filter pump on. If a two-speed pump is used,
make sure it is at high speed.
Table 7. Mineral Concentration Levels
Test Recommended Level
Free chlorine 1.0 to 3.0 ppm
Bromine 3.0 to 5.0 ppm
pH 7.2 to 7.8
Total alkalinity (TA) 80 to 120 ppm
Calcium hardness (CH) 200 to 400 ppm
Langelier saturation index (LSI) -0.5 to +0.5
Total dissolved solids (TDS) Less than 2000 ppm
Cyanuric acid 30 to 150 ppm
Copper 0 ppm
2G-5. Pressure Relief Valve
A pressure relief valve is not furnished with the
Laars Lite 2 heater. However, it is recommended that a
pressure relief valve be installed and may even be
required by local codes.
To install a pressure relief valve, remove the 3/4
inch (19 mm) brass plug located on the top of the inlet/
outlet header (see Figure 17). Install the pressure relief
valve in the threaded hole from which the plug was
removed. The pressure rating of the valve should be at
or below the lowest working pressure of any compo-
nent in the filter system. Any pressure relief valve
installed must comply with provisions of the Standard
described in ANSI Z21.22 for the United States, or
CAN1-4.6 in Canada.
Figure 17. Thermometer and pressure relief valve.