LXi
™
Pool/Spa Heater Installation and Operation Manual Page 37
ture from this reading. This difference
is the temperature rise. Refer to Table 7.
If your measured temperature rise is within the
range designated for your heater, skip steps
6 through 8.
6. Locate the bypass adjustment screw on the right-
hand side of the header. (See Figure 33.) Loosen
the nut so that the screw can be adjusted. A slight
water leak past the nut may be expected. Turn the
screw counterclockwise to decrease the tempera-
ture rise, and clockwise to increase the tempera-
ture rise as needed to achieve the ranges in
Table 7. After the adjustment, tighten the nut so
that no leaks occur.
7. If the temperature rise is too low and cannot be
raised by means of the adjustment screw, the fl ow
is in excess of 125 GPM (7.9 lps). An external
bypass will need to be installed, or if one already
exists, open the external bypass valve gradu-
ally until the temperature range in Table 7 is
achieved.
8. If it was necessary to adjust the external bypass
as outlined in step 7, scribe a line on the bypass
shaft and case to mark the correct adjustment
position. Wire or remove the valve handle to
prevent tampering.
Table 7. Water Temperature Rise and Flow Rates
(Measured at Return Header)
Model
Minimum
Temp Rise,
°F (°C)
Maximum
Temp Rise,
°F (°C)
Minimum
System Flow
GPM (lps)
250 7 (4) 10 (6) 30 (1.9)
300 8 (4) 11 (6) 30 (1.9)
400 13 (7) 17 (9) 30 (1.9)
In a system without external bypass, it may be
necessary to make changes. If temperature rise is too
low, a manual bypass must be installed. If tempera-
ture rise is too high, there is inadequate fl ow, possibly
requiring a change to the piping system or a larger
pump. Before proceeding with either remedy, verify
proper heater operation. Low gas input results in low
temperature rise and vice-versa. A problem with the
heater internal bypass assembly also affects measured
temperature rise.
7.9 Burner Throat Pressure Adjustment
The burner throat pressure should be adjusted
using the air orifi ce on the intake of the fan. This air
orifi ce has a slider attached to it. This slider is used to
increase or decrease air pressure. The air pressure will
drop as more of the slider covers the air orifi ce. The
air pressure will increase as more of the air orifi ce is
exposed. The pressure should be adjusted to 1.0" WC.
See Section 10.4.
Section 8. Maintenance
8.1 Water Chemistry
The mineral content of swimming pool water
increases daily due to natural evaporation and the addi-
tion of sanitizing chemicals. If the mineral concentra-
tion in the pool gets too high, the excess minerals will
deposit on the walls of the pool, in the fi lter system,
and in the heater tubes.
The proper chemical balance in spa water is more
critical than in a swimming pool heater operation. Due
to the spa’s size, high water temperature and heavy
usage, chemical values in a spa can vary greatly. This
chemical imbalance can result in unsanitary water
conditions, and affect the life of the heater.
Proper chemical balances are necessary for
sanitary bathing conditions as well as ensuring your
heater's long life. Kits are available from your local
pool supply dealer for making the various tests for
mineral content. One of these kits will detect copper
in the system. This is usually a warning that corrosion
is taking place, possibly due to a low pH value com-
bined with other chemistry problems. The condition
can be corrected by changing the spa water and closely
monitoring the pH factor and chemical properties of
the water. Be sure to keep your chemical levels within
the values indicated in Table 8. Jandy Pool Products,
Inc. 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.
Table 8. Optimal Water Chemistry Ranges*
Test Recommended Level
Free Chlorine 1.0 to 3.0 ppm
Bromine 2.0 to 4.0 ppm
pH 7.2 to 7.8 (Ideal range is 7.4 to 7.6)
Total Alkalinity (TA) 80 to 120 ppm
Calcium Hardness (CH) 175 to 400 ppm
Cyanuric Acid 50 to 75 ppm
Total Dissolved Solids
(TDS)
1000 to 2000 ppm (Excluding dis-
solved NaCl from a Salt Chlorine
Generator)
Copper 0 ppm
* Concentration levels taken from Basic Pool and Spa
Technology published by APSP (Association of Pool and Spa
Professionals).
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