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Jandy
®
JXi
™
Gas-Fired Pool and Spa Heater | Installation & Operation Manual
9.1.1 Saturation Index
PH, Total Alkalinity (TA), temperature, Calcium
Hardness and Total Dissolved Solids (TDS) play a
role in whether the water is either corrosive or scale
forming. These factors are combined in the Langelier
Saturation Index, which is a method for determining
whether or not water is properly balanced. See Table
8 below.
Saturation Index = pH + AF + CF + TF -12.1*
A-Factor=(AF), C-Factor=(CF), T-Factor=(TF)
Total Alkalinity Calcium Hardness Temperature
A-Factor C-Factor T-Factor
PPM
Factor
Value
PPM
Factor
Value
°F
Factor
Value
5 = 0.7 5 = 0.9 32 = 0.0
25 = 1.4 25 = 1.0 37 = 0.1
50 = 1.7 50 = 1.3 46 = 0.2
75 = 1.9 75 = 1.5 53 = 0.3
100 = 2.0 100 = 1.6 60 = 0.4
150 = 2.2 150 = 1.8 66 = 0.5
200 = 2.3 200 = 1.9 76 = 0.6
300 = 2.5 300 = 2.1 84 = 0.7
400 = 2.6 400 = 2.2 94 = 0.8
800 = 2.9 800 = 2.5 105 = 0.9
A saturation index of 0 is perfectly balanced
A negative saturation index has corrosive tendencies
A positive saturation index has scaling tendencies
A saturation index of +0.3 or -0.3 is ideal
*-12.1 should be changed to -12.2 if Total Dissolved Solids (TDS)mea-
sure at 1,000 ppm or greater
Table 8. Water Saturation Index
The practice of putting tablet-based sanitizer in the
skimmer basket can produce heavily chlorinated
water with very low pH. If this comes in contact
with metal parts of the heater it can cause serious
damage. Practices like this should be discontinued.
If acidic conditions are present, there could be signs
of metal in the pool water that could cause staining
on the floor of your pool. This might manifest itself
in the form of brown stains on the finish of your
pool bottom or pool water discoloration. Your local
pool dealer can test for metals in your water or can
provide you with a test kit.
Every effort should be made to maintain the water
balance of your pool or spa in the proper range.
Ignoring this very important component of your
pool’s water chemistry can make the water less
enjoyable to bathe in and result in permanent
damage to your heater and/or complete failure of
individual components.
Zodiac Pool Systems LLC does not warrant heat
exchangers damaged by corrosive water issues or
from the build-up of calcium in the heater’s heat
exchanger. Any questions regarding proper water
balance can be directed to our product support line
at Zodiac
®
or to your local pool dealer.
NOTE: The Thermal Regulator Valve (TRV) is an indicator
of how well the water balance is being maintained.
The TRV should be inspected before each
pool season to ensure it is clean and operating
properly. If you see signs of calcium buildup
(scale-forming or base water) or corrosion (acidic
water) the TRV should be replaced and your water
balanced.
9.2 Swimming Pool Energy Saving Tips
Please review the following recommendations
to help conserve fuel and minimize the cost of
operating your pool heater without sacrificing
comfort.
• The American Red Cross
®
recommends a
maximum water temperature of 78°F (26°C). Use
an accurate pool thermometer. A difference of 4°F
(2°C), between 78°F and 82°F (26°C and 28°C),
will use as much as 40% more gas.
• Carefully monitor the water temperature of your
pool in the summertime. You can reduce heater
usage due to warmer air temperatures.
• Find the proper setting on the pool heater
temperature control and use the Set Point
Lockout feature to discourage further
adjustments.
• Set the pump time clock to start the pump no
earlier than 6:00 AM. This is the time when nightly
heat loss balances.
• If the pool is only going to be used on weekends,
reduce the heater temperature control setting by
8 or 10 degrees during the week. Reset it to the
78°F (26°C) level a day or so before you plan to
use the pool.
• During the winter or when on vacation for longer
than a week, shut down the heater by following
the shutdown instructions found in Section 8.6
and Figure 20 and on the inside of the heater.