Adjusting The Manual Bypass Valve; Maintenance; Water Chemistry - Jandy LG125 Installation And Operation Manual

Model LG Pool and Spa Heater
5. Insert a pocket thermometer (see Figure 14)
through the Pete's plug into the header.
6. Turn the filter pump ON and wait 3 minutes. The
heater remains OFF. This allows water from the
pool to reach the heater.
7. Record the temperature indicated by the ther-
mometer (cold water).
8. Turn the heater ON following the lighting
instructions found on the inside of the heater.
9. Allow the heater to run for about 3 minutes.
Record the new temperature reading (heated
water).
10. Subtract the first temperature reading (cold
water) from the second temperature reading
(heated water). The difference between the two
readings is the temperature rise. The tempera-
ture rise should be within the range shown in
Table 6.
11. If the temperature rise is below the minimum
range indicated, two possibilities arise:
a. The supply gas volume is too low.
b. The system's water flow exceeds 125 GPM
(475 LPM), and requires a manual bypass valve
for proper operation (see Figure 7).
12. If the temperature rise is above the maximum,
there is not enough water flowing through the
heater. Check for clogging in the water filter or
restriction in the water pipes.
CAUTION
Operating the heater with the temperature rise
above maximum or below the minimum can
damage the heater and may void the warranty.
Table 6. Temperature Rise and Minimum Flow Rates
Minimum
Size GPM (LPM)
125 20 (76)
175 20 (76)
250 25 (95)
325 30 (114)
400 30 (114)
Minimum Maximum
°F (°C) °F (°C)
27 (15) 36 (20)
33 (19) 42 (24)
33 (19) 42 (24)
28 (16) 38 (21)
30 (17) 39 (22)
13. If the temperature rise is within the correct range,
complete the procedure as follows:
a. Turn heater OFF.
b. Wait 3 minutes, turn filter pump OFF.
c. Remove thermometer and Pete's plug.
d. Replace the drain plug.

7.7 Adjusting the Manual Bypass Valve

If a manual bypass valve is installed, use the
following procedures to adjust the bypass valve:
1. Clean pool filter.
2. Remove drain plug located on the inlet/outlet
header of the heater and replace it with a Pete's
plug.
3. Insert a pocket thermometer (see Figure 15)
through the Pete's plug into the header.
4. Close manual bypass valve.
5. Turn on the temperature control to the OFF
position.
6. Repeat steps 6 through 10 of the temperature
rise test (see Section 7.6).
7. If the temperature rise is below the minimum
stated in Table 6, open the manual bypass valve
until temp rise climbs between the min. and max.
range for your size heater. If the minimum
temperature rise stated in Table 6 cannot be
reached with the manual bypass fully open, then
the gas supply volume is too low.
8. If the temperature rise is above the maximum,
there is not enough water flowing through the
heater. Check for clogging in the water filter or
restriction in the water pipes.
9. Once the temperature rise is within the correct
range, safety wire the handle of the manual
bypass valve in place and tag the valve to
prevent change in the water flow.
SECTION 8.

Maintenance

8.1 Water Chemistry

The mineral content of swimming pool water
increases daily due to natural evaporation and the
addition of sanitizing chemicals. If the mineral concen-
tration in the pool gets too high, the excess minerals
will deposit on the walls of the pool, in the filter
system, and in the heater tubes.
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