Temperature Rise - Jandy Legacy LRZM Installation And Operation Manual

Legacy
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 fi re unless the pump is running. If a
proper setting cannot be reached, contact the factory
service department.
7.6

Temperature Rise

NOTE A temperature rise measurement kit is needed
to perform this test, order part number
R0336000.
The Legacy pool and spa heaters have an inter-
nal bypass which accommodates a wide range of
water fl ow. The bypass is easily adjustable to change
the temperature rise for optimum performance and
length of heater life. The bypass assures constant heat
exchanger fl ow even though fl ow through the fi lter
system will vary depending on how dirty the fi lter 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 fl ow rate is known to exceed 125 gpm (7.9
l/s), an external bypass may be needed to assure proper
heater operation.
Water fl ow should be confi rmed upon start-up of
the heater and in most servicing situations. If the fl ow
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 fi lter is clean and that gas supply and
manifold pressures are correct. If necessary, clean
all components of the fi lter system. Temperature rise
THERMOMETER WITH
PETE'S PLUG
Figure 20. Temperature Rise Measurement
Model LRZM Pool/Spa Heater Installation and Operation Manual
™
BYPASS
ADJUSTMENT
SCREW
is measured in the return header of the Legacy. To
measure the temperature rise, turn off the fi lter pump
and remove the plastic plug protruding through the
cabinet on the return header side of the heater. See
Figure 20. With the plug removed, install the special
thread adapter and Pete's Plug
pocket thermometer. A temperature rise measurement
kit is available through your Jandy distributor. See
Section 11 of this manual for the correct kit number.
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 specifi ed in
Table 6, proceed as follows:
1. If the piping system has an external bypass valve,
close it.
2. Turn the heater control panel to OFF.
3. Start the fi lter pump.
4. After three minutes, note and record the
thermometer reading. This is the pool water
temperature.
5. Start the heater by turning the controller to ON.
Allow the heater to operate for fi ve minutes
or more. Note and record the thermometer
reading. Subtract pool water temperature from
this reading. This difference is the temperature
rise. Refer to Table 6. If your measured tempera-
ture 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 20). 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
6. 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 6 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.
Page 27
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