Model DP Oil-Fired Heater
Page 19
6.
Check the adjustment by turning the filter pump
OFF. The heater's burner should shut off
immediately. If it does not, restart the filter pump
and repeat Steps 5 and 6. Check the adjustment
again.
7.
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 fire unless the pump is running. If a
proper setting cannot be reached, contact the factory
service department.
7.7 Temperature Rise
The Laars XL-3 pool and spa heater has an
internal bypass which accommodates a wide range of
water flow. The bypass assures constant heat
exchanger flow even though flow through the filter
system will vary depending on how dirty the filter 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 flow rate is known to significantly exceed
60 gpm (3.8 l/s), an external bypass will be needed to
assure proper heater operation.
Water flow should be confirmed upon start-up of
the heater and in most servicing situations. If the flow
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 filter is clean. If necessary, clean all
components of the filter system. Temperature rise is
measured in the outlet of the far-right tubes when
facing the inlet/outlet water heater. To measure the
temperature rise, turn off the filter pump and remove
the 1/4" brass plug to the right of, and just below the
level of the outlet water pipe. This is mounted flush
with the heater jacket (see Figure 19). With the plug
removed, install the special thread adapter and
"Petes" plug fitting and insert a pocket thermometer.
A temperature rise measurement kit is available
through your Jandy distributor. See section 10 of this
manual for the correct kit number.
Use the following procedure to adjust the
external bypass valve to assure proper water flow
through the heat exchanger.
1.
Clean the filter.
2.
Install a thermometer in the 1/4" NPT threaded
opening in the front header casting as shown in
Figure 19.
3
Close the manual bypass valve.
4.
Set the heater's control to the "OFF" position.
5.
Start the filter pump.
6.
After three minutes, note and record the
thermometer reading. This is the pool water
temperature.
7.
Start the heater by setting the control to the "ON"
position and set the thermostat high enough to
call for heat. Allow the heater to operate for five
minutes or more. Note and record the
thermometer reading. Subtract pool water
temperature from this reading. This difference is
the temperature rise. If your measured
temperature rise is within the range of 16° to
20°F (8.9° to 11.1°C), skip step 8.
8.
Gradually open the manual bypass valve until the
temperature rise falls within the range of 16° to
20°F (8.9° to 11.1°C)
9.
After obtaining the correct temperature rise,
scribe a line on the bypass shaft and case to
mark the correct adjustment position. Wire or
remove the valve handle to prevent tampering.
If temperature rise is too high, there is inadequate
flow, possibly requiring a change to the piping system
or a larger pump. Before proceeding with any
changes, verify proper heater operation. A problem
with the heater's internal bypass assembly will effect
measured temperature rise.
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
concentration 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.
Figure 19. Thermometer Placement.
