LAARS Mighty Therm AP (Sizes 500-1825) - Installation, Operation and Maintenance Instructions - Manual (Page 13)

Mighty Therm Commercial Pool Heating Boiler Page 13
2. Manual Hi-Limit Checkout. The manual high limit
capillary bulb is installed at the heater outlet. (This
is not the auto reset high limit installed in the pool
return line). For spas see Section 3.9. The manual
reset high limit is factory preset to 150°F (66°C).
Confi rm this set point on the unit and adjust if
necessary. After running the heater in a fi ring mode
for 10 minutes, slowly close the outlet valve “B”
to raise the outlet temperature as indicated on the
outlet thermometer. The high limit should trip
within 2°F (1°C) or 3°F (2°C) of the 150°F (66°C)
setpoint and shut off the burners. If this does not
occur, adjust the set point on the unit to shut off the
burners when the outlet thermometer reads 150°F
(66°C). Open the outlet valve “B” and push the
reset button. The main burners should reignite.
3. Flow Switch: See attached vendor literature.
4. Low Water Cutoff (optional): See attached vendor
literature.
3.4 Inlet Temperature and Temperature
Rise
Adjustment
For proper operation the bypass and outlet valves must be
adjusted to obtain the correct heater temperature rise and
inlet water temperature. Use the following method to set
the bypass assembly at start up:
1. With all bypass valves open, fi re the heater for at
least 10 minutes. The operating control should
be set at least 5° to 10° F (2.8° to 6°C) above the
pool tem per a ture to ensure continued operation
through out this set up procedure.
2. Observe the thermometer on the inlet header. To
prevent condensation and damage to the heater, the
inlet water temperature has to be 110°F (43°C).
If the inlet temperature is LESS THAN
110°F (43°C): With the bypass valve
“A” fully open, throttle (turn down) outlet
valve “B” slightly. Observe the inlet
thermometer for 5 minutes to see where the
inlet tem per a ture stabilizes. If it remains
under 110°F (43°C), throttle outlet valve “B”
a little more. Repeat as necessary. If the
inlet tem per a ture rises above 110°F (43°C),
open outlet valve “B” slightly until the inlet
temperature stabilizes as close to 110°F as
possible (plus or minus 2°F (1°C)).
If the inlet temperature is MORE THAN
110°F (43°C): If outlet valve “B” has been
throt tled partially closed, open it slightly, wait
5 minutes, and, if the temperature is not down
to 110°F (43°C) (plus or minus 2°F (1°C))
open it some more. If bypass valve “B” is
fully open and you are still seeing inlet water
temperatures in excess of 110°F (43°C), you
can adjust bypass valve “A”. Throttle it (turn
down) slightly towards closed, and wait until
the inlet water temperature stabilizes again.
Repeat as necessary.
When the inlet temperature is stabilized at 110°F
(43°C), either lock the valve handles, remove them,
or prom i nent ly mark them to prevent tampering or
accidental changes to the valve positions.
If the pool water temperature needs to be raised
more than 10° F (5°C) to reach a comfortable
swim ming temperature, inspect and re-adjust the
valves twice a day to maintain the 110°F (43°C)
inlet water temperature.
3. To prevent nuisance high limit tripping, set the
adjustable pump time delay relay to 10 minutes
for all models. This allows the heater pump to
circulate water through the heat exchanger after the
burners shut off, recovering all residual heat in the
metal components.
4. The heater outlet temperature with the bypass
adjusted as detailed above should be less than
142°F (61°C). The normal range will be 10 to 37°F
(5° to 18°C) higher than the inlet temperature. If it
exceeds 142°F (61°C), please contact the Service
Department at 800-900-9276 for in struc tions.
Outlet temperatures in excess of 142°F (61°C) may
cause intermittent high limit tripping.
POOL OPERATING CONTROL ADJUSTMENT:
5. Adjustable Differential Feature: Remove the cover
from the control box and verify that the white
differential potentiometer is set at about 2°F
(1°C). NOTE: a 2°F
(1°C) differential means that,
if the thermostat is set at 80°F (27°C), the heater
will come on at 78°F (25°C) and go off when the
pool reaches 80°F (27°C). The 2°F (1°C) value is
a good starting point for most installations. This
differential may be adjusted up or down to suit
individual applications.
6. The operating control temperature setting can be
adjusted incrementally to obtain the desired pool
operating temperature.
7. An adjustable pump time delay relay is mounted in
the control panel (see Figure 11). This relay keeps
the pump running after the burners shut off. The
delay should be set to 10 minutes.
3.5 Heater Shut Down
1. If heater is fi ring, turn operating control to lowest
value, wait 10 minutes for pump to stop running,
then turn power switch to off.
2. If heater is not fi ring, turn power switch to off.
3.6 Spring and Fall Operation
Standby
Service
Turn the thermostat down to approximately
70°F (21°C). This will prevent the pool and surrounding
ground from becoming chilled and also permit the pool to
be raised to swimming temperature in a shorter time.