After Start-Up Checking Water Flow; After Start-Up / Spring, Fall And Winter Operation - Pentair MT125 Installation And User Manual

Section 4. Maintenance
58
AFTER START-UP
CHECKING WATER FLOW
Fire or flooding hazard. If the unit overheats and the burner fails to shut off, follow instructions under "To Turn Off Gas to the
Appliance", page 43, and call a qualified service technician to repair unit.
After start-up, the outlet water pipe should feel slightly warmer than the inlet pipe. If it feels hot, or if you hear the water in the heater
boiling, there may not be enough water flow to the appliance. Make sure that the filter is not plugged. If water temperature remains
high but the unit continues to operate, turn off the appliance and call your service technician.
SPRING AND FALL OPERATION
If the pool is only used occasionally, lower the pool thermostat to 20° C (68° F) and leave the heater on. This will keep the pool and
the surrounding ground warm enough so that the heater should restore the pool to a comfortable temperature within about one day.
WINTER OPERATION
• Operating this heater continuously at water temperatures below 20°C (68°F) will cause harmful condensation and will
damage the heater and void the warranty.
• If the heater has been drained for freezing condition, do NOT turn "ON" until the system is circulating water.
• Water trapped in the heat exchanger can result in freeze damage to the exchanger or headers. Freeze damage is specifically
not covered by the warranty.
• When starting the heater for the swimming season with a water temperature below 10°C (50° F), the heater may be used
to heat the water; however, make sure that the heater operates continuously until the water temperature reaches the
heater's minimum setting of 20°C 68°F). During cold weather, if there is no danger of freezing, operate the filter pump
continuously even if the heater is not operating. If air temperatures are expected to drop below freezing (0°C / 32°F), shut
down the heater and winterize it.
For outdoor heaters in freezing climates, shut the heater down and drain it for winter as follows:
1. Turn off electrical supply to the heater and pump.
2. Close main gas control valve and manual gas valve (located outside the heater). Turn switch on heater gas valve to OFF.
3. In colder climates where they may be required, open drain cock located on the bottom of the manifold adapter, and drain the
heat exchanger and manifold adapter completely. If heater is below pool water level, be sure to close isolation valves to prevent
draining the pool (isolation valves are not required and should not be used on heaters installed above pool water level except
when needed for winterizing valves). Assist the draining by blowing out the heat exchanger through the pressure switch fitting
with low pressure compressed air (less than 35 kPa or 5 PSI).
Explosion hazard. Purging the system with compressed air can cause components to explode, with risk of severe injury or death
to anyone nearby. Use only a low pressure (below 5 PSI or 35 kPa), high volume blower when air purging the heater, pump,
filter, or piping.
4. Remove the Water Pressure Switch. Plug the port in the manifold to prevent bugs and dirt from getting into the manifold.
5. Drain the plastic inlet/outlet manifold through the outlet pipe. If the pipe does not drain naturally to the pool, install a drain cock
in the outlet pipe to drain the manifold.
6. Cover air inlet grate with a plastic bag to prevent bugs, leaves, etc., from getting into the heater.
NOTICE: Water trapped in the heater can cause freeze damage. Allowing the heater to freeze voids the warranty.
To return the heater to service after winterizing:
1. Connect the INLET and OUTLET unions to the system plumbing. Check that they are connected correctly and there are no water
leaks.
2. Before starting the heater, circulate water through the heater for several minutes until all air noises stop. See also "BEFORE
START-UP" (page 42) and "CARE AND MAINTENANCE" (page 57).
(See additional notes under Important Notices in Introduction.)
MASTERTEMP 125 Pool and Spa Heater Installation and User's Guide
WARNING
CAUTION
WARNING
460906 Rev. D 8/2020