Maintenance; Pressure Relief Valve; Spring And Fall Operation - Winter Operation - Pentair Pool Products MiniMax NT Series Service Manual

Maintenance

It is recommended that you check the following items at least
every six months and at the beginning of every swimming
season.
1. Examine the venting system. Make sure there are no
obstructions in the flow of combustion and ventilation air.
2. Visually inspect the main burner and the hot surface
ignitor. The normal color of the flame is blue. When flame
appears yellow, burners should be inspected and cleaned.
Check ignitor for damage.
3. Inspect the heat exchanger for soot. Clean as necessary.
4. Remove burner tray and clean burners and main burner
orifices.
5. Keep the heater area clean and free from combustibles
and flammable liquids.
6. Check wire ends and wire connections. They should be
clean and tight.
7. Check the gas pressure as described in this manual.
STANDARD
Figure 21.
SPRING AND FALL OPERATION
If the pool is being used occasionally, do not turn the heater completely off. Set the thermostat down to 68° F. This will keep the pool
and the surrounding ground warm enough to bring the pool up to a comfortable swimming temperature in a shorter period of time.
WINTER OPERATION
OPERATING THIS HEATER CONTINUOUSLY AT WATER TEMPERATURE BELOW 68° F. WILL CAUSE HARMFUL
CONDENSATION AND WILL DAMAGE THE HEATER AND WILL VOID THE WARRANTY.
If the pool won't be used for a month or more, turn the heater off at the main gas valve. For areas where there is no danger of water
freezing, water should circulate through the heater all year long, even though you are not heating your swimming pool. The MiniMax NT
Series should not be operated outdoors at temperatures below 0° F. for propane and -20° F. for natural gas. Where freezing is
possible, it is necessary to drain the water from the heater. This may be done by opening the drain valve, located at the inlet/outlet
header, (see Figure 22.), allowing all water to drain out of the heater. It would be a good practice to use compressed air to blow the
water out of the heat exchanger.
• 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.
Rev. B 2-11-04
REMOVE THE FLOW VALVE ASSEMBLY WHEN
DRILLING THE HOLE TO INSTALL A PRV, OTHERWISE,
YOU WILL DRILL INTO THE VALVE ASSEMBLY.

PRESSURE RELIEF VALVE

In some installations, a pressure relief valve (PRV) is required
on the MiniMax NT Series.
To install a PRV, carefully
drill a 3/8 in. hole in center
of 3/4 in. NPT port (on
main header) being careful
to drill only through wall at
bottom of 3/4 in. NPT port
and no deeper—now thread
in the 3/4 NPT PRV.
NOTE: (A.S.M.E. version
varies slightly. It is of
bronze construction, and is
supplied with the A.S.M.E.
Section IV, pressure relief
valve pre-installed at factory.)
Test the relief valve at least
once a year by lifting up
lever.
LOW-NOx
CAUTION
CAUTION
CAUTION
REMOVE FLOW VALVE
BEFORE DRILLING
THE NPT PORT
A.S.M.E. VERSION
P/N
25
RELIEF
VALVE
FOR PRV
INSTALLATION
DRILL THRU
THE NPT PORT
Figure 22.
RELIEF VALVE
TO WINTERIZE,
OPEN DRAIN VALVE
NTSM03