Valves; Manual By-Pass; Below Pool Installation - Pentair MASTERTEMP 125 Installation And User Manual

VALVES

When any equipment is located below the surface of the pool or spa, valves should be placed in the circulation piping
system to isolate the equipment from the pool or spa. Check valves are recommended to prevent back-siphoning.
Back-siphoning is most likely to occur when the pump stops, creating a pressure-suction differential. Do NOT sanitize the
pool by putting chlorine tablets or sticks into the skimmer(s). When the pump is off, this will cause a high concentration
of chlorine to enter the heater, which could cause corrosion damage to the heat exchanger.
Exercise care when installing chemical feeders so as to not allow back siphoning of chemical into the heater, filters or
pump. When chemical feeders are installed in the circulation of the piping system, make sure the feeder outlet line is
down stream of the heater, and is equipped with a positive seal noncorrosive "Check Valve", (P/N R172288), between
the feeder and heater.

MANUAL BY-PASS

Where the water flow rate exceeds the maximum 454 L/m, a manual
bypass should be installed and adjusted. After installing the valve, adjust
the valve to bring the flow rate within the acceptable range. Then remove
the valve handle or lock it in place to avoid tampering. See Figure
Model Min. L/m (GPM)
125 76 (20)
* DO NOT EXCEED THE MAXIMUM RECOMMENDED FLOW RATE
FOR THE CONNECTING PIPING.
Table 1.
See page 39 for Pressure Relief Valve installation.

BELOW POOL INSTALLATION

If the heater is below water level, the pressure switch must be adjusted. This adjustment must be done by a qualified
service technician. See following CAUTION before installation.
The WATER PRESSURE RELIEF VALVE SWITCH is set in the factory at 0.20 bar (3.00 psi). This setting is for a heater
installed at pool level. If the heater is to be installed more than 1' above or below, the water pressure switch must be
adjusted by a qualified service technician. See page 39.
If the heater is installed more than 1.5 m above the pool or more than 1.2 m below the pool level, which is beyond the
limits of the heater's pressure switch specification. In this case, a flow switch must be installed in the heater. Locate
and install the flow switch externally on the outlet piping from the heater, as close as possible to the heater. Connect
the flow switch wires as used for the water pressure switch.
P/N 475114 Rev. F 8/2020
CAUTION
(WATER FLOW RATE)
Max. L/m (GPM) *
265 (70)
CAUTION
BELOW OR ABOVE POOL INSTALLATION
FLOW SWITCH INSTALLATION
MASTERTEMP 125 Pool and Spa Heater Installation and User's Guide
Section 1. Installation
7.
1. Set Manual By-Pass Valve.
2. Remove Handle.
Figure 7.
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Warm water out
Cool water in
INLET FROM HEATER
OUTLET TO POOL