Below Pool Installation; Flow Switch - Pentair MASTERTEMP 125 Guide D'installation Et D'utilisation

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 70 GPM (265 LPM),
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 5.
Model Min. (GPM) (LPM) Max. (GPM) (LPM) *
125 20 (76)
* Do not exceed the maximum recommended flow
rate for the connecting piping.
Table 1.
See page 34 for Pressure Relief Valve Installations.

BELOW POOL INSTALLATION

If the heater is below water level, the pressure switch must be ad-
justed. This adjustment must be done by a qualified service techni-
cian. See following CAUTION before installation.
The water pressure switch is set in the factory at 3.00 PSI (± 0.75 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 34, Figure 29.
If the heater is installed more than 5' above the pool or more than 4' below the pool level, you will be beyond the limits
of the pressure switch and a flow switch must be installed. 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 in place of the water pressure
switch wires.
Rev. C 3/2019
CAUTION
70 (265)
CAUTION
BELOW OR ABOVE POOL INSTALLATION

FLOW SWITCH

MASTERTEMP 125 Pool and Spa Heater Installation and User's Guide
Section 3. Installation Instructions
Cool water in
1. Set Manual By-Pass Valve.
2. Remove Handle.
INLET FROM HEATER
13
Warm water out
OUTLET TO POOL
Figure 5.