Plumbing Connections; Valves; Manual By-Pass; Water Connections - Pentair MASTERTEMP 125 Guide D'installation Et D'utilisation

Section 3. Installation Instructions
12

PLUMBING CONNECTIONS

125 heater has the unique capability of
The MasterTemp ®
direct schedule 40 PVC plumbing connections. A set of
bulkhead fittings is included with the MasterTemp® 125
heater to insure conformity with Pentair's recommended
PVC plumbing procedure. Other plumbing connections can
be used. See Figure 3 for plumbing connections.
CAUTION
Before operating the heater on a new installation, turn on
the circulation pump and bleed all the air from the filter
using the air relief valve on top of the filter. Water should
flow freely through the heater. Do not operate the heater
unless water in the pool/spa is at the proper level. If a
manual by-pass is installed, temporarily close it to insure
that all air is purged from the heater.

WATER CONNECTIONS

The heater requires proper water flow and pressure for its
operation. See Figure 4 for the recommended installation. The
filter pump discharges to the filter, the filter discharges to the
heater, and the heater discharges directly to the pool or spa.
A manual bypass valve should be installed across the heater
when the pump flow exceeds 70 GPM (265 LPM ) . See
"WATER FLOW RATE" Table 1 on
the manual by-pass valve.
Make sure that the outlet plumbing from the heater contains
no shut-off valves or other flow restrictions that could prevent
flow through the heater (except for pool installations as noted
below, or winterizing valves where needed). To switch flow
between the pool and spa, use a diverter valve. Do not use
any valve that can shut off the flow.
Install the chemical feeder downstream of the heater. Install a chemical resistant one-way check valve between the
heater and the chemical feeder to prevent back-siphoning through the heater when the pump is off.
NOTICE: If the heater is plumbed in backwards, it will cycle continuously. Make sure piping from filter is not reversed
when installing heater.
Connect the heater directly to 1.5" PVC pipe, using the integral unions provided. Heat sinks are not required. The low
thermal mass of the heater will prevent overheating of the piping connected to the pump even if the heater shuts down
unexpectedly. If you are using a flexible corrugated hose for aboveground systems, use only Pentair approved flexible
hose kits: P/N 155151 (6 ft.) and P/N 155005 (12 ft.).
Occasionally a two-speed pump will not develop enough pressure on the low speed to operate the heater. In this case, run
the pump at high speed only to operate the heater. If this does not solve the problem, do not try to run the heater. Instead,
correct the installation.
Do not operate the heater while an automatic pool cleaner is also operating. If the circulation pump suction is plugged
(for example by leaves), there may not be adequate flow to the heater. Do not rely on the pressure switch in this case.
MASTERTEMP 125 Pool and Spa Heater Installation and User's Guide
page 13 for setting of
HEATER
FROM
FILTER
MANUAL
BY-PASS
Main
Drain
Pool
From Pool
3-Way
Valve
Figure 3.
TO
PUMP
POOL
FILTER
GATE
VALVE
FROM
POOL
3-Way
Chlorinator
Valve
Check Valve
Heater
Filter
Spa
Pump
3-Way
Valve
Figure 4.
Rev. C 3/2019