MasterTemp Pool and Spa Heater P/N 474131 Rev. M 8/2020
14
Pool
Main
Drain
Spa
From Pool
3-Way
Valve
3-Way
Valve
3-Way
Valve
Chlorinator
Heater
Pump
Check Valve
Filter
WATER CONNECTIONS
The heater requires proper water ow and pressure for its
operation. See Figure 6 for the recommended installation.
The lter pump discharges to the lter, the lter 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 ow exceeds 454 LPM (120 GPM). See
“WATER FLOW RATE” Table 1 on page 12 for setting of
the manual by-pass valve.
Make sure that the outlet plumbing from the heater contains
no shut-off valves or other ow restrictions that could prevent
ow through the heater (except for below pool as noted below,
or winterizing valves where needed). To switch ow between
the pool and spa, use a diverter valve. Do not use any valve
that can shut off the ow. Do not use a shut-off valve to isolate
the heater unless it is below the level of the pool or spa.
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 lter is not reversed
when installing heater.
Connect the heater directly to 50 mm 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. 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 ow to the heater. Do not rely on the pressure switch in this case.
Local codes may require the installation of a pressure relief valve (PRV), see page 56 for “PRESSURE RELIEF
VALVE” instructions..
Figure 6.
Section 1. Installation
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