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PRESSURE RELIEF VALVE INSTALLATION
To conform to local building codes, it may be necessary
to install a pressure relief valve. A 3/4" pressure relief
valve having a capacity equal to BTU/HR output of the
model to be installed is recommended for this heater. The
maximum acceptable pressure relief valve setting is 125
psi.
A 3/4" NPT connection is provided in the plastic header
for installation of a pressure relief valve. The valve shall be
installed in a vertical position. Do not over tighten. Install
pressure relief valve hand tight plus 1/2 turn.
POLYMER HEADER
Pressure Relief Valve
PRV Discharge
Connection
Inlet/Outlet Header
Fig. #2004
A 3/4" NPT connection is provided in the header for
installation of a pressure relief valve. The valve shall be
installed in a vertical position.
ASME HEADER
(Cast Iron)
NOTE: To avoid water damage or scalding due to valve
operation, drain pipe must be connected to valve outlet
and run to a safe place of discharge. Drain pipe must be
the same size as the valve discharge connection
throughout its entire length and must pitch downward
from the valve. No shutoff valve shall be installed
between the relief valve and the drain line. Valve lever
should be tripped at least once a year to ensure that
waterways are clear.
INTERNAL AUTOMATIC BY-PASS VALVE
In addition to the Unitherm Governor, a built-in automatic
by-pass valve is provided in the in/out header. While the
Unitherm Governor responds to the changes in water
temperature in the heater, the internal by-pass valve
automatically responds to changes in water pressure in
the piping system. Proper amount of water flow is
maintained through the heater under varying pressures
dictated by the conditions of the pump and filter.
EXTERNAL AUXILIARY BYPASS VALVE
(Where Required)
An auxiliary bypass valve should be used when flow rates
exceed 125 GPM (usually a high performance pump size
larger than two horsepower will exceed this flow rate).
This valve is required to complement the function of the
automatic bypass valve, particularly when starting the
heater in winter or early spring when the spa or pool
temperature is down below 50°F. It also serves to
eliminate needless pressure drop through the heater and
accompanying reduction in the flow rate to the spa jets,
etc.
From Heater To Heater
To Pool From Pool
AUXILIARY BYPASS VALVE
(DO NOT USE GATE VALVE)
PRV Discharge
Connection
Inlet/Outlet Header
Pressure Relief
Valve
Fig. # 8095.0
Fig. # 8150.0ss
Fig.#2003
AUXILIARY BYPASS VALVE ADJUSTMENT
To set bypass: With clean filter, adjustment is made by
feeling the inlet and outlet pipes at the heater. Outlet
pipes should be slightly warmer than inlet and comfort-
able to the touch. If pipe is hot, close bypass; if cold, open
bypass.
SPRING
BYPASS DISC
BYPASS
BODY