21
Internal Automatic Bypass Valve
In addition to the Unitherm Governor, a built-in automatic
bypass valve is provided in the In/Out header. While the
Unitherm Governor responds to the changes in water
temperature in the heater, the internal bypass 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.
BYPASS VALVE
BYPASS
SPRING
LOCK-NUT
BYPASS SHAFT
Figure 20. Internal Automatic Bypass Valve
External Auxiliary Bypass Valve
Where Required
- An auxiliary bypass valve should be
used when flow rates exceed 100 GPM (379 lpm). 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 below 50°F
(10°C). It also serves to eliminate needless pressure drop
through the heater and accompanying reduction in the flow
rate to the spa jets.
FROM HEATER
TO HEATER
TO POOL/SPA
FROM POOL/SPA
FULL PORT
BALL VALVE
OR GLOBE
VALVE*
BYPASS VALVE
*NOTE
: Do not use a gate valve.
Figure 21. Auxiliary Bypass Valve
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 comfortable to the
touch. If pipe is hot, close bypass; if cold, open bypass.
Pressure Relief Valve Installation
A 3/4" NPT connection is provided in the header for
installation of a pressure relief valve (PRV). The valve
shall be installed in a vertical position. The PRV can leak
overtime and may not operatre correctly if installed in a
different orientation. Do not over-tighten. Install pressure
relief valve hand-tight, plus a 1/2 turn. Use PRV kit
(018936F) and
Figure 23
below to properly plumb the
PRV.
ROUTE
PIPING
THROUGH
PORT
Figure 22. PRV Location
PRV VALVE
Figure 23. PRV Installed
Summary of Contents for AVIA 264A
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