Unitherm Governor Operation; Internal Automatic Bypass Valve; External Auxiliary Bypass Valve - Raypak 266A Installation And Operation Manual

Follow the steps below to replace the ProTek Shield Assy:
1. Shut off the pool pump and bleed pressure from the
system.
2. Close isolation valves to minimize pool/spa water
loss.
3. Remove wing nut from bottom stud on ProTek Shield
Assy.
4. Remove bonding wire ring terminal from stud.
5. Rotate ProTek Shield Assy clockwise (by hand) to
unscrew it from the assembly.
6. Inspect/replace as necessary and reverse above
procedure to reinstall. Hand tighten only! Do not use
tools.
NOTE: Make sure the O-ring is properly seated in the
O-ring groove before installation.

Unitherm Governor Operation

A
CAUTION: The patented Unitherm Governor is
a thermostatic mixing valve specifically designed to
maintain constant heater internal temperature between
105°F (41°C) and 115°F (46°C) despite continually
changing flow rates from the filter and changing pool
temperatures. This narrow range is needed to prevent
damaging condensation on the burners which will
occur if the heater runs for any length of time below
100°F (38°C). It is also needed to inhibit scale formation
in the tubes by maintaining temperatures well below
accelerated scaling temperatures.
UG PLUG
UNITHERM GOVERNOR
GASKET
Figure 24. Unitherm Governor - Polymer
UNITHERM
GOVERNOR
Figure 25. Unitherm Governor - Bronze
F10725
UG/BYPASS ASSY
F10642-2

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 DISC
SPRING
"YELLOW" - 206/266
"GREEN" - 336/406
Figure 26. Internal Automatic Bypass Valve - Bronze
NOTE: The Unitherm Governor and Bypass Valve Assy
are not individually-replaced components on ASME
units. If either needs to be replaced, the entire UG/
Bypass assy must be replaced. The "yellow" spring is
used on models 206A, 266A. The "green" spring is used
on models 336A, 406A.

External Auxiliary Bypass Valve

Where Required - An auxiliary bypass valve should be
used when flow rates exceed 100 GPM (378 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, etc.
FROM HEATER
TO POOL/SPA
BYPASS VALVE
Do not use gate valve.
Figure 27. Auxiliary Bypass Valve
UG/BYPASS ASSY
F10642-3
FULL PORT
BALL VALVE
OR GLOBE
VALVE
FROM POOL/SPA
19