14
High-temperature CPVC header flanges and header
flange nuts are available as an option. If there is any
possibility of back-siphoning when the pump stops, it
is recommended that a check valve (or valves) also be
installed in the system.
Internal Automatic Bypass Valve
A built-in automatic bypass valve is provided in the
In/Out header. The internal bypass valve automatical-
ly responds to changes in water pressure in the piping
system. The 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
An auxiliary bypass valve must be used when flow
rates exceed 70 GPM. Usually a high-performance
pump size larger than one 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. It also
serves to eliminate needless pressure drop through
the heater and accompanying reduction in the flow
rate to the spa jets, etc.
Bypass Disc
Spring
Bypass Body
Fig. 14: Internal Automatic Bypass Valve
From Heater
To Heater
To Pool/Spa
Bypass Valve
From
Pool/Spa
Full Port
Ball Valve
or Globe
Valve
Fig. 15: Auxiliary Bypass Valve
NOTE:
Do not use a gate valve as an 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 comfort-
able to the touch. If pipe is hot, close bypass; if cold,
open bypass.
Pressure Relief Valve Installation
To conform to local building codes, it may be neces-
sary to install a pressure relief valve. A 3/4" pressure
relief valve, having a capacity equal to the BTUH out-
put of the heater to be installed, is recommended for
this heater. The maximum pressure relief valve setting
is 125 psi. This relief valve needs to be installed on the
outlet pipe from the header as noted in Fig. 16 below.
Pipe onto Discharge Side of Piping
Fig. 16: Pressure Relief Valve Installed
