Rheem Raypak AVIA 264 Installation And Operation Manual page 22

NOTE: To avoid water damage or scalding due to valve
operation, drain pipe must be connected to the outlet of
the PRV 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.
The heater requires water flow and positive pressure to
fire and operate properly. It must therefore be installed
downstream of the discharge side of the filter pump. See
Figure 24 and Figure 25.
A typical installation is plumbed as follows:
1. The inlet side of the filter is plumbed directly to the
discharge side of the filter pump;
2. The outlet side of the filter is then plumbed to the inlet
of the heater; and
3. The outlet of the heater is plumbed to the return line
to the pool or spa. The pump, filter and heater are
thus plumbed in series (Salt generators and chemical
feeders must be downstream of the pool heater).
A CAUTION: An additional source of heated water,
e.g. a solar heating system, must be connected to the
main line ahead of the heater inlet pipe in order for it
to act as the primary heat source. If the primary system
provides adequate heat to maintain setpoint, the heater
will not fire. Be advised that the control panel will then
display sensed water temperatures downstream of the
primary heating system, rather than the temperature of
the water exiting the pool.
Heater must be located so that any water leaks will not
damage the structure of adjacent area. CPVC or PVC pipe
may be glued directly into the half-unions provided.
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