30 RIVA FP MANUAL
13. Circulator Sizing
13.1 Circulator capacity as a function of fl ow rate:
Figure 13.1
The hydraulic specifi cation in Fig 13.1 represent the pressure (available head for the
central heating system) as a function of the fl ow rate. The pressure loss due to the in-
ternal piping in the boiler has already been substracted.
When determining proper piping of the heating system, verify that the internal boiler circulator
will overcome the head loss of the system at the designed
fl
ow rate using the graph above.
If the internal circulator is
adequate
, direct system piping can be utilized. See section 4 page
11 for suggested direct supply/return piping.
If the internal circulator is
inadequate
, a secondary circulator must be utilized. See sections 14
for suggested primary/secondary piping.
13.2 Expansion vessel:
The height difference between the C.h. PRV (19 on page 10) and the highest point in the
system may be 23 ft at most. For greater differences, increase the pre-load pressure in the
C.h. expansion vessel (17 on page 10) and the system when cold, by 0.1 bar for additional
3.3 ft. For systems with volumes greater than 154l, an additional expansion vessel must be
provided.
