QHT Riva Installation, Operation And Service Instructions - page 32
RIVA HEAT ONLY MANUAL - REV B
32
13.1 Circulator capacity as a function of flow rate:
Figura 13.1
The hydraulic specifications in Fig 13.1 represent the pressure (available head for
the central heating system) as a function of the flow rate. The pressure loss due to
the internal 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 flow rate using the
graph above.
If the internal circulator is adequate, direct system piping can be utilized. See section 4
page 12 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 11) 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 11) 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.
13. Circulator Sizing