Single-Pipe Systems; The Loop Circuit; Hydraulic Connections - Riello RL 42 BLU Installation, Use And Maintenance Instructions

5.8.4

Single-pipe systems

There are two solutions possible:
➤ Pump external by-pass (A, Fig. 16) (recommended)
Connect the two flexible hoses to an automatic degassing
unit.
In this case screw 7)(Fig. 25) must not be removed: pump in-
ternal by-pass closed.
➤ Pump internal by-pass (B, Fig. 16)
Connect only the flexible suction hose to the pump.
Remove screw 7)(Fig. 25), which can be accessed from the
return union: pump internal by-pass open.
Plug the pump return line connection.
This solution is possible only with low pump depression val-
ues (max. 0.2 bar) and perfectly-sealed piping.
5.8.5

The loop circuit

A loop circuit consists of a loop of piping departing from and re-
turning to the tank with an auxiliary pump that circulates the fuel
under pressure.
A branch connection from the loop goes to feed the burner.
This circuit is extremely useful whenever the burner pump does
not succeed in self-priming because the tank distance and/or
height difference are higher than the values listed in the Tab. G.
5.8.6

Hydraulic connections

The pumps are equipped with a by-pass that connects return line
with suction line.
The pumps are installed on the burner with the by-pass closed by
screw 7)(Fig. 25). It is therefore necessary to connect both hoses
to the pump.
The pump will break down immediately if it is run with the return
line closed and the by-pass screw inserted.
Remove the plugs from the suction and return connections of the
pump.
Insert the hose connections with the supplied seals into the con-
nections and screw them down.
Take care that the hoses are not stretched or twisted during in-
stallation.
Route the hoses through the holes in the plate, preferably using
those on the rh side:
➤ unscrew the screws 1)(Fig. 17), now divide the insert piece
into its two parts 2) and 3) and remove the thin diaphragm
blocking the two passages 4).
➤ Install the hoses where they cannot be stepped on or come
into contact with hot surfaces of the boiler.
➤ Now connect the other end of the hoses to the supplied nip-
ples, using two wrenches, one to hold the nipple steady
while using the other one to turn the rotary union on the
hose.
20023224
Installation
D828
16 GB
A B
Fig. 16
Fig. 17