Pipes, Expansion Vessel And Safety Valves; Recirculation Pump (Fig. 7); Adjusting The Door (Fig. 8); Assembly Of The Burner (Fig. 9) - Ferroli PREXTHERM RSW Serie Instrucciones Para El Uso, La Instalación Y El Montaje

5.5.4 Pipes, expansion vessel and safety valves

PREXTHERM RSW N boilers are suitable for operation with forced water circulation, with the expansion vessel open or closed. An expansion
vessel is always required to compensate for the increase in water volume due to heating. In the first case, the height of the hydrostatic column
must be at least 3 meters above the boiler body. Its capacity must be sufficient to contain the increase in volume of all water in the system,
between the surface of the water in the vessel and the overflow pipe. Tall, narrow vessels are preferable, as they ensure minimum contact
between the water surface and the air, thus reducing evaporation. In the second case, the capacity of the closed expansion vessel must be
calculated considering:
- the total volume of water contained in the system
- the maximum operating pressure of the system
- the maximum operating pressure of the expansion vessel
- the initial pre-charge pressure of the expansion vessel
- the boiler's maximum operating temperature (the maximum temperature on the thermostat fitted on the panel is 90ºC; use 100ºC to perform
this calculation).
The expansion pipe connects the expansion vessel to the system. This pipe will start at the T3 fitting (see the Dimensions table), and must not
be fitted with on-off valves. At fitting T3, or within 0.5 m of the first flange on the outlet pipe, install a safety valve suitable for the capacity of the
boiler and in compliance with current local standards. No type of shut-off device may be installed between the boiler and the safety valves, and
these valves should be set to operate when the maximum permitted operating pressure is exceeded.

5.5.5 Recirculation pump (Fig. 7)

Condensation of the water vapor contained in the flue gas leaving the boiler (condensate) occurs when the return water temperature is below
50ºC. This is significant, particularly when the boiler is turned on in the morning after being off all night. Condensate is acidic and corrosive, and
will damage the metal plating on the boiler over time. It is therefore advisable to install a recirculation pump with an anti-condensation feature,
to be fitted between the feed and return fittings, upstream of any mixing valve. While the system is operating, the pump must ensure a flow-rate
of 20 to 30% of the total. The (anti-condensation) recirculation pump is controlled using the Low-Temperature Thermostat Panel (optional). The
bulb for the corresponding thermostat must be fitted at the return (using a sheath that must be added by the installer of that pipe).

5.6 Adjusting the door (Fig. 8)

PREXTHERM RSW 92÷600 N (Fig. 8)
Opening
The burner door can be opened to the right or left. Simply loosen nuts 1 on the right or left.
Horizontal tightness and adjustment
Rotate both lock nuts 2, tighten nuts 1 as needed, and lock both lock nuts 2.
Vertical positioning and adjustment
After assembling the burner, it may be necessary to reposition the door. To do so, loosen nuts 1, loosen set screws 3, and adjust with nuts 4.
Tighten nuts 1 to completely flatten seal 5.
After installing the burner, the door must be positioned. This can be done by loosening nuts 1 and 3 and set screw 5, and using nut 6 to adjust the
height. This must be done so that the entire rope seal presses against the plate, by tightening nuts 1 and 3.

5.7 Assembly of the burner (Fig. 9)

The assembly of the burner at the boiler door must ensure perfect tightness for the products of combustion. Once the burner is installed on the
boiler, the space between the burner nozzle and the refractory material on the door must be filled with the ceramic fiber padding (A) provided.
This prevents the door from overheating, which would result in irreversible warping. The fuel connections to the burner must be placed so that
the boiler door can open completely with the burner installed.
It is advisable to place a rigid supporting base under the burner to prevent its full weight from negatively affecting the door.
RSW
92-152 N
190-401 N
525-600 N
EN
48
L min. (mm) L max. (mm)
230
250
250
cod. 3541P130 - Rev. 00 - 02/2018
PREXTHERM RSW 92N ÷ 600N
300
320
360