5.3
DESIGN FEATURES
5.3.1
OUTER BODY
The outer body containing the primary fluid is made of STW 22 steel.
5.3.2
TANK-IN-TANK TYPE EXCHANGER ACCUMULATOR
The ring-shaped inner tank with its large heating surface for producing
domestic hot water is built of Chrome/Nickel 18/10 stainless steel. It is
corrugated over its full height by an exclusive production process and
entirely by argon arc welded by the TIG (Tungsten Inert Gas) method.
5.3.3
COMBUSTION GAS CIRCUIT
The combustion gas circuit is protected by cold galvanisation. The
combustion gas circuit comprises:
5.3.3.1
Flue pipes
Depending on output, ALFA Gas models contain 4 or 8 steel flue
pipes with an internal diameter of 64 mm. Each pipe is fitted with
a baffle of special steel designed to improve heat exchange and
reduce flue gas temperature.
5.3.3.2
Combustion chamber
The combustion chamber on ALFA Gas models is water cooled.
5.3.4
INSULATION
The boiler body is fully insulated by rigid polyurethane foam with a high
thermal insulation coefficient, sprayed on without the use of CFCs.
5.3.5
JACKET
The boiler is covered by a steel jacket which has been scoured and
phosphated before being stove enamelled at 220° C.
5.3.6
BURNER
ALFA Gas boilers are fitted with an atmospheric burner with electric
ignition.
5.3.7
CONTROL PANEL
(Fig. 14)
1 - Thermostat adjustable between 60 and 90° C
2 - On/off switch
3 - Summer/winter selector
4 - Thermometer
Fig. 14: Control panel
1
2
3
4
5.1
OVERVIEW
•
Dual application boiler (central heating and domestic hot water).
•
Designed for connection to a chimney or suitable flue.
•
TANK-IN-TANK indirect storage type domestic hot water production.
•
Fittings for connecting the circulation kit to feed the heating circuit
(available as an option)
.
•
Control panel with setting thermostat (60/90 °C), on/off switch,
Summer/Winter selector, thermometer, warning lamp and burner
reset button.
•
Flue gas anti-backdraught safety device.
•
Delivered complete with atmospheric type burner.
•
ALFA G for natural gas, with rated output of 20.3 kW.
•
ALFA GP for propane, with rated output of 23.5 kW.
5
DESCRIPTION
Fig. 13: Ballon inox sanitaire
8
5.2
DESCRIPTION OF OPERATION
5.2.1
THE TANK-IN-TANK CONCEPT
The ALFA Gas series differs from traditional hot water producers
because of its ring-shaped tank immersed in the primary fluid contained
in the outer body. When there is a demand for hot water from the central
heating system or the domestic hot water system, the thermostat starts
the burner. The combustion gases quickly heat up the primary fluid,
creating a natural circulation around the tank.
5.2.2
DOMESTIC HOT WATER HEATED INDIRECTLY
This circulation facilitates heat exchange between the primary fluid and
the domestic water, which takes place all over the tank surface. The
corrugations on the inner and outer shells of the ring-shaped tank
further boost the area of heat exchange and speed up the heating
process of the domestic water.
5.2.3
EASY SETTING AND SAFETY ASSURED
With a single command, the water temperature of both the primary circuit
and the hot water circuit is set by the adjustable thermostat situated on
the tank in the primary circuit. A manually reset safety thermostat shuts
off the burner if the temperature reaches 103° C.
