Unical DUA plus Installation And User Instruction Manual Download Page 19

Page: 19 / 32

Installation info

fig. 19

fig. 20

By-Pass
OPEN
turn the screw
by anticlockwise
rotation

By-Pass
CLOSED
turn the screw
by clockwise
rotation

2.2.11 -

HYDRAULIC CONNECTIONS

Before installing the boiler we recommend
that the system be cleaned to remove any
impurities which could originate from
components and which could risk damaging
the circulating pump and heat exchanger.

HEATING

The heating flow and return must be
connected to the relevant ¾” connections
of the boiler

and

(see fig. 7).

When determining the size of the heating
circuit pipes it is essential to bear in mind
the pressure losses induced by radiators,
any thermostatic valves, radiator cut-off
valves and the configuration of the system.
In the boiler, between the flow and return
pipes,an automatic bypass device is fitted
(a differential valve with a flow rate of
about 150 l/h) which guarantees always
minimum flow rate through the heat
exchanger, also in the case, for instance,
that all the thermostatic valves fitted on the
radiators, are closed.

It is possible to adjust the by-pass by acting
onto the adjusting screw (see fig. 20).

We recommend that the discharge of the
safety valve mounted in the boiler be
conveyed into the sewer.
If this precaution is not taken, activation of
the safety valve may result in flooding of
the room where the boiler is installed.
UNICAL shall not be held responsible for
damage caused by non-observance of this
technical precaution.

D.H.W. (Domestic Hot Water)

Inlet and Outlet and of D.H.W. must be
connected to the relevant ½” connections
of the boiler

and

(see fig. 7).

For the lower connections positioning,
see the mounting jig of figure 9

The pressure in the water mains must be
between 1 and 3 bar (in case of higher
pressure it is necessary to fit a PRV
(Pressure Reducing Valve).

The hardness of the supply water affects
the frequency of the cleaning of the heat
exchanger; the opportunity to install a
water softning device depends on the
characteristics of the water it self.

NOTE:
With a water whose hardness is higher
than 20°f the use of a softner is strongly
recommended

2.2.12 - ELECTICAL CONNECTIONS

The electrical connections of

DUA plus 30

tank

are shown in the clause ‘’WIRING

DIAGRAMS’’ (par. 2.3 - pag. 17).
The boiler must be connected to
the mains supply at

230 V - 50 Hz

. This

connection is to be perfectly done, as
foreseen by the IEC and local rules and
must be earthed.

This fundamental requirement for safety
purposes must be checked; in case of
doubt, ask for a professionally qualified
technician to check the electrical system.

UNICAL

disclaims all liability for damage or

caused by failure to earth the system.

Gas, domestic water and central
heating pipes are not suitable for
earthing purposes.

The boiler is supplied with 1.5 m long
3x0,75mm² cord. Phase

Phase

Phase and Neutral

Neutral

Neutral must

compulsory be connected to Phase

Phase

Phase and

Neutral

Neutral of the supply socket.
A double pole switch with a distance
between the contacts higher than 3 mm,
must be installed upstream the boiler to
enable all maintenance operations to be
carried out safely.

DIAGRAM FLOW RATE/MANOMETRIC HEAD AVAILABLE FOR C.H. SYSTEM

= By-Pass CLOSED
= By-Pass OPEN

..............

Flow rate l/h (Q)

Available Manometric Head m c.e.

2.2.10 - GAS SUPPLY LINE

The gas supply line must have a diameter
equal or larger than the one used in the boiler.

Comply with the applicable local installation
requirements which shall be considered as
having been incorporated in full in this
manual.
Before opening the internal gas supply
system; i.e. before connecting the gas
meter, all seals must be checked.

If any part of the system is concealed the
seals must be checked before the pipes
are covered.
The seal test must be conducted using air
or nitrogen at a pressure of at least 100
mbar.
The commissioning of the boiler also
includes the following operations and
checks:
- Opening of the gas gate valve and venting
of the air contained in the piping and boiler,
proceding appliance by appliance.

- Check, with the gate valve of all the
appliance
Off, that there are no gas leaks.
During the 2

quarter of a hour from the

beginning of the test no pressure reduction
is to be detected on the gas pressure
gauge. If gas leaks have to be found, use
only water soap solution or any other
specific gas leak detector which can be
available on the market. Never look for gas
leaks using a nacked flame.