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SIT Group

INTEGRATED SYSTEM

PERFORMING THE GAS/AIR

FLOW CONTROL AND MIXING

Application

Fan assisted gas firedappliances with premixburner. 390 MIXER isparticularly suitable formodulating condensingboilers.

SIT 390 MIXER

9.955.048

048

Subjecttochangewithoutnotice

Main features

Two heat-input models.Wide modulation range.

w w w . s i t g r o u p . i t

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CONSTRUCTION CHARACTERISTICS

Die casting aluminium body

Air signal to the gas/air control connection

MECHANICAL CONNECTIONS

Mounting Position Downstream of the fan

Gas families 2nd and 3rd

Ambient temperature No inconvenience in operation within standard

working condition of gas appliances (-20....+100 C)

USE SPECIFICATION

Air inlet and mixture outlet M5 (4) Flanges

Gas inlet G 3/4 ISO 228

or: Rp 1/2 ISO 7

or: M4 (4) Flanges

Air signal 6.5 mm

GENERAL DATA

2

1 Gas/Airmixture outlet.

2 Air Inlet.

3 Gas Inlet.

4 Air signal connection.

DESCRIPTION

1

2

3 4

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3

Maximum heat input available with reference to the pressure drop between the outlet and theinlet of the 390 MIXER in operating condition.Reference conditions: gas G20.

MAXIMUM HEAT INPUT

MINIMUM HEAT INPUT

5 kW

7 kW

Minimum HeatModel MIXER

390. 0xx

390. 1xx

Model MIXER

35 kW

25 kW

# 2

# 1

Reference HeatInput

390. 0xx

390. 1xx

The minimum available heat input is strictly related to the appliance characteristics.As a general guideline the minimum heat input is 20% of the maximum(modulation range 1:5).In the following table the nominal value of the minimum heat input, when theminimum pressure drop between the inlet of 390 MIXER and gas injection section is50 Pa, is reported.Reference conditions: gas G20, gross calorific value.

CAPACITY

0 50 100 150 200 250 300 350 400 450 500 550 600

0

9

18

27

36

45

54

650 700

10

20

30

40

50

60

0

Maximum Heat Input (indicative)

Heat Inputbased on gross CV

Heat Inputbased on nett CV

p [Pa]

# 2

# 1

kW kW

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4

OPERATION

Stand by - With the appliance in not-operating condition there is no air flow and the gas

way is closed by the gas/air control valves.

Pre-purge - When the appliance is in pre-purge condition there is air flow throughMIXER.

848 SIGMA

390 MIXER

gas

848 SIGMA

air

gas

390 MIXER

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5

The inner profiles of MIXER are designed and realised in order to ensure the mixingfunctions and to increase the modulating range.

INNER VIEW

390 MIXER

Venturi Pipe

Air signal

compensation chamber

Gas inlet chamber

Gas/Air mixing

chamber

Operating - Automatic shut off valves open. The gas flows through the control andit is injected inside the MIXER in the mixing chamber. Then the gas/air mixture leavesthe MIXER and goes to the burner.

848 SIGMA

gas

air

390 MIXER

OPERATION

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LAY-OUT ASSEMBLING

GAS

AIR

MIXTURE

BURNER

FAN

390 MIXER

AIR SIGNAL

848 SIGMA

6

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DIMENSIONS

7

70

70

96

47

60

50

54

6.5

50

60

G3/4

ISO2

28

32

24

24

32

GasConnectio

n:Flangesversion

GasConnection:G

3/4version

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SIT GROUPwww.sitgroup.it - e-mail: mkt@sitgroup.it