Caleffi 553 User Manual

Pre-adjustable filling units

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BSI EN ISO 9001:2000

Cert. n° FM 21654

UNI EN ISO 9001:2000

Cert. n° 0003

USC

& backflow preventer

series 553 - 573

CALEFFI

01061/08 NA

Replaces 01061/04 NA

Function

The automatic filling unit is a device consisting of a pressure
reducing valve with compensating seat, an inlet filter, a shut-off
valve and a check valve.
It is installed on the water inlet piping in sealed heating systems,
and its main function is to maintain the pressure of the system
stable at a set value, automatically filling up with water as required.

This product has the characteristic of being pre-adjustable,
which means that it can be adjusted at the required pressure
value before the system charging phase.

After installation, during the filling or topping-off phase, the water
feed will stop when the set pressure is reached.
A pre-assembled version is also available, complete with upstream
backflow preventer.

Product range

Code 553542A Filling unit with pressure gauge and pressure setting indicator Size 1/2”
Series 573 Backflow preventer with intermediate atmospheric vent with threaded connections Size 1/2” - 3/4”
Series 573 Backflow preventer with intermediate atmospheric vent with sweat connections Size 1/2”
Code 573002A Charging unit complete with backflow preventer 573 series with threaded connections Size 1/2”
Code 573009A Charging unit complete with backflow preventer 573 series with sweat connections Size 1/2”

Technical specification

Filling unit

Material: Body: brass

Cover: PA 66 GF 30
Seals: NBR

Maximum Working Pressure: 230 psi (16 bar)
Pressure setting range: 3÷60 psi (0.2÷4 bar)
Factory setting: 15 psi (1.035 bar)
Indicator accuracy: ±2 psi (±0.15 bar)
Maximum Working Temperature: 150°F (65°C)

Connection: Inlet: 1/2” NPT Male

with union tailpiece

Outlet: 1/2” NPT Female

Backflow preventer

Material: Body: brass

Filter: stainless steel
Check valve: PSU
Check valve stem: brass
Diaphragm: EPDM
Seals: EPDM

Maximum working pressure: 175 psi (12 bar)
Maximum working temperature: 210°F (99°C)
Medium: water

Certified to: CSA B64.3 and ASSE 1012

Connections: 1/2”-3/4” NPT female with union

1/2” sweat with union

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0

10

20

30

40

50

CALEFFI

bar
psi

Dimensions

E

DC

A

Code

553542A

A

1/2"

4

B

13/16

PREVE

/4”

W

-3

O

73
5

1/2”

N

BACKFL

Series:

Sizes:

A’

1/2”
3/4”

1/2”

SWT

NPT

VENT

C

B

S/

1/2”
1/2”
1/2”
1/2”

A’

PREV

/4”

W

-3

O

73
5

1/2”

N

BACKFL

Series:

Sizes:

1/2"

1/2”

S/

VENT

B

C

A

A’

1/2"

SWT

1/2”

NPT

B

1/2”
1/2”

C

9

3/16

“

1/8

“

9

A

D E

D

C

B

1

4

3/4

“

3/8

“

5/8

“

3/8

“

Code

“

573002A

“

573009A

4

4
4

11/16

5/8

1
1

“

3/8

“

3/8

1

A’

D

E

1

3/8

“

4”

1

3/8

“

4”

A

D

A

Code

B

573403A
573503A
573409A

“C1

15/16

“D4”

573493A

1/2”

3/4”
1/2”
1/2”

A

SWT

1/2”

SWT

Construction details

Pre-calibration

This model is equipped with a
pressure setting indicator for
the commissioning operation.
The system charge pressure
can be input by
means of the
adjusting screw,
before the start
of the system
charging phase.

Anti-stick materials

The central housing containing
the moving parts and the internal
compensating spindle are made
of a low adhesion coefficient
plastic. This material minimises
the risk of for

mation of scale
deposits, the main cause of
malfunctions.

Diaphragm-seat seal

Spindle guide

In order to reduce the frictional
surfaces, the spindle unit guide has
been positioned in the upper part of
the device.
It consists of four
spokes formed
directly on the
plastic central
support.

Removable filter cartridge

The cartridge containing the operating mechanisms, protected by
a large surface area strainer, is removable. This makes it very easy
and quick to carry out inspections, internal cleaning and even
replacement of the cartridge itself.

The useful working surface of the diaphragm is particularly
large, in order to guarantee greater precision and sensitivity
when working with minimum pressure differences.
This feature is also
useful in that it
gives greater power
to the sliding of
the spindle and
overcomes friction.
In view of the low flow rates involved, the filling unit seat has been
designed with the smallest possible diameter.

➩

This factor, combined with
the extended surface of
the diaphragm, creates an
optimum dimensional ratio
for a piece of equipment
which must maintain its
operating characteristics
unchanged over time.