Honeywell NA 225-A Product specification sheet

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R 295 SA

EA 2

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10

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15

bar

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16

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1

Nachfüllstation
Typ: NA225-A

CE

230V
50 / 60 HZ
20W IP65

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1

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Construction

The refilling unit consists of:

● Threaded drinking water and system connections

● Changeover valve

● R 295 SA -

1

/2" backflow preventer

● Cut-in/cut-out pressure switch

● Electrical connector strip

● Time relay

● Discharge tundish

● Inlet pressure gauge

● Drain valve

● Cable wiring centre

● One meter electrical connection cable

NA 225-A

Automatic refilling unit

for heating and cooling systems

Product specification sheet

Purpose

The NA 225 - A refilling unit with DVGW tested backflow
preventer enables permanent connection of closed heating and
cooling systems to the drinking water network.

It combines a backflow preventer and non-return valve in one
appliance. The refilling unit maintains system pressure between
pre-determined upper and lower limits in closed heating and
cooling circuits. It prevents backflow, back syphonage or back
pressures of heating or cooling water into the drinking water
network and enables limitation of the refilling period. In addition,
it prevents generation of steam in a system caused by pressure
loss.

Special Features

● DVGW approved

● Pressure switch

● Drain valve for when cut-in and cut-out pressures are

to be changed

● Electronic time relay for limitation of the filling period

● Inlet pressure gauge

● Standardised discharge connection

Range of Application

The following operating conditions apply for the
downstream system:
System pressure Maximum 4.0 bar
Water temperature
at the refilling unit Maximum 40°C

Technical Data

Refilling Flow rate 110 litres/h at ∆p = 2 bar
Cut-in pressure 2.5 bar (set during manufacture)
Cut-out pressure 2,8 bar
Switching pressure
differential 0,3 bar
Inlet water pressure Minimum 3.0 bar, maximum 4.0 bar**
Electrical supply 230 V~ 50/60 Hz
Electrical loadv 30 W

** A pressure reducing valve must be fitted for inlet pr essur es above 4.0 bar

Subject to change 03/99

233

Automatic refilling unit NA 225-A

H

Nachfüllstation
Typ: FA225

CE

230V •
50 / 60 HZ
20W IP65

Method of Operation

If the system pressure falls below the set limit, for example
because of leakage losses, then the changeover valve is
opened by an electrical impulse from the pressure switch and
thereby opens the hydraulic supply to the backflow preventer.
The inlet pressure brings the backflow preventer to the flow
position and the system is refilled up to the pre-set upper
pressure limit. The duration of fill is controlled by the time relay.
Once the upper fill pressure has been reached, the pressure
switch cuts out, the changeover valve closes and the backflow
preventer goes to the cutoff position. The time relay goes to the
outlet position.
If the inlet pressure during the filling operation falls to the
backflow preventer set pressure (2 bar), the backflow preventer
automatically goes to the shutoff position (open to atmosphere).
The shutoff position of the backflow preventer is indicated in
the viewing window (green visible = shutoff position).

B

Weight Approx. kg 2,9
Dimensions (mm)

H 285
B 188

T65

Test No. for R 295 SA
backflow preventer DIN/DVGW 569 E

Versions

A = Normalausführung

Ordering Number

NA 225 - A

234

Braukmann Water Control . Honeywell AG

Subject to change 03/99