Honeywell NA 225-A Product specification sheet

R 295 SA

EA 2

bar

Nachfüllstation Typ: NA225-A

230V 50 / 60 HZ 20W IP65

Construction

The refilling unit consists of:

● Threaded drinking water and system connections

● Changeover valve

● R 295 SA -

/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

Nachfüllstation Typ: FA225

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).

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

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