Honeywell NA 228 S-A Product specification sheet

for closed heating or cooling systems

4

6

GRÄSSLIN

2

bar

8

0

h

220V~50Hz

Z 52

UW

vom Kaltwassernetz

Nachfüllautomat Typ: NA 228

Construction

The automatic refilling unit comprises:

● Powder coated pressed steel housing

● Drinking water and system connection with shutoff ball valve

● Pressure switch for cut-in and cut-out pressures

● Electronic time relay

● Fault indicator lamp and cut-out button

● Pressure gauges for inlet and system pressures

● Discharge tundish

● Electrical plug for remote connection

● ON/OFF switch

● One metre connection cable without plug

● Water meter

● Bush for cable connection to a building management

system

● Operating-time meter

* For temperatures above 100ºC, the pressure at the highest point in the system when the

system is cold must be at least 1.0 bar above the operating pressure (static height plus 1.0 bar).

**A pressure reducing valve must be fitted before the refilling unit for pressures above 6.0 bar

10

5

SPX

1996

TÜV / DVGW
230V ~

50/60 Hz

15

bar

16

0

30 Watt

NA 228 S-A

A utomatic Refilling Unit

Product specification sheet

Application

The NA 228 S-A automatic refilling unit with DVGW-tested
backflow preventer permits the fixed connection of closed heating
or cooling systems to the drinking water supply network.

It integrates a backflow preventer, a check valve and a water
meter in a single unit. The automatic refilling unit maintains
pressure between prescribed upper and lower limits in closed
heating and cooling systems. It prevents back flow, back
syphonage or back pressure of the heating or cooling water
into the potable water network. Limitation of the refilling time is
also provided as well as the facility for fast and automatic
refilling of the system. In addition, build up of steam in the
system caused by loss of pressure is prevented.

Special Features

● Components DVGW approved

● Electrical changeover valve for control of the backflow preventer

● Supplementary hot-water-resistant check valve for

increased protection of the drinking water network

● Setting facility for fast filling or refilling of the system

● Pressure switch with separately adjustable cut-in and

cut-out pressures

● Time relay, for limitation of the refilling period

● Standardised discharge connection

● Remote volt-free connection

● Bush for cable connection to a building management system

● Circuit protection for volt-free connection

● Operating-time meter, measures the refilling time

● Water meter, measures the refills

Range of Application

The following operating data applies for the downstream system:
System pressure: Maximum 6.0 bar
Temperature: Maximum 120 ºC

Technical Data

Refilling: Flow rate 110 litres/h at ∆p = 2.0 bar
Fast filling: Flow rate finely adjustable between

110 litres/h and 1100 litres/h at ∆p = 2.0 bar
Duration of fill: Adjustable between 5 and 100 minutes
Cut-in pressure: Adjustable between 0.2 and 7.5 bar
Cut-out pressure: Adjustable between 0.5 and 8.0 bar
Pressure switching
differential: 0.3 to 0.5 bar (depending on pressure range)
Water inlet pressure: Minimum 3.0 bar, maximum 6.0 bar**
Remote connection: Volt-free contact
Supply voltage: 230V, 50/60 Hz
Power consumption: 30W
Connection size: R

1

/2" and Ø15

Subject to change 03/99

221

Automatic Refilling unit NA 228-SA

T

NETZ

EIN/AUS

zur Heizungsanlage

Fremdanschluß

- potentialfrei -

B

00 00 000 0

5

bar

0

Method of Operation

If the system pressure falls to below the lower set value, for
example through leakage losses, then the changeover valve is
opened by electrical impulse via the pressure switch and thereby
permits supply to the backflow preventer . The inlet pressure moves
the backflow preventer to the flow position and the system is
refilled until the pressure rises to the upper set limit. The time
period of the refill is monitored by the time relay and the operating
time counter. Once the upper limit value has been reached, the
pressure switch closes the changeover valve and the backflow

H

10

15

16

preventer goes to the shutoff position (open to atmosphere). The
time relay then returns to the initial position.
If the inlet pressure falls to the operating pressure of the
backflow preventer (2 bar) during the automatic refilling
operation, then 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)

Option

NA 228 S-A

Connection size R

1

/2"
Soldered connection size (mm) Ø15
Weight (approx. kg) 16
Dimensions (mm)

H 380
B 370
T 160

Test Certificate Number 101/87/147

222

Braukmann Water Control . Honeywell AG

Subject to change 03/99