Sentinel SCU User manual

INSTRUCTION MANUAL
Sentinel Corrosion Monitor SCU
04/2019
SCM SCU Instructions V1 0419

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■ TABLE OF CONTENTS
1 LIST WITH ABBREVIATIONS 3
2 SYMBOLS 3
3 GENERAL DESCRIPTION 4
4 CONTENTS IN THE PACKAGE 5
5 APPLICATIONS 6
6 INSTALLATION 7
7 ACTIVATION 11
8 OPERATION / USE 13
9 READING 14
10 REPLACEMENT 15
11 DISMANTLING 15
12 REMARK 16
13 TECHNICAL DATA 16
13.1 FUNCTIONAL 16
13.2 MAINS ADAPTER 16
13.3 SENSOR 17
13.4 DIMENSIONS / WEIGHT 17
14 ACCESSORIES 18
14.1 USB CABLE 18
14.2 RETRACTOR 18
15 DECLARATION OF CONFORMITY 19

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■ 1 LIST WITH ABBREVIATIONS
HVAC Heating, Ventilation, Air-conditioning and Cooling
USB Universal Serial Bus
LED Light Emitting Diode
PC Personal Computer
VAC Volts Alternating Current
VDC Volts Direct Current
(m)A (Milli)amperes
mm Millimetre
CE European Conformity
(in accordance with the European legislation)
EMC Electromagnetic Compatibility
RoHS Restriction of Hazardous Substances
Rc Radius of Curvature
Hz Hertz
W Watt
RH Relative Humidity
■ 2 SYMBOLS
Warning about bodily harm/injury
CAUTION! Warning about poor operation and/or damage to
equipment
NOTE Tips for easier use

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■ 3 GENERAL DESCRIPTION
Sentinel Corrosion Monitor SCU is a patented measuring instrument that
monitors the durability of your heating system in a reliable manner by
providing timely warning of internal corrosion (or the formation of rust),
and also of the particularly harmful eects that may be caused by such
corrosion.
The corrosion monitor therefore can help to prevent unwanted problems,
such as the break-down of boilers and pumps, seized valves, leaks and
blockages caused by poor water quality. Use of the monitor may lead to
prolonged service life for your heating system, higher living comfort, less
unwanted costs and signicant savings of energy and materials.
The sensor consists of two components: a probe and a data logger. By
means of the threaded connection, the probe is mounted perpendicular to
the pipe, with the tip in the water ow. The oxidation of a small piece of metal
in the probe is representative of the general corrosion within the system.
The sensor records the rate of corrosion and warns if the rate becomes
unacceptable or the sensor requires attention.

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■ 4 CONTENTS IN THE PACKAGE
• Probe with protective cap
• Threaded connection
• Data logger + Quick Guide
• Mains adapter
• 2x Tie wraps (colson strips)
• Instruction Manual
• Assembly guide

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■ 5 APPLICATIONS
Sentinel Corrosion Monitor SCU is a corrosion sensor for water-based
thermal systems. Studies on corrosion processes in heating systems reveal
that corrosion is a complex phenomenon that is aected by many factors.
The presence of oxygen in the system water is the main cause of general
corrosion in a system. The corrosion monitor is based on an innovative and
patented technology that measures this general corrosion directly.
The major sources of oxygen in the system water are the following:
(see also the European standard EN14868)
• oxygen in the lling water (~10 mg/l) during the initial lling;
• oxygen ingress due to negative pressure zones in the system, caused by
inadequate pressure maintenance (expansion system);
• oxygen ingress due to diusion through materials that are not oxygen-
tight (synthetic pipes, rubber hoses, membranes of expansion tanks,
etc.);
• oxygen in the extra lling water through topping up
(~10 mg/l);
• oxygen in the trapped air due to insucient venting of the system during
initial lling;
• constant equilibration with atmospheric oxygen in open systems.
It is important that chemical treatment in systems is regularly checked
and properly maintained to ensure adequate system protection from scale
and corrosion. In larger systems or those treated with chemical inhibitors,
additional monitors at dierent locations on the system can improve
measurement accuracy.

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■ 6 INSTALLATION
PREPARATION
1. The sensor is should be installed in the return section of the system, at a
location with adequate ow. The tip of the probe must be placed entirely
in the ow. The installation location must be free of pressure during the
initial installation.
2. Select a location with sucient space around it in order to be able to use
the Retractor to replace the probe under pressure when necessary.
(Fig. 1)
3. Avoid placing the sensor in direct sunlight. (Fig. 2)
(Fig. 2)
(Fig. 1)

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4. The sensor can be installed by one of three procedures:
In all cases a female G1/2 or Rc1/2 thread is required
a. in an existing socket with a length of max. 25 mm
b. in a T-piece (Fig. 3)
c. in a welding sleeve with a length of max. 25 mm
(probe tip must be well within the ow).
CAUTION! Fittings with a reduced bore or collar could narrow the
threaded connection due to radial compression, and this in turn could
block the probe tip in the t, which has now become too narrow, and
cause irreparable damage.
INSTALLATION
To provide protection against corrosion and limescale, cleaning and
ushing of the system followed by chemical addition of inhibitor should be
considered. Major boiler manufacturers recommend that once cleaned,
commercial heating and closed cooling systems should be dosed with
Sentinel X100 Inhibitor. Prior to adding X100, the system should be cleaned
with either X400 High Performance Cleaner or X800 Fast Acting Cleaner.
More information on these products can be found at:
https://www.sentinelprotects.com/uk/products/commercial/central-
heating-systems
1. Screw the threaded connection tight. Use a suitable sealant. (Fig. 3)
CAUTION! Hand-tighten this threaded connection loosely and
then tighten another quarter turn using a wrench. The connection
should not be forced. If tightened with too much force, the threaded
connection could be narrowed due to radial compression, and this,
in turn, could block the probe tip in the t that has now become too
narrow, and cause irreparable damage.
(Fig. 3)

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2. Remove the protective cap from the probe. (Fig. 4)
CAUTION! The probe tip should not be damaged.
3. Measure the mounting depth as shown in Fig. 5. Mark this distance on
the probe.
CAUTION! The probe tip must be well within the ow.
4. Screw the probe into the threaded connection to the correct depth, as
marked.
(Fig. 4)
+/- 5mm
(Fig. 5)

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CAUTION! Do not use sealant (ax, Loctite, etc.). The double
O-rings of the probe are an eective seal. (Fig. 6) The screw thread
serves to ensure that the correct mounting depth for the sensor is
reached. The screw thread must never be damaged. Do not scratch!
5. Click the data logger rmly onto the probe (only one position is possible).
(Fig. 7) Position the data logger as shown in Fig. 8 to protect the connectors
and control button from spray water.
CAUTION! Verify that the data logger has been pushed far enough over
the probe (O-ring of the probe should be fully inside the collar of the
logger). However, never use the logger to screw the probe in or out.
CAUTION! The USB connector between data logger and probe cannot
be used to read data.
(Fig. 8)
(Fig. 6)
(Fig. 7)

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■ 7 ACTIVATION
CAUTION! The activation of the monitor takes place as follows:
- in a new system: before the ushing/initial lling with water;
- in an existing system: during assembly.
1. Plug the mains adapter in the nearest socket and connect the data
logger to the power supply. (Fig. 9)
NOTE: If not available, or if the power cable is too short, an extension
cord can be used to connect the mains adapter to a remote socket, or
to the power supply panel of the boiler. Do not use a USB extension
cable.
When connecting the data logger to the power supply, the LEDs will blink
alternately red and green several times.
(Fig. 9)

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2. Secure the cable with the provided strain relief (labyrinth or tie wrap),
and lay the cable in a loop to prevent dripping or splashing water from
reaching the connector along the cable. (Fig. 10)
From now on, the sensor LED will blink green every 2 seconds. The
corrosion LED lights green and will blink o every 8 seconds.
From now on, the monitor will run a measurement every 20 minutes and
log it every 7 hours.
Four days are sucient to calculate an indicative value for the yearly
corrosion rate, seven to generate an alarm if the corrosion rate is
unacceptable.
(See also 9. Reading.)
3. Enter the date of installation on page 18 of this manual.
4. The integrated alarm relay can be connected to an external safety circuit
through the green terminal connector (e.g. a building management
system, an external alarm system or the safety circuit of the heat
generator). The circuit is closed in case of normal operation of the
corrosion monitor and interrupted in case of an alarm, or when there is
no power.
CAUTION! The relay with normally open contact is closed during the
operation of the sensor. In the event of alarm, the relay interrupts the
external safety circuit of max. 48 VAC/VDC. 2 A / 60 W. The relay is
NOT suitable for 230 volt.
NOTE: If the safety circuit of the heat generator is connected and
the heating system stops operating the mains power supply of the
monitor fails (e.g. faulty cable, supply, fuse, etc.), . In this case, also the
‘ALARM IGNORE’ key does not work. This can be temporarily remedied
by a bridge in the terminal connector. This causes only the relay to be
seemingly closed, so that the boiler can operate again. However, the
sensor still does not operate.
(Fig. 10)

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Setting the limit value for the annual corrosion rate. The limit value is pre-set
to 24 μm per year. This value can be adjusted by means of the dashboard
software (see Chapter 9).
■ 8 OPERATION / USE
1. LED’S:
CORROSION
STATUS
SENSOR
STATUS PROBLEM ACTION SOLUTION RELAY
[green] [green] Closed
[red] [green]
Corrosion rate
too high
‘ALARM
IGNORE’
= 3 days no
alarm
Identify and repair the
cause Open
[o] [red] Sensor problem Contact technician,
check error code Open
[red] [red]
Corrosion rate
too high
and probe tip
used up
Identify and repair the
cause
and replace probe
Open
[green] [red] Probe tip used up Replace probe Open
[o] [o]
Sensor not connected
or faulty
Check power
supply Replace data logger Open
or SENSOR LED blinks 1x per 2 sec on
CORROSION LED blinks 1x per 8 sec o
LED does not blink
or
‘alarm ignore’ button has been pushed
SENSOR LED blinks 2x per 2 sec on
CORROSION LED blinks 1x per 4 sec o
(*) (**)
(*) Problem with the
central heating
(**) Sensor problem
MINI-USB
(power/data) DATA LOGGER
SENSOR LED
RELAY
ALARM
PROBE
PROBE TIP
ALARM IGNORE
CORROSION
LED
[green]
[green] [red]
[red]

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2. The ‘ALARM IGNORE’ button deactivates the alarm for 3 days.
3. The ‘MINI-USB’ output has two functions:
- standard: connecting the data logger with the mains by means of
a USB mains adapter;
- exception: downloading the measuring data (see Chapter 9)
using a USB/mini-USB data cable (see Chapter 14).
This should be carried out by the service technician/installer.
■ 9 READING
1. The measurement data can be read out periodically, at the earliest 7
days after start up (see also 7.2 Activation).
CAUTION! This should be undertaken out by the service technician/
installer.
2. Install the dashboard software.
3. Disconnect the power supply from the data logger and connect the mini-
USB connector with a PC using a separate (standard) USB/mini-USB
data cable (see Chapter 14).
4. The measurement data can be read, as well as the data for the further
analysis of alarms.
In case of connection with a PC: follow the instructions in the dashboard.
5. Don’t forget to re-connect the power to the data logger afterwards.

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■ 10 REPLACEMENT
If a fault occurs, or when the probe tip has degraded, the probe must be
replaced.
PRESSURELESS REMOVAL OF THE OLD PROBE
In the absence of pressure, the old probe can simply be unscrewed, i.e.
the reverse of screwing it in during the initial assembly (see chapter 6,
Installation).
The replacement of the probe must be undertaken with the
necessary caution by a qualied person.
PRESSURELESS INSTALLATION OF A NEW PROBE
If the system is not under pressure (or at least the section where the probe
is installed), the new probe can simply be screwed in as described earlier for
the initial assembly (see Chapter 6, Installation).
REPLACEMENT UNDER PRESSURE
If the system cannot be made free of pressure, it is possible to replace the
probe by using a Retractor (see Chapter 14).
■ 11 DISMANTLING
At the end of the service life of the probe, the logger and probe should
be taken out of service and the probe replaced. See Chapter 10 for the
dismounting of the probe.
The replacement of the probe must be undertaken with the
necessary caution by a qualied person.

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■ 12 REMARK
The corrosion monitor will stop measuring when the power supply cable
is removed. The previously recorded data will be retained. When the power
cable is reconnected, the measurements simply continue.
■ 13 TECHNICAL DATA
13.1 FUNCTIONAL
• Sensor for continuous monitoring and signalling if there is a risk of
excessive corrosion
• Autonomy of the memory: ten years
• Measurement frequency: every twenty minutes
• Logging frequency: every seven hours
• Output signal:
- visual: LED - see 8.1 LEDs
- USB port- see 9 READING
- Relay: alarm in case of - see 7.4
• Integrated temperature compensation
13.2 MAINS ADAPTER
• Mains voltage: 100...240 VAC
• Mains frequency: 50...60 Hz
• Maximum power: 7,5 W
• Eciency level VI
• Short Circuit Protection/ Over Voltage Protection/ Over Current
Protection
• Mini-USB plug
• Output voltage: 5 VDC
• Maximum output current: 1.5 A
• Temperature:
- Operating temperature: 0 °C...+40 °C
- Storage temperature: -20 °C...+80 °C

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13.3 SENSOR LOGGER AND PROBE
• Power supply voltage: 5 VDC (mini-USB)
• Power consumption:
Average consumption: 29 mA (including relay)
Peak consumption (during measurements): 78 mA (including relay)
• Relay output to break an external circuit,
nominal 24 VDC/VAC, 100 mA (max. 48 VDC/VAC, 2A, 60W)
• Probe pressure range: 0-6 bar
• Probe temperature range:
Measuring range: 5 °C...+85 °C
Operating range: 15 °C...+95 °C
• Probe storage temperature: 0 °C...+35 °C
• Probe air humidity: 20...90% RH, without condensation
13.4 DIMENSIONS / WEIGHT
SENSOR:
• logger: 90 mm * 100 mm * 35 mm
• probe: Ø20 mm * 135 mm
• threaded connection: Ø34 mm * 70 mm with R 1/2” screw thread
• mains adapter: 56 mm * 49 mm * 71 mm (power cord length 1.5m)
PACKAGING:
• dimensions: 256 mm * 192 mm * 64 mm
TOTAL WEIGHT:
• 680 g

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■ 14 ACCESSORIES
14.1 USB CABLE
A standard data cable USB/mini-USB is used to read the data logger
(not included in the package but commercially available).
14.2 RETRACTOR
The Retractor is used to replace the probe under pressure. See the Retractor
manual.
Enter the date of rst use here: / /
Name of the installer:
Tel. no. of the installer:

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If a problem occurs,
please contact Sentinel.
www.sentinelprotects.com
Tel [phone]