BC3250 Blowdown Controller
Local regulations may restrict the use of this product to below the conditions quoted.
In the interests of development and improvement of the product, we reserve the right to change the specification without notice. © Copyright 2015
AB Issue 5
Blowdown Controller
The BC3250 is a blowdown controller for steam boilers. It controls
TDS (total dissolved solids - salts in solution) by opening and
closing a blowdown valve.
It also has a timer that controls a bottom blowdown valve, to remove
precipitated solids from the bottom of the boiler.
The product works in conjunction with a Spirax Sarco conductivity
sensor, a boiler blowdown valve and, for condensate contamination
detection, a dump valve.
It can operate on a supply voltage of between 110 to 240 Vac at
50 / 60 Hz.
The front panel has an LCD graphics display and five-button
keypad to select, view, and change functions.
In run mode (standard setting) the display is divided into three
i) Process variable and control parameters.
ii) Information line, displays the various control states and process
iii)Three bar graphs, which show a percentage of full scale of:
- PV Process Variable highest and lowest recorded value.
- SP Set Point and hysteresis point.
- AL High Alarm and hysteresis point.
An additional filter can be selected to increase the damping effect
where the probe is fitted directly in the boiler. This avoids overfrequent valve operation.
A Trend graph screen display appears if the right or left button is
pressed in run mode - This displays a record of the variation in
TDS over a set time.
The BC3250 can be used on a condensate contamination system.
Please note that it will not detect contaminants that do not change
the conductivity, e.g. oils, fats, or sugars.
The blowdown may be set to pulsed, rather than continuous output,
opening for 10 seconds, and closing for 20 seconds. This avoids
the risk of triggering a low water alarm in smaller boilers.
An isolated 0 - 20 or 4 - 20 mA output is provided for remote display
of the TDS level or as an output to a management system.
If a switch box is fitted to the bottom blowdown valve actuator, an
alarm can be configured to indicate if the bottom blowdown valve
fails to close or to lift off its seat.
The BC3250 can communicate via an infrared link between
adjacent controllers. It can be designated as either a master unit
or a slave unit.
The unit can be panel, DIN rail or chassis mounted.
Principal features:
- Blowdown controller with bottom blowdown timer.
- Multi-voltage 110 Vac to 240 Vac.
- UL and TÜV approved.
- Display in µS / cm or ppm.
- LCD graphics display of PV and sequential trend graph.
- Filter for turbulent conditions.
- Infrared communications.
- Diagnostic / test facility.
- 0/4 - 20 mA output.
- EIA 485 / Modbus communications.
5 button
This product complies with the Electromagnetic Compatibility
Directive 2004 / 108 / EC and all its requirements.
The BC3250 is suitable for Class A Environments (e.g. industrial).
A fully detailed EMC assessment has been made and has the
reference number UK Supply BH BC3250 2008.
The BC3250 complies with the Low Voltage Directive by meeting
the standards of:
- EN 61010-1:2010 safety requirements for electrical equipment
for measurement, control, and laboratory use.
The BC3250 has been type-tested as a TDS controller by meeting
the standard:
- Vd TÜV requirements for TDS control device, Water Level 100
- UL listed (open)
The BC3250 can accept a signal from a Spirax Sarco CP10, CP30
or CP32 conductivity probe, and a Pt100 temperature sensor.
Function / outputs
If the water conductivity exceeds the Set Point, the valve relay will
be energised until the conductivity drops below the Set Point.
If the water conductivity exceeds the alarm level, the alarm relay
will be de-energised until the conductivity drops below the alarm
Other features:
- Test function.
- Direct display of probe factor.
- Commissioning parameters protected with a pass code.
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Technical data BC3250
Power supply
Mains voltage range 110 Vac to 240 Vac at 50 / 60 Hz
Power consumption 7.5 W (maximum)
General Indoor use only
Maximum altitude 2 000 m (6 562 ft) above sea level
Ambient temperature limits 0 - 55°C
Maximum relative humidity 80% up to 31°C decreasing linearly to 50% at 40°C
Overvoltage category III
Pollution degree
2 (as supplied)
Enclosure rating
(front panel only)
LVD (safety)
NEMA type 4 hose down only (UL approval) and
IP65 (verified by TRAC Global)
Electrical Safety EN 61010-1
UL61010-1, 3rd Edition, 2012-05 CAN/CSA-C22.2 No. 61010-1, 3rd Edition, 2012-05
Immunity / Emissions
Colour Pantone 294 (blue)
Material Silicone rubber, 60 shore.
3 (when installed in an enclosure) - Minimum of IP54 or UL50 / NEMA Type 3, 3S, 4, 4X, 6, 6P or 13.
Front panel
Solder Suitable for heavy industrial locations
Tin / lead (60 / 40%)
Rising clamp plug-in terminal blocks with screw connectors. TerminationCaution: Use only the connectors supplied by Spirax Sarco Ltd. Mains
Safety and Approvals may be compromised otherwise.
and signal
Cable size
Stripping length 5 - 6 mm
High temperature
Shield type
Number of cores
1 – 1.5 mm² (18 - 16 AWG)
TDS cable / wire
0.2 mm² (24 AWG) to 2.5 mm² (12 AWG).
0 - 9.99 range - 10 metres
Maximum length
0 - 99.90 range - 30 metres
0-999.0 range and 0-9990 ranges - 100 metres
Recommended type
Prysmian (Pirelli) FP200,
Delta Crompton Firetuf OHLS
High temperature, twisted
Shield type
Pt100 probe cable / wires
Number of cores
1 – 1.5 mm² (18 - 16 AWG)
Maximum length 100 m (328 ft)
Twisted pair
Shield type
0/4-20 mA output(s) Number of pairs
cable/wire Gauge
Maximum length 1
0.23 - 1 mm² (24 - 18 AWG)
100 m (328 ft)
Recommended type
EIA RS485 twisted pair
RS485 communication
cable / wire
Shield type
Number of pairs
2 or 3
0.23 mm² (24 AWG)
Maximum length 1200 m (4000 ft)
Recommended type
Alpha Wire 6413 or 6414
LAN Cat 5 or Cat 5E ScTP (screened), FTP (foil) or STP (shielded) cable can be used, but limited to 600 m.
TI-P403-90 AB Issue 5
BC3250 Blowdown Controller
Page 2 of 4
Technical data BC3250 (continued)
Probe typesCP10, CP30 and CP32
Ranges0 – 99.9 ppm or µS/cm
0 – 999 ppm or µS/cm
Minimum ≥ 1 µS @ 25°C
0 – 9.99 ppm or µS/cm
0 – 9990 ppm or µS/cm
± 2.5% FSD (Poss > if high EMC)
pH factor
0.50 – 1.00 (0.7 default)
Neutralising factor
Resolution0.1% FSD
Drive:ac – 4 wires
Sensor typePt100 – Class B or better
(With Pt100 not fitted – Range0 - 250°C
user programmed temperature 100 - 250°C, 1°C steps)
± 2.5% FSD – system accuracy ± 5%
compensation Accuracy
Resolution1% FSD
Drive:dc – 3 wires
Input voltage range
110 – 240 Vac
Maximum current input
2 mA maximum
Maximum voltage 32 Vdc
Burner input
Probe cleaning
Driveac /dc /pulsed
Minimum current
0 mA
Maximum current
20 mA
Open circuit voltage 19 Vdc
1% FSD
Maximum output load
500 ohm
Isolation 100 V
Output rate 10 / second
Contacts 2 x single pole changeover relays (SPCO)
4 - 20 mA Voltage ratings (maximum)
Resistive load
Inductive load
ac motor load
1 amp @ 250 Vac
Pilot duty load
C300 (2.5 amp) - control circuit / coils
Electrical life (operations)
3 x 10 5 or greater depending on load
Mechanical life (operations)
30 x 10 6
Physical layer RS485 4-wire full or 2-wire half duplex
Protocol Modbus RTU format
Isolation 60 Vac/dc
Receiver unit load (256 devices - maximum)
Output rate Up to 10 frames / second
250 Vac
3 amp @ 250 Vac
¼ HP (2.9 amp) @ 250 Vac
/10 HP (3 amp) @ 120 Vac
Physical layer IrDA
38 400
10 cm
Working angle
Eye safety information
TI-P403-90 AB Issue 5
Exempt from EN 60825-12: 2007 Safety of laser products - does not exceed the accessible emission limits (AEL) of Class 1
BC3250 Blowdown Controller
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Safety information, installation and maintenance
Warning: This document does not contain sufficient information to install the unit safely. The unit operates at a potentially
fatal mains voltage. Before attempting to install the unit read the Installation and Maintenance Instructions supplied with it.
The product must be installed in a suitable industrial control panel or fireproof enclosure to provide impact and environmental protection.
A minimum of IP54 (EN 60529) or Type 3, 3S, 4, 4X, 6, 6P and 13 (UL50/NEMA 250 ) is required.
The product may be installed on a DIN rail, a chassis plate, or in a panel cut-out. A bezel is supplied.
Install the product in an environment that minimises the effects of heat, vibration, shock and electrical interference.
Do not install the product outdoors without additional weather protection.
Do not attempt to open the product - it is sealed and has no replaceable parts or internal switches.
Do not cover or obstruct the infrared beam between products.
Your attention is drawn to IEE Regulations (BS 7671, EN 12953, EN 12952 and EN 50156). Elsewhere, other regulations will normally
All wiring materials and methods shall comply with relevant EN and IEC standards where applicable.
No special servicing, preventative maintenance or inspection of the product is required.
Boiler water level controls and level alarms do, however, require testing and inspection. General guidance is given in Health and Safety
Executive Guidance Notes BG01 and INDG436.
Dimensions / weight (approximate) in mm and g.
Weight 550 g.
52 mm
120 mm
140 mm
120 mm
How to specify
Blowdown controller with integral bottom blowdown timer and infrared comms.
How to order
Example: 1 off Spirax Sarco BC3250 blowdown controller.
TI-P403-90 AB Issue 5
BC3250 Blowdown Controller
Page 4 of 4
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