IM-P405-39 AB Issue 4
10
Installation A
3. System overview
The BT1050 controls the opening and closing of a valve at the bottom of the boiler to
remove precipitated solids that could otherwise build up, eventually causing damage.
Each BT1050 has three timers. Three timer sequences are available. Only one timer
sequence can be allocated to any one day.
The timers are also used to prioritise boiler blowdown cycles. This:
- allows recovery time (for water in a blowdown vessel to cool),
- minimises waste of heat and water,
- selects the most suitable blowdown time (i.e. avoiding peak steam demand times).
Up to nine BT1050 units can be installed and linked for multi-boiler installations, preventing
more than one boiler blowing down at a time. This feature avoids the possibility of overloading
a blowdown vessel, which could lead to water being discharged to drain at too high a
temperature.
Inputs
The timer is connected directly to the mains supply.
Function / output
When a blowdown is due, a relay energises to open the bottom blowdown valve for the
duration selected. After this, the valve closes until the next blowdown cycle.
If the blowdown valve is fitted with a switch box, an alarm relay can be released if the valve fails
to open or to close within a set time (see Commissioning - Section 6.3.9, 'Alarm sub-menu').
SUN
MON
TUE
WED
THU
FRI
SAT
TIMER 1
sequence
SUN
MON
TUE
WED
THU
FRI
SAT
TIMER 2
sequence
CLOCK - 24 hrs
00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 00
Start time = 8:00
Start time = 00:00
Repeat = 01:00
Start time = 8:00
SUN
MON
TUE
WED
THU
FRI
SAT
TIMER 3
sequence
