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11

Common Settings

Stage 1, 2, 3, 4, 5, 6, 7, & 8 Auto or Off switch

When a stage switch is set to "Auto", that particular stage becomes active and its
boiler is available for operation. If the stage switch is "Off", the control will ignore that
stage and not turn it on.

Rotate switch

When this switch is set to "Rotate", the firing order of the stages is changed to even
out wear and tear on the boilers. Whenever one stage accumulates 48 hrs more
running time than the others, it will be rotated to be the last boiler fired and the boiler
with the least amount of running time will become the lead boiler. Whenever the Test
button is pushed, the control automatically re-ranks the firing sequence based on
accumulated running times. When the Rotate switch is set to "Off", the firing order will
always stay the same; 1,2,3,4,5,6,7,8 to stage on, and reverse order to stage off.

Fixed lead switch

When the boilers are to be rotated and this switch is set to "Fixed lead", the stages
are rotated as described above with the exception that Stage 1 will always be the first
boiler to fire and the first boiler to stage off. This feature is commonly used when a high
efficiency lead boiler is used in conjunction with mid efficiency boilers to increase
overall heating plant efficiencies, or when the boiler closest to a chimney needs to be
fired first in order to establish draft in the chimney.

Lo-Hi fire switch

When boilers are to be rotated and Lo-Hi fire boilers are used, the stages must be
rotated in such a way as to prevent possible High fire starts and mixing up of the stages
between boilers. When this switch is set to "Lo-Hi fire", the stages rotate as Lo-Hi fire
pairs (1 & 2 and 3 & 4, etc.) and the hours of use are calculated based on the Lo fire
run times. In addition, the control will not allow a Hi fire stage to operate if its
corresponding Lo fire stage DIP switch has been turned off. (ie. if Stage 1 is turned
off, stage 2 will not be allowed to fire and the control will move on to 3 & 4)

Fixed last switch

When the boilers are to be rotated and this switch is set to "Fixed last", the stages are
rotated as described above with the exception that Stage 8 will always be the last
boiler to fire and the first boiler to stage off. This feature is commonly used to operate
a diverting valve which will allow Domestic Hot Water boilers to be switched over to
assist the heating boilers during peak load times.

Int. timer switch

The 258 control has an internal timer – programmed using the LCD display and
keypad – that can be used to switch up to two Occupied/Unoccupied events per day
on a 7 day basis.
Details on the operation of this timer can be found in the "Programming" section on
page 15.

Ext. timer switch

The 258 control can be switched into the Unoccupied mode by an external signal
when a dry contact closure occurs between terminals

 UnO Sw — Com Sen (26 & 28).

Minimum Supply Temperature

This dial should be set according to the requirements specified by the boiler
manufacturer. Many boilers require a minimum operating temperature to prevent
corrosion from flue gas condensation. The control raises the supply temperature to the
Minimum setting when the outdoor temperature drops below the WWSD point, and
holds it there until the outdoor temperature becomes cold enough to require operation
on the heating curve.

Note:  Many boiler manufacturers requires a minimum return temperature to their
equipment. In systems where this is a strict requirement, the minimum supply
temperature setting should be set to the recommended return temperature plus the
boiler 

T under full load conditions.

Auto

Stage

1   2   3   4   5   6   7   8

Perm.
Demand

Ext. timer

Fixed last

Int. timer

Lo-Hi fire

Fixed lead

Rotate

Off

1

2

3

4

5

6

7

8

9

External
Demand

Off

1

2

3

4

5

6

Stpnt

Reset

Auto

Stage

1   2   3   4   5   6   7   8

Perm.
Demand

Ext. timer

Fixed last

Int. timer

Lo-Hi fire

Fixed lead

Rotate

Off

1

2

3

4

5

6

7

8

9

External
Demand

Off

1

2

3

4

5

6

Stpnt

Reset

Auto

Stage

1   2   3   4   5   6   7   8

Perm.
Demand

Ext. timer

Fixed last

Int. timer

Lo-Hi fire

Fixed lead

Rotate

Off

1

2

3

4

5

6

7

8

9

External
Demand

Off

1

2

3

4

5

6

Stpnt

Reset

Auto

Stage

1   2   3   4   5   6   7   8

Perm.
Demand

Ext. timer

Fixed last

Int. timer

Lo-Hi fire

Fixed lead

Rotate

Off

1

2

3

4

5

6

7

8

9

External
Demand

Off

1

2

3

4

5

6

Stpnt

Reset

Auto

Stage

1   2   3   4   5   6   7   8

Perm.
Demand

Ext. timer

Fixed last

Int. timer

Lo-Hi fire

Fixed lead

Rotate

Off

1

2

3

4

5

6

7

8

9

External
Demand

Off

1

2

3

4

5

6

Stpnt

Reset

Auto

Stage

1   2   3   4   5   6   7   8

Perm.
Demand

Ext. timer

Fixed last

Int. timer

Lo-Hi fire

Fixed lead

Rotate

Off

1

2

3

4

5

6

7

8

9

External
Demand

Off

1

2

3

4

5

6

Stpnt

Reset

Auto

Stage

1   2   3   4   5   6   7   8

Perm.
Demand

Ext. timer

Fixed last

Int. timer

Lo-Hi fire

Fixed lead

Rotate

Off

1

2

3

4

5

6

7

8

9

External
Demand

Off

1

2

3

4

5

6

Stpnt

Reset

Minimum

120

°

F

Off

170

80

Summary of Contents for Eight Stage Boiler Control 258

Page 1: ...mand Minimum WWSD Pump Stage 1 Stage 2 Comb air Stage 3 Stage 6 Stage 5 Stage 8 Stage 7 Stage 4 Menu Item Override Setpoint Actual Supply Target Supply S PRGM TEMP F C TIME USE AMPM UNOCC OVR M T W T...

Page 2: ...ugh water to keep the room temperature warm particularly during the colder weather If the Heating Curve selected is too high the supply water will be too hot for the conditions and the building will o...

Page 3: ...ntrol The effect of the Integral function can also be easily viewed by not allowing a rise in supply temperature when the control asks for more heat The displayed target temperature will show a slow b...

Page 4: ...allow Heating Curve operation System pump light on the system pump relay is on closing the contacts between terminals System Pmp 3 4 Comb air light on the combustion air relay is on closing the contac...

Page 5: ...e Occupied room temperature setting the control enters WWSD When switched into Unoccupied mode the UNOCC display element will replace the OCC display element and the control will switch from operating...

Page 6: ...e Stage and Comb air lights will be shut off with the boilers and combustion air damper The control will continue to cycle the boilers and combustion air damper to maintain the supply at the target te...

Page 7: ...lighter guage wire is too fragile and may also contribute too much resistance to the circuit Power should not be applied to any of the wires during this rough in wiring stage Step Four Electrical con...

Page 8: ...nals Heat Dem 5 and 6 When 24Vac is applied to these terminals the control will recognize a call for heat from the system DIP switch must be set to Reset If a 24Vac Setpoint Demand signal is used aqua...

Page 9: ...powered up the combustion air damper should operate If it does not come on check the circuit wiring for errors and ensure that it is powered up and the voltage is correct Check the devices in the cir...

Page 10: ...e Heating Curve use the following formula Outdoor air temperature Supply water temperature 50 10 30 1 10 12 10 F 23 C 110 43 70 21 70 21 90 32 210 99 170 77 150 65 130 54 190 88 3 6 3 0 2 4 2 0 1 6 0...

Page 11: ...w Domestic Hot Water boilers to be switched over to assist the heating boilers during peak load times Int timer switch The 258 control has an internal timer programmed using the LCD display and keypad...

Page 12: ...tback and delivering cold water to the boilers increased load Typically this will cause many or all of the boilers to be staged on with minimum delay which is the correct control action for the situat...

Page 13: ...ustion air damper will remain open After the 5 minutes the control will automatically exit the test routine and enter the normal operating mode If there is no Heat Demand the control will not allow a...

Page 14: ...ply temperatures and the LED system status lights display the operation of the various system components A competent troubleshooter can locate system faults without having to go any further than obser...

Page 15: ...tual Supply Target Supply F S TEMP OCC S M W T F T Auto Stage 1 2 3 4 5 6 7 8 Perm Demand Ext timer Fixed last Int timer Lo Hi fire Fixed lead Rotate Off 1 2 3 4 5 6 7 8 9 External Demand Off 1 2 3 4...

Page 16: ...ress or to change the day pointer PROGRAM MENU VIEWING Must be set to Int timer Auto 1 2 3 4 5 6 7 8 Perm Demand Ext timer Int timer Off 1 2 3 4 5 6 7 8 9 External Demand Off 1 2 3 4 5 6 Stpnt Reset P...

Page 17: ...button when the control is showing a fixed display Setpoint Actual Supply Target Supply F S TEMP S M W T F T OVR UNOCC Which mode is selected See page 3 Menu Item Override Menu Item Override Menu Item...

Page 18: ...nOcc 1 5 00 pm Occ 2 10 30 pm UnOcc 2 Friday 6 00 am Occ 1 8 30 am UnOcc 1 5 00 pm Occ 2 11 30 pm UnOcc 2 Saturday 8 00 am Occ 1 11 30 pm UnOcc 1 Null Occ 2 Null UnOcc 2 Schedule P 5 Day Time Temperat...

Page 19: ...when powered down for up to 10 years Battery backup Maintains clock operation for 24hrs when powered down Dial Switch Settings Heating Curve 0 4 to 3 6 Minimum Off 80 to 170 F Off 27 to 77 C Boiler D...

Page 20: ...antability and fitness for a particular purpose shall not extend beyond 24 months from the date of invoice or 12 months from the date of installation of the product whichever occurs first Replacements...

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