4
Test
Power
Heat
Demand
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 F S
OUTSIDE
ROOM
1
2
Sequence of Operation
258 indicator lights
Heating Operation
The 258 control must have the
Reset/Stpnt selector switch set for "Reset", and must
receive a Heat Demand signal before it can operate in the heating mode.
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
There are eighteen lights on the front of the control that will aid in testing and troubleshooting. During normal operation, these
lights indicate the following functions:
"Power" light on
• the 24Vac power supply has been connected to terminals
Power C – R (1 and 2), and is energized.
"Setpoint" light on
• the Display is showing the programmed setpoint temperature.
"Actual Supply" light on
• the Display is showing the current supply sensor temperature.
"Target Supply" light on
• the Display is showing the control's calculated target supply temperature.
"Heat Demand" light on
• the control is receiving a 24Vac external Heat/Setpoint Demand signal at terminals
Heat
Dem (5 and 6)
or the Heat/Setpoint Demand selector switch is in the "Permanent" position or a 10K Zone Control
is connected and is creating a Heat Demand.
"WWSD" light on
• the control is in the "Reset" mode, the outdoor temperature is above the WWSD point and the
control has shut the heating system off.
"Minimum" light on
• the control has calculated that it must operate the boiler(s) to maintain the Minimum Supply
temperature until the outdoor temperature is cold enough to 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 contacts between terminals
Comb. air (7 & 8).
"Stage 1 to 8" lights on
• a boiler relay is on, closing the contacts between terminals
Stage 1 (9 & 10) , Stage 2 (11 & 12), etc.
"Test" light on/flashing
• the control is going through the programmed test routine/is halted in test routine.
When the Eight Stage Boiler Control 258 is powered-up, the "Power" light will come on and the full display along with all of the red
temperature indicator lights are switched on for approximately 5 seconds. The Display will then default to show the "ACTUAL SUPPLY"
fixed display mode and the control will enter the operating mode. A "fixed display" is one which will show its information continuously,
and the four fixed displays available to the user are illustrated on the previous page. More information on access to displays and on
programming is available in the "Programming" section, starting on page 15.
Once in operating mode, the control uses the Outdoor Sensor 070 to continually monitor the outdoor temperature, and the Universal
Sensor 071 to continually monitor the system supply water temperature.
Indoor temperature can be monitored through the use of a tekmar 10K Zone Control
(Optional; must be ordered separately)
While monitoring these temperatures, the control recognizes a variety of conditions and inputs, and will operate the system as described
below. During operation, the lights on the front of the control – illustrated above – will indicate how the system is operating.
By reading this sequence of operation section and comparing it to what the indicator lights and the L.C.D. display actually show; installers,
end users and maintainance personnel can easily confirm proper system and control operation in the field and make the right corrective
adjustments when necessary.
