tekmar 262 Boiler Control Installation - Manual (Page 4)

4 of 36 Copyright © D 262 -
12/08
Section A —General Operation
POWERING UP THE CONTROL
When the Boiler Control 262 is powered up, the control displays the control type number in the LCD for 2 seconds. Next, the software
version is displayed for 2 seconds. Finally, the control enters into the normal operating mode and the LCD defaults to displaying the
current outdoor air temperature.
MODES OF OPERATION (MODE)
The Boiler Control 262 has two operating modes. The mode of operation
for which the control is to operate is selected in the
Adjust Menu.
Mode 1 (MODE = —1—)
Mode 1 is designed for one or two stages of Heating, Domestic Hot
Water (DHW), and Setpoint operation.
Mode 2 (MODE = —2—)
Mode 2 is designed for dedicated DHW operation. In this mode, the 262
controls one or two stages of heat for DHW generation (see Section C3
Dedicated DHW).
STAGING
The 262 controls up to two stages in order to supply the required target
temperature. After each stage is turned on in the firing sequence, the
control waits a minimum amount of time before turning on the next stage.
The minimum time between stages is the total of the fire delay (FIRE DLY)
setting plus the minimum inter-stage delay selected by the boiler mass
(Boil MASS) setting. After the minimum time delay between stages has
expired, the 262 examines the control error to determine when the next
stage is to fire. The control error is determined using Proportional, Integral,
and Derivative (PID) logic.
Proportional - compares the actual supply temperature to the boiler target
(Boil TRG) temperature. The colder the supply water temperature, the
sooner the next stage is turned on.
Integral - compares the actual supply temperature to the Boil TRG
temperature over a period of time.
Derivative - determines how fast or slow the supply water temperature is
changing. If the supply temperature is increasing slowly, the next stage is
turned on sooner. If the supply temperature is increasing quickly, the next
stage is turned on later, if at all.
Each stage has a minimum on time and a minimum off time.
FIRE DELAY (FIRE DLY)
The Fire Delay is the delay time that may occur between the time that the
262 closes a stage contact and the burner fires for that stage. This delay
is usually the result of burner pre-purge or other forms of time delay built
into the burner’s safety circuits.
BOILER MASS (Boil MASS)
The Boiler Mass setting allows the installer to adjust the control to the
thermal mass of different types of heat sources used.
Sequence of Operation
Section A
General Operation
Page 4 - 6
Section B
Boiler Reset
Page 6 - 10
Section C
Domestic Hot
Water (DHW)
Page 10 - 12
Section D
Setpoint
Page 12
Boiler T
emperature
Time
Boiler #1
Boiler #2
Fire
Delay
Fire
Delay
Interstage Delay
Boiler #1 Fires
Boiler #2 Fires
Boiler Contact Closes
Boiler T
emperature
Time
Fire
Delay
Fire
Delay
Boiler Contact Closes
Boiler Fires
Minimum
Off Time
Minimum On Time Minim
Boiler
Sensor
P
DHW
Pump
Boiler
Pump