tekmar 263 Boiler Control User Manual
Page 6
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Section B: Boiler Operation
Section B1
Boiler
Operation
Section B2
Mode 1
Two Stage
Operation
Section B3
Mode 2
Modulating
Boiler Operation
Section B1: Boiler Operation
BOILER TARGET TEMPERATURE
The boiler target temperature is determined by the type of demand received by the control. A boiler demand calculates a boiler
target based on the characterized heating curve settings and the outdoor air temperature. A DHW demand and a Setpoint demand
have temperature settings to which the boilers are operated to meet.
The control displays the temperature that it is currently trying to maintain as the boiler supply temperature. If the control does not
presently have a requirement for heat, it does not show a boiler target temperature. Instead, “– – –” is displayed in the LCD.
BOILER MINIMUM
The boiler minimum is the lowest temperature that the control is
allowed to use as a boiler target temperature. During mild conditions,
if the control calculates a boiler target temperature that is below the
Boiler Minimum
setting, the boiler target temperature is adjusted to at
least the Boiler Minimum setting. During this condition, if the boiler(s) is
operating, the minimum segment is turned on in the display when viewing
either the boiler supply temperature or the boiler target temperature. Set
the Boiler Minimum setting to the boiler manufacturer’s recommended
temperature.
BOILER MAXIMUM
The boiler maximum is the highest temperature that the control is
allowed to use as a boiler target temperature. If the control does target
the Boiler Maximum setting, and the boiler temperature is near the boiler
maximum temperature, the maximum segment will be displayed in the
LCD while either the boiler target temperature or the boiler temperature
is being viewed. At no time does the control operate the boiler(s) above
248°F (120°C).
FIRE DELAY
The Fire Delay is the time delay that occurs between the time that the control
closes a stage contact to fire a stage and the burner fires for that stage.
MIN Segment On
MAX Segment
On
MAX Segment
On
Boiler
Contact Closes
Boiler
Fires
Fire
Delay
Time
Section B2: Mode 1 - Two On / Off Stages Operation
STAGING
When operating in mode 1, the control operates up to two on / off stages in order to provide the required supply temperature. After
a stage is turned on in the firing sequence, the control waits for a minimum time delay. The minimum time delay is adjustable using
the Stage Delay setting. After the Stage Delay has expired, the control 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 temperature. The colder the supply water temperature,
the sooner the next stage is turned on.
Integral
compares the actual supply temperature to the boiler target temperature over a period of time.
Derivative
compares 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.