tekmar 275 Boiler Control - Manual (Page 18)

© 2012 275_D - 11/12 18 of 48
Flow Proof Demand Test
The control includes a flow proof demand test in order to
determine if the flow/pressure device has failed. A flow
proof failure is detected if a flow proof is present after the
pumps have been shut off for more than four minutes. This
can occur if the flow proof device sticks in the on position
even when flow has stopped in the system. A proof demand
error will latch when this condition exists.
Primary Pump Rotation Setting in Adjust Menu
The control rotates the pumps based on the Rotate item
in the Adjust menu. Frequency of Rotation is based on the
running time of the pumps. Rotation is done when the lead
pump is off. If the lead pump runs continuously, the rotation
is delayed for up to 12 hours. If the pump runs continuously
and rotation is required, the control shuts off the lead pump
and 1 second later the stand-by pump is turned on. This
eliminates overloading the pump electrical circuit. Upon
turning on the stand-by pump the flow proof input is checked
after the flow proof demand delay time.
Primary Pump Purge
After the last valid demand is removed, the primary pump
is operated for an additional purging time of at least 20
seconds. If the last demand came from a tN4 zone, the
control sends out a purge message to override the zone
open for the duration of the boiler purge. At the end of
the purge, the zone override is removed so the zone is
allowed to close and turn off the primary pump. If the last
demand came from a non-tN4 zone, the purge period for
the primary pump is adjustable between 10 seconds and
19:55 minutes.
Boiler Pump Operation
The control is capable of operating individual boiler pumps.
This feature is available by setting the Boiler relays to pump
in the Adjust Menu.
The control includes a boiler pump pre-purge which operates
the respective boiler pump for a period of time before the
boiler is ignited in order to purge potential residual heat out
of the boiler. The pre-purge time is determined from the
boiler mass setting. As the boiler mass setting is increased,
the boiler pump pre-purge time is also increased. The
pre-purge time is fixed at 4 seconds whenever a DHW /
Setpoint demand is provided in order to reduce boiler pick-
up times.
The control includes a boiler pump post-purge feature that
operates the respective boiler pump for a period of time
after the boiler is turned off. This feature will purge heat out
of the boiler and aid in reducing “kettling”. The amount of
time for the boiler pump post purge is adjustable between
10 seconds and 19:55 minutes. See the boiler pump purge
setting in the adjust menu.
Combustion Air and Alert Settings Section M
Relay Setting in Adjust Menu (C.A. / Alert)
The control includes an auxiliary relay that can be used
either for a combustion / venting device or an Alert. Selection
is made through the Relay item in the Adjust menu.
Alert
When the Relay is set to Alert, terminals 21 and 22 close
whenever a control or sensor error is detected, or when a
warning or limiting condition is detected. When the alert
contact closes, refer to the Error Messages section of this
brochure to determine the cause of the alert and how to
clear the error.
Boiler Alarm
For the Boiler Alarm item to appear in the Adjust menu,
the Relay must be set to Alert. If no temperature increase
is detected at the boiler supply sensor within this delay
period, the Alert relay will close and the control will display
the Boiler Alarm error message. To clear the error, press
and hold the up and down buttons together for 5 seconds
while viewing the error message in the View menu.
Combustion Air (C.A.)
When the Relay is set to C.A., terminals 21 and 22 operate
a combustion air damper / fan motor or power vent motor.
The Relay closes once a demand is received and the
control has determined that one or more boilers need to
be turned on.
Combustion Air Proof Demand Setting in Adjust Menu
The proof demand can be used to prove a combustion air
or venting device if set to C.A. Boiler operation cannot occur
until the proof demand is present. If the proof demand is
lost during operation, the boiler plant is sequenced off.
Combustion Air Proof Demand Delay Setting in
Adjust Menu
The control includes a time delay that is associated with
the proof demand feature in order to determine if the proof
device is functional. Once the C.A. relay closes, the control
allows for this delay to receive the proof demand. If the proof
demand is not received within the delay time, the control
will display an error message.
Combustion Air Delay Setting in Adjust Menu
If the Proof Demand function is set to F P (flow proof) or
OFF, sequencing only occurs once a user adjustable time
delay elapses.
Combustion Air Post Purge
There is a fixed 15 second post purge of the C.A. relay
after the last boiler has turned off, or demand is removed. If
there is a heat demand still present once the last boiler has
turned off, the control can look at the error and determine
if sequencing is to occur in a “short” period of time. If the
control does anticipate staging, the C.A. relay will remain
on. Otherwise, the C.A. relay will be turned off once the 15
second post purge elapses.