tekmar 284 Boiler Control - Manual (Page 19)

© 2014 284_D - 08/14 19 of 60 A Watts Water Technologies Company
Stand-by Pump Operation
ON
Failed
Flow Proof Delay --------------------------------- ---------------------------------
The control waits a period of time to receive a flow proof call
from the time the primary pump turns on. If the control does
not receive a flow proof call within that period of time, the
primary pump turns off & the stand-by primary pump (if active)
turns on. The control then waits that period of time again for
the stand-by primary pump to prove flow. If flow is not proven,
the stand-by pump turns off. The period of time is set through
the FLW PROOF item in the Setup menu & it is adjustable
between 10 seconds & 3 minutes.
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 call 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 flow proof call error will latch
when this condition exists.
Primary Pump Rotation--------------------------- ---------------------------
The control rotates the pumps based on the primary pump
Rotate item in the Setup 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
& rotation is required, the control shuts off the lead pump & 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 call input is checked after the
flow proof call delay time.
Primary Pump Purge ----------------------------- -----------------------------
After the last valid call is removed, the primary pump is operated
for an additional period of time. If the last call 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 & turn off the primary pump. If the last call came from
a non-tN4 zone, the purge period for the primary pump is
adjustable between 10 seconds & 20:00 minutes.
Boiler Pump / Valve Operation -------------------- --------------------
The control includes relays to operate the boiler pumps /
valves.
The control includes a boiler pre-purge which operates the
respective pump / valve for a period of time before the boiler
is ignited in order to purge potential residual heat out of the
boiler. For isolation valves, this time also allows for the valve
to spring open prior to boiler ignition. For pumps, the time is
determined from the boiler mass setting. As the boiler mass
setting is increased, the time is also increased. For DHW and
Setpoint Calls, to help reduce boiler pick-up times, the time
is fixed at 4 seconds. For isolation valves, the time is always
fixed at 30 seconds.
The control includes a boiler post-purge feature that operates
the respective pump / valve for a period of time after the boiler
is turned off. This feature will purge heat out of the boiler &
aid in reducing “kettling”. The amount of time for the boiler
post-purge is adjustable between 10 seconds & 20:00 minutes.
The period of time is adjustable through the boiler post-purge
setting in the Source (#) Menu.
Indirect DHW (IDHW) Pump Operation ------------ ------------
The control includes a relay to operate an indirect DHW
pump.
Operation of the IDHW pump is determined by the Application
Mode & the presence of an appropriate call.
Application Mode: Outdoor Temperature Reset,
Setpoint, Energy Management System
DHW Call from Contact Closure.
DHW Call from DHW Sensor.
DHW Call from tekmarNet
® Setpoint Control with Sensor.
Application Mode: Building Automation System
BAS DHW Pump Call.
DHW Recirculation Pump Operation -------------- --------------
The control has the capability to operate a DHW Recirculation
Pump when the control is configured for either Indirect
Domestic Hot Water (IDHW) or Dedicated Domestic Hot
Water (DDHW). IDHW is available when the application
mode is set to either outdoor temperature reset, setpoint or
EMS. DDHW is available when the applicable mode is set
to DDHW. The Aux Relay setting in the Setup Menu must
be set to DHWR to enable the DHW recirculation pump.
The DHW recirculation pump operates continuously during the
Occupied period. If setback is enabled, the pump operates
when heat is required during the Unoccupied period.
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