tekmar 284 Boiler Control - Manual (Page 5)

© 2014 284_D - 08/14 5 of 60 A Watts Water Technologies Company
System Setup & Operation
Application Mode -------------------------------- --------------------------------
There are five possible application modes that the 284 can be
configured for including:
Outdoor Temperature Reset (RSET)
Fixed Setpoint (SETP)
Dedicated Domestic Hot Water (DDHW)
Energy Management System (EMS)
Building Automation System (BAS)
Refer to the appropriate section of this brochure for a description
of the each of the application modes.
Boiler Minimum ---------------------------------- ----------------------------------
The Boil MIN 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. MIN is displayed
in the status field while viewing the boiler supply or target &
when the boiler target is boiler minimum & the boiler supply
is less than boiler minimum plus 5°F (2.5°C). Set the Boiler
Minimum setting to the boiler manufacturer’s recommended
temperature.
The Boil MIN is only applicable when at least one of the
boilers is configured for non-condensing.
Boil MIN
MIN segment on
Boil MIN + 5°F (2.5°C)
Boiler Differential
Boil
Water Tempe
rat
ur
e
Boil
Water Tempe
rat
ur
e
Boil
Water Tempe
rat
ur
e
Boiler Maximum ---------------------------------- ----------------------------------
The Boil MAX is the highest temperature that the control is
allowed to use as a boiler target temperature. MAX is displayed
in the status field viewing the boiler supply or target & when the
boiler target is boiler maximum & the boiler supply is greater
than boiler maximum minus 5°F (2.5°C). Set the boiler maximum
setting below the boiler operator or aquastat temperature.
Boil MAX
Boil MAX – 5°F (2.5°C)
Boiler Differential
MAX
segment
on
MAX
segment
on
B
o
il
W
a ter Te m
pe
ra
tu
re B
o
il
W
a ter Te m
pe
ra
tu
re B
o
il
W
a ter Te m
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re
Boiler Differential -------------------------------- --------------------------------
Both on/off (single stage & two stage) & modulating boilers are
operated with a differential. In some cases, a modulating boiler
must be operated with a differential at low fire. This indicates
the load is smaller than the minimum modulation of the boiler.
For modulating boilers, the differential no longer applies once
operating the boiler above low fire.
The differential operates by turning on the boiler when the
boiler supply water temperature is 1/2 of the differential below
the boiler target temperature. As the boiler supply water
temperature reaches 1/2 of the differential above the boiler
target temperature, the boiler is shut off.
•
•
•
•
•
Manual Differential
Differential = 10°F (6°C)
Target + 1/2 Differential
Target – 1/2 Differential
Target
165°F (74°C)
160°F (71°C)
155°F (68°C)
Boiler
On
Boiler
On
Automatic Differential
Off
Differential
Time
Heating Load
On
Exercising ---------------------------------------- ----------------------------------------
The control will exercise all pumps, & tN4 zones (zone valves
& zone pumps) for 10 seconds every three days of inactivity
to prevent seizure. To enable exercising, switch the Exercise
/ Off DIP to the Exercise position.
Boost -------------------------------------------- --------------------------------------------
When the control changes from the UnOccupied mode to the
Occupied mode, it enters into a boosting mode. In this mode,
the supply water temperature to the system is raised above its
normal values for a period of time to provide a faster recovery
from the setback temperature of the building. The maximum
length of the boost is selected using the BOOST setting in
the Setup menu.
Typical settings for the boost function vary between 30 minutes
& two hours for buildings that have a fast responding heating
system. For buildings that have a slow responding heating
system, a setting between four hours & eight hours is typical.
After a boost time is selected, the setback timer must be
adjusted to come out of setback some time in advance of the
desired occupied time. This time in advance is normally the
same as the BOOST setting.
If the building is not up to temperature at the correct time, the
BOOST setting should be lengthened & the setback timer should
be adjusted accordingly. If the building is up to temperature before
the required time, the BOOST setting should be shortened &
the setback timer should be adjusted accordingly. If the system
is operating near its design conditions or if the supply water
temperature is being limited by settings made in the control,
the time required to bring the building up to temperature may
be longer than expected.