tekmar 269 One Stage Steam Control - Manual (Page 5)

Copyright © D 269 - 06/00 5 of 12
Auxiliary Relay function
The control turns on the "Auxiliary" light and closes the "Aux." relay contacts whenever it is not in WWSD. This relay can be used
for a variety of functions such as turning on a condensate pump or other auxiliary device(s), disconnecting power to the burner for
the summer and/or signalling to remote monitoring equipment that the heating system is enabled.
Warning Relay function
The control turns on the "Warning" light and closes the "Warn." relay contacts whenever an error message is generated due to
sensor failure. This relay can be used to turn on an alarm or other auxiliary device(s) or signal to remote monitoring equipment that
the control system has a fault and is in need of repair.
Lockout Differential function
Many steam systems require a Lockout (cool
down) period before each on cycle to ensure
that any remaining steam in the system
condenses and the condensate has time to
return to the boiler. This increases the effi-
ciency of the system by removing the latent
heat from steam remaining after the burner
shutdown, and lengthening the cycle so that
the remaining heat is allowed to radiate into
the building. When using a Condensate Sen-
sor, the "Min. On Time (%)" dial becomes the
"Lockout Diff'l (
°F)" dial, and if the Conden-
Early Start DIP switch = on
Early Start Condensate Return Sensor
Indoor Sensor S2
Indoor Sensor S1
1 2 3 4
Off
When the "Early Start" DIP switch is in the up position, the control must receive an UnOccupied
signal
4 hours before the building is to be in UnOccupied mode and the UnOccupied signal
must be removed 4 hours before the building is to be back up to the Occupied temperature.
Going into Unoccupied
After receiving the Unoccupied signal, the control will calculate when to turn on its "Early Start" light based on the Cycle Length
setting. During the Early Start period, the boiler will be kept off so that the room temperature will begin to fall by the time the
Unoccupied period begins. At the beginning of the Unoccupied period, the "UnOcc." light will turn on and the "Early Start" light will
turn off. The "UnOccupied" dial setting becomes the new WWSD point. When one or two Indoor Sensors are connected, the
"UnOccupied" dial setting is still the WWSD point, but the Heating Curve and WWSD point can be shifted down by the room
temperature feedback to prevent overheating.
See Indoor Sensor 074 function, and Figures 6 and 7, page 3. When the outdoor
temperature is above the UnOccupied dial setting, the control will go into WWSD when put into the UnOccupied mode, and the
WWSD light will come on.
Going out of Unoccupied
When the UnOccupied signal is removed from terminals Com Sen — UnO Sw (10 and 11), the control will calculate when to start
bringing the building out of setback based on the outdoor temperature and the amount and duration of the setback. At the time the
control has calculated for the "Early Start" period to begin, it will turn on its "Early Start" light and operate the boiler for an increased
% on time in order to have the building up to temperature at the start of the Occupied period. Four hours after the UnOccupied signal
has been removed, the control will turn off the "Early Start" and "UnOcc." lights and resume a normal % on time based on the outdoor
temperature. See Figure 10 on page 6. If one or two Indoor Sensor 074s are connected to the control, and the indoor temperature
is above the "Occupied" dial setting, the boiler will not be turned on for an Early Start period as Early Start will not be needed. In
colder weather the boiler may run almost continually during the Early Start period in order to recover the building temperature.
Without Early Start feature
The control turns on its "UnOcc." light and starts to go into the UnOccupied mode
whenever terminals
Com Sen — UnO Sw (10 and 11) are shorted together. When
there are no Indoor Sensor 074s connected to the control, the "UnOccupied" dial
setting becomes the WWSD point. When one or two Indoor Sensors are connected,
the "UnOccupied" dial setting is still the WWSD point, but the Heating Curve and
WWSD point can be shifted down by the room temperature feedback in order to
prevent overheating.
See Indoor Sensor 074 function, and Figures 6 and 7, page 3.
Note: When the outdoor temperature gets close enough to the design outdoor
temperature (approximately 85% on time), the control is prevented from going
into the UnOccupied mode in order to avoid long pick-up times. If the control
is already in the UnOccupied mode and the outdoor temperature drops below
the setback limit, it will switch back into the Occupied mode.
With Early Start feature
Early Start DIP switch = off
Boiler
Power
Steam
established
Heating
cycle
UnOcc.
Auxiliary
WWSD
Early Start
Warning
Boiler
Power
Steam
established
Heating
cycle
UnOcc.
Auxiliary
WWSD
Early Start
Warning
Early Start Condensate Return Sensor
Indoor Sensor S2
Indoor Sensor S1
1 2 3 4
Off
sate Return temperature has not dropped to the "Steam Established" temperature minus the setting of the "Lockout Diff'l (
°F)" dial,
the control will keep the boiler off and leave the "Steam Established" light on, modifying the cycle as illustrated in Figure 9.
UnOccupied Options
Boiler
Power
Steam
established
Heating
cycle
UnOcc.
Auxiliary
WWSD
Early Start
Warning
Establishing Steam
(Warm-up)
Boiler
Power
Steam
established
Heating
cycle
UnOcc.
Auxiliary
WWSD
Early Start
Warning
Boiler
Power
Steam
established
Heating
cycle
UnOcc.
Auxiliary
WWSD
Early Start
Warning
Boiler
Power
Steam
established
Heating
cycle
UnOcc.
Auxiliary
WWSD
Early Start
Warning
Heating Cycle
(on time)
Heating Cycle
(off time)
Lockout
(cool down)