tekmar 269 One Stage Steam Control - Manual (Page 4)

Copyright © D 269 - 06/00 4 of 12
Condensate Return Sensor 071 function
Setting a Minimum On Time for a steam system can
become problematic because a system takes more time to
reach operating temperature from a cold start than when it
is hot from a previous cycle. Use of the Condensate Return
Sensor included with the control is highly recommended
since the "Steam Established" dial can then be set to match
the operating characteristics of the system. The control will
turn on its "Boiler" light and fire the boiler for a warm-up
period, modifying the cycle to operate as in Figure 8.
60 minute cycle 60 minute cycle
45 minutes off time 45 minutes off time
15 minutes
on time
15 minutes
on time
Establishing Steam
(W
arm-up period)
Steam established - start cycle
Boiler on
Condensate return
temperature
220
°F
210 °F
200 °F
190 °F
180 °F
170 °F
160 °F
150 °F
140 °F
off
Steam established
temperature setting
on
off
est.
off
on
est.
Boiler Operation
Boiler off Boiler on Boiler off
Steam established - start cycle
Establishing Steam
(W
arm-up period)
Figure 8. 25% on time with Condensate Return Sensor and "Steam Established" dial set to 170
°
F
The control will not start to time out the Heating Cycle until the Condensate Return Sensor reaches the temperature set on the "Steam
Established" dial. When this occurs, the "Steam Established" light will come on and the control will operate the boiler until the on time of the
Heating Cycle has elapsed. This function ensures that steam has been established throughout the system before the Heating Cycle is started.
In a two pipe system, most installers will place the Condensate Sensor on the condensate return line of the radiator furthest from the boiler.
In one pipe systems the best location is usually on the pipe just before it enters the last radiator. These locations are usually good, but in
some larger systems with long runs it may be necessary to place the sensor closer to the boiler so that the first rooms in the system do not
overheat. Again, it is important to ensure that the system components are all working properly, since in a properly vented and drained system,
steam is established quickly throughout the system during each cycle, and sensor placement is not as critical as in some "problem" systems.
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
Condensate return sensor
DIP switch = on
Heating Cycle
(off time)
Heating Cycle
(on time)
60 minute cycle 60 minute cycle
45 minutes off time 45 minutes off time
15 minutes
on time
15 minutes
on time
Steam established - start cycle
Boiler on
Condensate return
temperature
220 °F
210 °F
200 °F
190 °F
180 °F
170 °F
160
°F
150 °F
140 °F
Steam established
temperature setting
off off
on
est.
Boiler off Boiler on Boiler off
Steam established - start cycle
Boiler
Operation
Lockout period Lockout period
on
Establishing Steam
(W
arm-up period)
Establishing Steam
(W
arm-up period)
30 °F Lockout differential setting
Early Start Condensate Return Sensor
Indoor Sensor S2
1 2 3 4
Off
Figure 9. 25% on time with Condensate Return Sensor, "Steam Established" dial set to 170
°
F and "Lockout Diff'l" set to 30
°
F