tekmar 374 Universal Reset Control - Manual (Page 24)

© 2009 D 374 - 03/09 24 of 36
Rotate / Off
The Rotate / Off DIP switch selects whether or not the control is to
provide Equal Run Time Rotation of the boiler stages. If the switch is
set to
Rotate, the stages will be rotated accordingly. If the switch is set
to Off, the firing sequence is fixed starting with Stage 1 then Stage 2.
Floating / Variable
The Floating / Variable DIP switch selects whether the control is to
operate the mixing devices using floating action actuating motors or
variable speed injection pumps.
30% Enable / 10% Enable
The 30% Enable / 10% Enable DIP switch is only active when the
Boiler Sensor Return / Supply DIP switch is set to Return. When set
to
30% Enable, the Boiler Enable terminals (21 and 22) close when
the mixing device reaches 30% operation. When set to 10% Enable,
the Boiler Enable terminals (21 and 22) close when the mixing device
reaches 10% operation.
Boiler Sensor Return / Supply
The Boiler Sensor Return / Supply DIP switch selects the installation
location of the boiler sensor. When the boiler sensor is installed on the
supply side of the boiler loop, the DIP switch must be set to
Supply.
The boiler’s aquastat should be set at least 20°F (11°C) higher than
the required design boiler water temperature.
For systems where the control provides a heat demand to an external boiler control, the boiler sensor should be installed on the
return side of the boiler loop and the
Boiler Sensor Return / Supply DIP switch must be set to Return. The control only enables the
boiler when the output of the mixing device exceeds the 30% Enable / 10% Enable DIP switch setting. The Boiler contact is controlled
as described in section B. The boiler’s operating temperature is controlled by its aquastat, or an external boiler reset control.
Boiler Sensor
Variable
Off
Supply Installer
Advanced
Setback 30% Enable
10% Enable
Return
Floating Rotate
Boiler Sensor
Variable
Off
Supply Installer
Advanced
Setback 30% Enable
10% Enable
Return
Floating Rotate
Boiler Sensor
Variable
Off
Supply Installer
Advanced
Setback 30% Enable
10% Enable
Return
Floating Rotate
Boiler Sensor
Variable
Off
Supply Installer
Advanced
Setback 30% Enable
10% Enable
Return
Floating Rotate