tekmar 423 Universal Reset Module - Manual (Page 25)

25 of 36 © 2007 D 423 - 08/07
Floating Action
The control pulses the actuator motor open or close to
maintain the correct supply water temperature at the mix
supply sensor when there is a requirement for mixing.
The mixing valve that the actuator is connected to can be
either a 2-way, 3-way or 4-way valve. A visual indication
as to whether the control is currently opening or closing
the mixing valve is displayed in the LCD with the words
OPN and CLS while viewing the Mix Supply or Mix Target
temperatures.
Mix Minimum
A Mix Minimum temperature is set for each mixed water
temperature. The Mix Minimum settings are the lowest
temperature that the control is allowed to use as a mix
target temperature. During mild conditions, if the control
calculates a mix target temperature that is below the mix
minimum setting, the mix target temperature is adjusted
to match the mix minimum setting. During this condition,
if the mixing supply temperature is near the mix minimum
setting, the Min segment turns on in the LCD when either
the mix target temperature or the mix supply temperature
is being viewed.
•
• Locate the Mix 1, Mix 2 and the Mix 3 Minimum settings
in the Adjust Menu.
Mix Maximum
A Mix Maximum temperature is set for each mixed water
temperature. The Mix Maximum settings are the highest
water temperature that the control is allowed to use as a
mix target temperature. If the control does target the mix
maximum setting, and the mix supply temperature is near
the mix maximum temperature, the Max segment turns on
in the LCD when either the mix target temperature or the
mix supply temperature is viewed.
•
• Locate the Mix 1, Mix 2 and the Mix 3 Maximum settings
in the Adjust Menu.
Boiler Minimum Protection
The control is capable of providing boiler protection from
cold mixing system return water temperatures. If the boiler
water temperature is cooler than the Boiler Minimum
setting while the boiler is firing, the control reduces the
output from the mixing devices. The mixing outputs are
reduced at the same rate. Reducing the mixing output
limits the amount of cool return water to the boiler and
allows the boiler water temperature to recover. This feature
can only be used if the boiler sensor is on the supply or
on the return but is not available when the boiler sensor
is not present.
Domestic Hot Water Temperature Operation Section H
DHW Demand
Powered DHW Demand
A powered DHW Demand may be used to provide heat to
the DHW system. A DHW aquastat or setpoint control is
used as a switch in the DHW Demand circuit. The control
registers a DHW Demand when a voltage between 24 and
230 V (ac) is applied across the DHW Demand terminals
(75 and 76).
•
• The Off / DHW Sensor DIP must be set to Off.
DHW Sensor
A DHW Sensor may be used to provide heat to the DHW
system. A DHW Sensor must be connected to the DHW
Sensor terminals (66 and 67). Once the DHW sensor drops
1/2 of the DHW differential setting below the DHW setting,
the control registers a DHW Demand.
• • The Off / DHW Sensor DIP must be set to DHW Sensor.
Once the control detects a DHW Demand, the DHW Demand
segment turns on in the LCD.
DHW Differential
When using a DHW Sensor, a DHW Demand is registered
when the DHW sensor drops 1/2 of the DHW Differential
setting below the DHW setting. The DHW Demand is satisfied
once the DHW Sensor rises 1/2 of the DHW Differential
setting above the DHW setting.
•
• Locate the DHW Differential setting in the Adjust
Menu.
Boiler Target Temperature
The boiler target temperature is at least as hot as the DHW
Exchange setting (when using a Powered DHW Demand)
or at least as hot as the DHW setting plus 40°F (22°C)
(when using a DHW Sensor). The DHW Demand overrides
the boiler reset target temperature, except when the boiler
reset target is higher than the DHW target.
•
• Locate the DHW Exchange setting in the Adjust
Menu.