TECH ST-408, User Manual, Page: 5 / 28

Tech
I. Application
ST-408 type thermoregulator is intended for the operation of central
heating system installation. The controller supports two mixing valves
and HUW pump (boiler pump). Optionally, controller may co-operate
with two ST-61 modules, which allows to control four mixing valves
altogether. The controller is equipped with weather control function,
weekly program, and may cooperate with two room two-state
regulators (standard) and with one
TECH regulator.
An additional advantage of the device is the protection of return
temperature , which fulfills the function of protection against boiling of
the water in the short furnace circulation or against too low temperature
of the water returning to the water furnace.
II . Principle of operation
Description of control panel
Operational principle of installation controller is based on mixing the
supplying circulating warm water, with the water, which comes back from
heating circulation, in order to set the desired temperature and maintaining it
all the time at the same level.
The pump is connected to the cycle of each valve, and is supposed to help
water distribution in the system. The pump should be installed behind the
mixing valve, while the temperature sensor should be placed behind the valve
and the pump, for the purpose of the most accurate control of temperature at
valve outlet.
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PRESET
TEMPERATURE
TEMPERATURE
BEHIND VALVE
OPENING
PERCENTAGE
EXIT
PULSE
GENERATOR
STANDBY
MODE
(STANDBY)