2
Introduction
Note: The information supplied in this manual is for guidance only - no part of
this may be used for any agreement, whether express or implied, or to form any
contract. Thermo Technologies reserves the right to change specifications
without prior notice.
he USDT 2004 unit is a powerful temperature differential controller. It can
be used in a wide range of applications. At the factory, it is set to control
a simple solar water heating system. In this program mode,
PROGRAM 0
,
USDT2004 ensures that the collected energy from the sun is transferred
efficiently, and harnessed under optimum conditions. It monitors the collector
temperature (T
1
) and the return temperature (T
2
, bottom of the storage tank). The
solar loop circulation pump runs while the collector temperature exceeds the
return temperature by a programmable temperature difference DELTA T. To
avoid overheating, the circulation pump stops if the collector (T
1
) temperature
reaches the programmable high limit (T
MAX
) temperature. To prevent freezing, the
controller activates the pump and circulates water through the solar loop when
frost conditions exist. The temperature hysteresis (a lagging in the set-point) may
over-ride DELTA T and can be modified in advanced operation mode to avoid
pump cycling. You may measure the temperature of the storage tank (T
3
, top of
the tank) using the third sensor in the program mode 1,
PROGRAM 1
.
The control unit has the following functions
:
•
2 inputs for temperature sensors
•
1 input for flow rate measurement or additional temperature sensor
•
Can be used as BTU meter for constant flow rate or in concert with a flow
meter
•
Suitable for sensors of type Thermistor and PT1000
•
All hysteresises are adjustable and depend on temperature
•
Adjustable (-3
o
F to 41
o
F) frost protection
•
Adjustable (200
o
F to 299
o
F) overheating protection
•
Adjustable (4.1
o
F to 99
o
F) temperature difference DELTA T
•
Manual override of pump for system testing
•
Digital display of all parameters
•
Indications of current state of pump
•
System status and diagnostic displays
•
Collector sensor surge protection
T
