Thermo Technologies USDT 2005 User Manual

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3

Note:

The information supplied in this manual is for guidance only

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no part of this may be

THERMO TECHNOLOGIES

USDT 2005 Analog Differential Controller

used for any agreement, whether express or implied, or to form any contract. Thermo
Technologies reserves the right to change specifications without prior notice.

The control unit has the following functions:

• 2 inputs for temperature sensors

• Suitable for sensors of type Thermistor and PT1000

• Adjustable (70 o F to 210 o F) overheating protection

• Adjustable (4

• Manual override of pump for system testing

• Symbolic display of all parameters

• Indications of current state of pump

• System status and diagnostic displays

• Collector sensor surge protection

o

F to 24 o F) temperatu re difference delta T

 Thermo Technologies

5560 Sterrett Place • Suite 115

Columbia, Maryland 21044

Phone [phone] • Fax [phone]

e-Mail [e-mail]

May, 2005

Installation and User’s Guide

1

S2 A1

A1 S1

Introduction

he USDT 2005 unit is an analog 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.

Solar System Control (S) Mode

In this program mode, it ensures that the collected energy from the sun is transferred efficiently,
and harnessed under optimum conditions. It monitors the collector temperature (TKS) and the
return temperature (TBS, bottom of the storage tank). The
solar loop circulation pump runs while the collector
temperature exceeds the return temperature by an
adjustable temperature difference ?T. To avoid
overheating, the circulation pump stops if the return
temperature (TBS) reaches the adjustable high limit (T
temperature. The temperature hysteresis (a lagging in the
set-point) may over -ride ?T to avoid pump cycling.

The pump A1 runs only when the temperature at the
collector sensor location S1 is higher than the return
temperature at location S2 by at least ?T. The pump stops
if ?T is less than the preset value or, the if the temperature
at location S2 (storage tank) has reached the T

MAX

Boiler Control (L) Mode

The User can switch USDT 2005 to operate a boiler circulator. In boiler mode (L), the pump runs
only when boiler temperature at S1 location
is higher than the minimum set point dialer
and the ?T condition is satisfied.

A1 (ON) only when S1 > max &

S1 > (S2 + diff)

Note: The maximum temperature dialer
(max) serves as the minimum starting
temperature, T
must change the switch position on the back
of the circuit board to use the USDT 2005 as a boiler controller. Details will follow.

MAX set point protects the solar system from overheating. It turns off the circulator if the boiler
contribution to the storage tank is not satisfied.

in the boiler mode. User

MIN

)

MAX

A1 (ON) only when S1 > (S2 + diff)
& S2 < max

S1

S2