Thermo Products USDT2004 User Manual

USDT 2004

Installation and User’s Guide

Introduction
General Information 2

Installation 3

Collector Sensor 3
Control Box 5
Power Connection 6
Display Window 6

Operation

Basic Operation (Factory Setting for Only Two Sensors) 7
Manual Operation Mode 8
Three Sensor Operation 9
Sensor Selection 11
Alarm Functions and Diagnostics 12
Energy Calculations 13

Troubleshooting 14

 Thermo Technologies

5560 Sterrett Place • Suite 115

Columbia, Maryland 21044

Phone [phone] • Fax [phone]

e-Mail [e-mail]

Revision 7, November 2005

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S2 A1

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.

SDT 2004 is a powerful temperature differential control unit. It has *two programs and
may be used in a wide range of applications:

PROGRAM 0 – This program is USDT 2004's basic program. Set at the factory, it uses two
sensors to control a simple solar water heating system.

PROGRAM 1- This program allows the user to customize USDT 2004 for applications where a
third sensor is required. With this program you may, for example, measure the flow rate or the
temperature of the storage tank (T3, top of the tank).

*USDT 2004 has additional programs available for a wide variety of advanced applications, these programs are not

supported at this time.

The control unit has the following functions:

• 2 inputs for temperature sensors (PROGRAM 0)

• 1 input for flow rate measurement or additional temperature sensor (PROGRAM 1)

• BTU meter capability for constant flow rate or with a flow meter

• Adjustable hysteresises dependant on temperature

• Adjustable (-3

• Adjustable (200 o F to 299 o F) overheating protection

• Adjustable (4.1

• Manual override of pump for system testing

• Digital display of all parameters

• System status and diagnostic displays

Program 0 – Two Sensor Operation (Factory Setting)

Program 0 monitors the collector temperature (T1, at S1) and the return temperature (T2, at S2 ,
bottom of the storage tank). The solar loop circulation pump runs while the collector temperature
exceeds the return temperature by an adjustable
temperature difference diff. To avoid overheating, the
circulation pump stops if the return temperature (T2)
reaches the adjustable high limit (T
temperature hysteresis (a lagging in the set-point) may
over-ride diff 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 diff (?T). The pump
stops if diff is less than the preset value or, when the
temperature at location S2 has reached the T

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

o

F to 41

o

o

F) frost protection

F to 99 o F) temperature difference ?T

) temperature. The

MAX

:

MAX

S1

3

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INSTALLATION

Note: This installation procedure is for guidance only, and the installer should verify its
suitability. Make sure that the solar system is physically installed, manually tested, and ready for
controlled operation.

he following safety precautions are strongly recommended:

1. Before attempting to install and operate the unit read this instruction manual carefully.

2. Only suitably qualified personnel should carry out installation and required maintenance.

3. It is recommended that the unit be connected to the power supply via an isolating switch of 6
amp.

4. WARNING: When the unit is connected to the 115 -volt power supply and the cover is
opened, high voltage circuits will be exposed. When installing the unit, all required
connections should be completed and the cover attached to the controller box before turning
the power on. Ensure that all connections are secure. If any maintenance work is required
isolate the unit from the power supply before removing the cover. Never leave the unit
unattended if the cover has been removed and the power supply is connected.

5. Do not exceed unit ratings of 3.15 amps (1/6 HP or 245 Watts pump).

6. It is advisable to route power cables away from sensor cables.

ensor installation: Temperature sensors may be installed in fluid lines by mounting in a
tee or strapping it to the piping directly. For the system to function correctly, it is essential

that the sensors are located and installed properly. They MUST be pushed completely
into the optional sensor pockets (Thermowell is not supplied). Sensors must be well insulated in
order to prevent them from being influenced by the ambient temperature.

When used outdoors, water must not enter the immersion sleeves (lasting impedance change).
Exposure to moisture (e.g. condensation) can diffuse through the cast resin and damage the
sensor. In this event, heating at approx. 195 °F for one hour may reverse the damage.

When sensors are used in open loops or swimming pools, corrosion-resistant immersion sleeve,
(sensor pockets), must be used.

l Collector sensor (red cable with protective terminal box): Either push into a thermowell,
(sensor pocket), which is soldered or riveted directly to the manifold (vacuum tubes). Alternately,

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strap the sensor to the collector outlet pipe or the absorber (flat plate collectors) that projects from
the collector housing. Ideally, house the collector sensor (encased in a suitable sensor pocket)
into a T-piece on the collector return outlet. Protect the sensor cable from UV and moistur e.

l Return (tank) sensor (white cable): The sensor required for the solar loop return is installed
in the lower part of the storage tank. If there is no provision for this tank sensor, push the sensor
beneath the insulation – keeping it close to the inner tank wall at the desire tank location.

For external heat exchangers, the tank sensor should be installed with an immersion sleeve in the
return leg (cold side) of the heat exchanger. In tanks with integrated heat exchangers, the sensor
pocket should be fitted at the exchanger's return to the collector.

l Pool sensor installation: Place a heat conductive T-piece on the suction line directly at the
pool outlet and screw in the sensor with an immersion sleeve (check corrosion resistance of the
material used). Alternately, attach the sensor with clips or adhesive tape, using the appropriate
thermal insulation to guard against environmental influences.

l Sensor cable extension: Sensor cables (22/4 AWG telephone cable, you need only two
wires of 4) can be extended up to 150 ft. A connection between the sensor and extension can be
established as follows:

Cut the supplied heat-shrinkable tubing to desired length (about ½ ”). Slide tubing over one end of
wire to be sliced (after removing enough outer insulation to accept the tubing). Splice the wire
and slide tubing over the splice. Heat gently all around until tubing shrinks tight.

Slide larger tubing (about ¾ “) over the entire completed splice. Heat gently all around until tubing
shrinks tight. This connection can then be drawn gently into the pipe work. Only two of the wires
are required for the sensor cable; the other two wires are spare wires.

Caution: Do not overheat the tubing! Remove heat as soon as the tubing shrinks tight, as
material will continue to shrink. With flame source, use even back and forth motion all around
tubing. A heat gun may be used, if available. Let tubing cool for maximum strength.

ontroller unit installation: For viewing comfort, the controller unit should be positioned

at eye level. For optimum longevity, avoid extremes of temperature in the placement of
electronic equipment. In addition, avoid heavy electrical loads, switches or contactors as these
may cause electrical and electromagnetic interference with the unit (when switched on or of f).

5

Undo the screw at the top of the housing. The control electronics are mounted on the enclosure
cover. The controller enclosure can be screwed to the wall with cable entry grommets pointed
downwards. Use the supplied plastic bridges to secure power and sensor cables.

Base of the unit to be mounted at eye -level and wired as shown above

Caution: Controller wiring should only be done when the unit is not energized. It is possible to
damage the control unit if it is assembled under voltage. Miniaturized terminal blocks are used for
making wiring connections. The wire is held in place within the terminal with screw that provides
excellent contact without damage to the wire.

Sensor Cable Connection: Use up to an 18 AWG stranded wire to connect the sensor cables to
the unit. The S1 terminal should be connected to the collector sensor (higher temperature); the
S2 terminal is designated for the tank sensor (lower temperature). And the S3 terminal is
reserved for the advanced usage of the unit such as third temperature sensor (in program mode

1) or flow meter input for BTU operation in advanced programming mode.