Thermo Technologies USDT 3000 User Manual

Revision

1

Note:

The information supplied in this manual is for guidance only

-

no part of this may be

THERMO TECHNOLOGIES

USDT 3000 Advanced 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:

• 3 inputs for temperature sensors

• Suitable for type PT1000 sensors

• Auxiliary relay for overheating protection and supplement heating system

• Adjustable (2

• Manual override of pump for system testing

• Symbolic display of all parameters

• Concurrent display of two temperatures

• Indications of current state of pump

• System status and diagnostic displays

o

C to 19 o C) temperature difference (delta T)

 Thermo Technologies

5560 Sterrett Place • Suite 115

Phone [phone] • Fax [phone]

e-Mail [e-mail]

July, 2004

Installation and User’s Guide

1

Introduction

he USDT 3000 unit is a multifunctional temperature differential controller. It can be used

in a wide range of applications. At the factory, it is set to control a standard solar water
heating system with an auxiliary relay to divert surplus heat. The auxiliary relay can be used to
maintain the tank temperature. It can protect the system from overheating or using another heat
source to heat the storage tank. The controller has inputs for three PT1000-sensors. A 3-key­panel below a large LCD serves as the user interface. Simple icons give information about the
function and operational mode of the controller and the system performance.

Principle of Operation – In the simplest form the solar system needs two sensors. One is

positioned at the collector, S1, to monitor the collector temperature (TC). The second is positioned
at the location S2 such that it measures the temperature of
the heat transfer fluid inflowing into the collector. (TS,
bottom of the storage tank after the storage tank extracts
the heat from the collector.) As the sun shines on the
collector, the collector sensor picks up the temperature rise
while the return sensor (TS) remains at the existing
temperature. The difference between these two
temperatures is referred to as delta T. The solar pump A1
runs while delta T exceeds the adjustable temperature
difference. To avoid overheating, the Auxiliary relay (R2)
can be used to divert the surplus energy if the tank sensor
S3 reaches its set point.

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 delta
T. The pump stops if delta T is less than the preset value:

A1 (ON) only for S1 > (S2 + Delta T)

S1

A1

S3

S2

The third sensor can be used for temperature monitoring of the tank and activation of R2 relay as
the above example shows. Its function is totally independent from controller operation condition.

2

T

S

INSTALLATION

Note: This installation procedure is for guidance only, and the installer should verify its
suitability. Make sure that the solar/boiler system is physically installed, manually tested, and is
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 any maintenance required.

3. It is recommended that the unit be connected to the power supply via a suitably 6 amps

isolating switch.

4. The unit is designed for indoor use only. It is not suitable for installation in hazardous

locations and should be protected from electromagnetic field.

5. WARNING: When the unit is connected to the 115 -volt power supply and the cover is

opened, high voltage circuits will be exposed. Therefore, when installing the unit ensure
all required connections are made and the cover is attached to the controller box before
turning the power on. Ensure that all the connections are secure. If any maintenance work is
required ensure that the unit is isolated 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.

6. Do not exceed unit ratings of 2.15 amps (1/6 HP or 245 Watts pump).

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

ensor installation: Temperature sensors may be installed in fluid lines by inserting it

into a sensor pocket or strapping it directly to the pipe. For the system to function
correctly, it is very important that the sensors are located and installed properly. The collector
sensor should be installed at the upper part (collector outlet) of the collector. If you are using a
sensor pocket, make absolutely sure that the sensors are pushed completely into the sensor
pockets. (Sensor pockets are not supplied.) Sensors must be well insulated in order to prevent
them from being influenced by the surrounding temperature.

When sensors are used outdoors, no water should be allowed to get into the immersion sleeves
(lasting impedance change). Generally, sensors should not be exposed to moisture (e.g.

3

condensation) as this can diffuse through the cast resin and damage the sensor. If exposed to
moisture, heating at approx. 195 °F for one hour may possibly save the sensor.

When sensors are used in open loops or swimming pools, make absolutely sure that immersion
sleeves (sensor pockets) are corrosion -resistant.

l Collector sensor FKP6 (Black Cable, Five Feet): The cable of the collector sensor is

silicone coated and is temperature and weather resistant. Insert the sensor sleeve into a thermo­well (sensor pocket), or strap it to the collector outlet pipe that projects from the collector housing.
The best practice to house the collector sensor is to install a suitable sensor pocket into a T-piece
on the collector outlet pipe. It is good practice to shield the sensor cable and its extension from
UV rays and moisture.

l Hot water return sensor FRP6 (Gray Cable, Nine Feet): The return (collector inlet) sensor

should be installed with an immersion thermo-well in the return leg (cold side) of the heat
exchanger. If there is no provision for a tank sensor, it is advisable to push the sensor sleeve
beneath the insulation – keeping it close to the inner tank wall at the desired tank location. The
sensor required for the solar loop “cold” leg is installed usually in the lowest part of the storage
tank.

l Clip-on installation: The Sensor is best secured to the appropriate line with pipe clamps,

clips, etc. whereby you must make sure that the material is suitable (non -corrosive, heat-proof,
etc.). It is advisable to insulate the sensor in order to measure the pipe temperature accurately
and to prevent any influence from surrounding temperature.

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). Another possibility would be to attach the sensor at the same place with clips or
adhesive tape, using appropriate thermal insulation against environmental influences.

l Sensor cable extension: Sensor cables (22/4 AWG telephone cable) can be extended up

to 150 ft.

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

positioned at eye level. It is always good practice to keep
electronic equipment away from cold and heat, as extremes
of temperature may reduce the lifetime of these devices. It is
also good practice to keep electronic equipment away from
heavy electrical loads, switches or contactors as these may
cause electrical and electromagnetic interference when
switched on or off.

1. Unscrew the cross-recessed screw off the cover and
remove it from the housing.

2. Mark the upper fastening point on the wall and install
the enclosed dowel and screw it in.

3. Hang up the housing at the upper fastening point and
secure the base unit using the lower fastening hole.

4

Wire Connection: A small blade screwdriver may be used to fas ten miniaturized terminal block
screws while the corresponding wire is inserted.

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 a screw that provides
excellent contact without damage to the wire.

Use up to an 18 AWG stranded wire to connect the sensor cables to the unit.

• S1 collector sensor (higher temperature) 1 & 2

• S2 return sensor (lower temperature) 3 & 4

• S3 tank sensor (additional measure point) 5 & 6

• Ground terminals 12, 13, 14

• Relay R2, auxiliary relay for heat extraction

R2 live line (Black) 16
N neutral conductor (White) 15
Ground clamp (Green) 14

• Relay R1, solar loop pump
R1 live line (Black) 18
N neutral conductor (White) 17
Ground clamp (Green) 13

• Power Supply, 120 V AC
L live line (Black) 20
N neutral conductor (White) 19
Ground clamp (Green) 12

5

P

ower Connections: A small blade screwdriver may be used to fasten miniaturized
terminal block screws while the corresponding wire is inserted.

NOTE 1: Always disconnect the controller from power supply before opening the housing.
NOTE 2: The controller should be properly grounded. Flexible wires, 18/3 AWG

(gauge/conductor), simplify connection to the terminals. The power terminal block will
accommodate wire sizes to 14 AWG. All other connections should be secured and adequately
tightened, as loose power connections will over-heat, and may cause fire.

NOTE 3: It is important that the specified output loads (245 Watts) are not exceeded. Where
these loads expect to exceed, external relays must be used. Always keep power cables away
from sensor cables and other low voltage signal cables.

NOTE 4: To protect against lightning damage, the system must be grounded according to local
regulations. Sensor failures due to the weather or electrostatic are mostly due to poor grounding.

6

A

OPERATION

djustment keys: The USDT 3000 user interface is accessible via the three

pushbuttons. The forward key (1) is used for scrolling forward through the indication
menu or to increase the adjustment values. The backwards key (2) is accordingly used for the
reverse function.

To enter the parameter adjustment mode hold the forward key for 2 sec while HO is displayed.
The “SEt” icon will be displayed on upper corner of LCD once
you are in the adjustment mode. Now, you can select the
parameter you wish to adjust by using the forward and
backwards keys. Press the key “SEt” (3) in order to change the
selected parameter:

• Select a parameter by keys 1 and 2

• Shortly press key 3, so that “SEt” flashes

• Adjust the value by keys 1 and 2

• Press key 3, so that “SEt” permanently appears, the adjusted value is now saved

Please note: The circulation pump (A1) stops at tank temperature of 90 °C to avoid tank
overheating.

Parameter List

TC Collector temperature
TS Tank (return) temperature
TT Thermostat temperature (control temperature for R2 relay)
HO Solar operating hours (to be used for energy calculation)
DO Pump starting temperature difference
DF Pump switch off temperature difference
SX Maximum tank temperature
CL Collector limiting temperature
CX Maximum collector temperature
CN Minimum collector temperature
TO Thermostat (R2) switch on temperature
TF Thermostat (R2) switch off temperature
FN Function:

0 : Maximum tank temperature disable
1 : Maximum tank temperature enable
2 : Maximum tank temperature disable, cooling function enable
3 : Maximum tank temperature enable, cooling function enable
MM Manual operation mode:
0 : relays R1 and R2 are deactivated
1 : relay R1 is activated, relay R2 is deactivated
2 : relay R1 is deactivated, relay R2 is activated
3 : relays R1 and R2 are activated
4 : automatic operation

PG Program number
VN Version number

7

The pump A1 stops

when the tank temperature reaches its set point (SX). The

system will stagnate. When the collector exceeds its maximum

(CX), the operating control lamp flashes

green and the solar pump A1 (R1) comes on to “cool” the

system. The tank temperature might increase above (SX), but

only up to 90 °C (safety shutdown of the tank). This function

or very hot summer days

mal relief for the collectors and the system.

The factory setting is 120 °C (shown in display), but it can be

mum

collector temperature is a minimum switching temperature. It

must be exceeded to turn the solar pump A1 (R1) on. The

minimum temperature reduces pump cycling at low solar

Examples

Delta T Adjustment -The controller monitors temperatures at

S1 and S2 locations and compares the resulting temperature
difference with delta T. The solar loop circulation pump (A1)
runs, when the measured temperature difference delta T is
higher than or identical to the set value (DO). The pump stops
at the shut off temperature (DF). The Following parameters are
factory defaults:

DO 6 °C and DF 4 °C

Maximum Tank Temperature (SX) - The solar pump A1 stops
(R1) to avoid tank overheating (safety shutdown of the tank) at
this (SX) set point. The overheating symbol flashes if the
maximum tank temperature is exceeded. The factory setting is
(see FN =3) 60 °C. To disable this protective feature of the
unit, change FN to 0.

Solar Loop Limiting Temperature - If the temperature of the
solar loop exceeds the set point temperat ure (CL), the solar
pump A1 stops (R1) in order to protect the solar components
from overheating (collector safety shutdown). The factory limit
temperature is set to 140 °C but it can be changed within the
adjustment range of 110-200 °C. The operating control lamp

flashes red if the temperature limit is exceeded.

Maximum Collector Temperature (CX) –

design temperature

guarantees a longer operating time f
and ensures a ther

changed within the adjustment range of 100 -190 °C.
Minimum Collector Temperature (CN) - The mini

radiation times such as early morning.

8

s this feature. User can

While the tank temperature is higher

mp runs until the tank temperature drops

below the maximum tank temperature (SX). This feature avoids

mature temperature safety valve operation.

It can happen only if hot water consumption is below the system

When the maximum tank

temperature (SX) is reached, the solar pump A1 (R1) stops. The

collector temperature now rises to the maximum collector

ump starts

again to extract heat from the collector. The tank temperature

but only up to 90 °C (system overheating

safety shutdown). The solar pump stops if the tank temperature

ture

if the collector temperature is at least 5K below the tank

The USDT 3000 is equipped with

a 2nd relay (R2) and a 3rd temperature sensor input (S3, e.g.

sed for the

tank temperature monitoring and safeguarding. It works

independently from the solar operation. The relay (R2)

on temperature (TO) and

off temperature (TF). They must be programmed in the

windows. For example, it can be used to divert

the collected energy to another user after reaching the desired

tank temperature. TO and TF are disabled by setting them to 40

TO = TF (R2) relay is energized only if the maximum

The factory setting is 10 °C that disable
change this set point from –10 to + 90:

• Use –10.0 to 9.9 for frost protection in sunbelt regions

• Use 10.1 to 90 to permit start -up operation

Heat Extraction (FN 2) –
than (SX), the solar pu

overheating and pre ­capacity such as holidays or low hot water usage.

Collector Cooling Function (FN 3) -

temperature (CX). At this temperature the solar p
may increase (SX) ­approaches 90 °C. It runs again to reduce the tank tempera
temperature.

Thermostat Function (TT) –
TT measures the upper tank temperature). It can be u

operations are programmed by switch­switch­corresponding

°C at the factory:

•

tank temperature is reached

• TO > TF to be used to divert the surplus heat

• TO < TF to be used with an auxiliary heating system

9

T

S

ROUBLESHOOTING
Problem: Nothing happens when unit is powered -up.

Cause/Remedy: The fuse could be blown – check and replace if necessary. If the fuse blows

again, then the pump draws more current than the unit is design to supply. Use an auxiliary relay
or contact your product supplier.

Problem: Operating control red lamp is flashing.
Cause/Remedy: This indicates a system alarm warning, which may be caused by a sensor fault:

• Error code –888.8 is displayed è (TC, TS or TT) sensor cable is short circuited

• Error code 888.8 is displayed è (TC, TS or TT) sensor cable is open

Following table shows the impedance characteristics of PT 100 0 sensors:

o

C - 10 0 10 20 30 40 50 60 70 80 90 100 110

o

F 14 32 50 68 86 104 122 140 158 176 194 212 230

OHM

961 1000 1039 1078 1117 1155 1194 1232 1271 1309 1347 1385 1423

PECIFICATION

Supply Voltage 120 V AC
Fuse 4 A
Phantom Load max. 2 W
Hysteresis 6 degrees
Delta T 4 – 24 oF
Overheating Range 100 – 200 oF