Revision 8 THERMO TECHNOLOGIES USDT 2001 Differential Controller Installation and User s Guide
USDT 2001 DIFFERENTIAL CONTROLLER Installation and User s Guide Table of Contents Introduction General Information 1 Installation 3 Collector Sensor 4 Tank Sensor 4 Control Box 6 Power Connection 7 Sensor Connection 7 Operation Control Mode 8 Advanced Mode 9 Diagnostics 10 Characteristics Curves of Sensors 11 5560 Sterrett Place Suite 115 Phone 410.997.0778 Fax 410.997.0779 e-mail info@thermotechs.com June, 2003
USDT 2001 INTRODUCTION 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. reserves the right to change specifications without prior notice. T he USDT 2001 unit is designed to control a simple solar water heating system. By using microprocessor technology it ensures that the collected energy from the sun is transferred efficiently and harnessed under optimum conditions. It monitors collector temperature (T C ) and return temperature (T T, bottom of the storage tank). The solar loop circulation pump runs while the collector temperature exceeds the return temperature by a programmable temperature difference?t. To avoid overheating, the circulation pump stops if the tank (T T ) 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 override?t and can be modified in advanced operation mode to avoid pump cycling. The control unit has the following functions: 2 inputs for temperature sensors Suitable for sensors of type Thermistor and PT1000 All hysteresises are adjustable and depend on temperature Adjustable (0 o F - 50 o F) frost protection Adjustable (32 o F - 200 o F) overheating protection Adjustable (1 o F 50 o F) temperature difference?t Manual override of pump for system testing Digital display of collector, tank,?t, and maximum tank temperature Indications of current state of pump Surge protection at collector sensor 1
USDT 2001 INSTALLATION General Information: USDT 2001 is suitable for Closed and Open Loop systems. Closed Loop Solar Heating Systems are the preferred option for extremely cold areas and areas with questionable water quality. Following arrangement shows an application example in a closed loop system. 1. Collector 7. Check Valve 13. Pressure Gauge 2. Collector Sensor 8. Hose Bibs for Filling and Flushing 14. Collector Supply 3. Manual Air Valve 9. Expansion Tank 15. Heat Exchange Coil 4. Hot Water to Taps 10. Air Purge and Air Vent 16. Solar Hot Water Tank 5. Tempering Valve 11. Circulating Pump with flanges or couplings 17. Immersion Heater 6. Collector Return 12. Pressure Relief Valve 18. USDT 2001 Controller Operation: USDT Controller (18) will switch on the pump (11) when the temperature at the collector sensor T C is higher than the return temperature T R by at least the pre-selected amount?t. The pump circulates a heat transfer fluid around the loop. Heat from the collector is transferred to the storage tank through the heat exchange coil. With the pump running, if?t is less than preset value, the pump will switch off. When a preset tank temperature is reached at T MAX, the controller can switch off the pump. The check valve (non-return valve) prevents heat from the tank rising towards the collector should the tank be warmer (e.g. at night). 2
USDT 2001 INSTALLATION 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 is ready for controlled operation. T he following safety precautions are strongly recommended: 1. Before attempting to install and operate the unit read this instruction manual carefully. 2. Suitably qualified personnel should only 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. 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 (115-volt model) 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 made 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. 5. Do not exceed unit ratings of 2.15 amps (1/6 HP or 245 Watts pump). 6. It is advisable to route power cables away from sensor cables. 3
USDT 2001 INSTALLATION S ensor installation: For the system to function correctly, it is very important that sensors are located and installed properly. Make absolutely sure that they are completely pushed into the optional sensor pockets (not supplied). Sensors must be well insulated in order to prevent them from being influenced by the ambient temperature. When 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. condensation) as this can diffuse through the cast resin and damage the sensor. 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 are corrosion-resistant. Collector sensor (red cable): Either push into a sensor well (sensor pocket) which is soldered or riveted directly to the manifold (vacuum tubes) or absorber (flat plat collectors) that projects from the collector housing, or place a T-piece on the collector return outlet of the outer collector, insert an immersion sleeve (sensor well) into this together with cable connection cover (for moisture protection) and push into the sensor. For vacuum tube collectors, use of PT1000 sensors (480 F max. temperature) is recommended. Hot water tank sensor (white cable): In the case of external heat exchangers, the tank sensor should be installed with an immersion sleeve in 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 outlet so that the immersion sleeve goes into the exchanger tube. Clip-on installation: 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 well in order to measure pipe temperature accurately and to prevent any influence from ambient temperature. Storage tank installation: The sensor required for the solar water heating system is installed in the lower part of the storage tank. As a reference sensor for heating hydraulics, it is advisable to push the sensor beneath the insulation - keeping close to the inner tank wall. 4
USDT 2001 INSTALLATION 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 by means of clips or adhesive tape, using appropriate thermal insulation against environmental influences. Sensor cables can be extended up to 150 ft. A connection between sensor and extension can be established as follows: Cut 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. Then splice wire and slide tubing over splice. Heat gently all around until tubing shrinks tight. Slide larger tubing (about 3/4 ) over the entire completed splice. Heat gently all around until tubing shrinks tight. This connection can then be drawn easily into the pipe work. Caution: Do not overheat tubing! Remove heat as soon as 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. Sensor extension cable: Use 22/4 AWG telephone cable to extend collector sensor from collector to control unit. You need only two wires for sensor cable and the other two wires is considered as spare wires. 5
USDT 2001 INSTALLATION C 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 the device. 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. Undo the four screws at corners of the housing. The control electronics are mounted on the enclosure cover. Using proper fixing, the controller enclosure can be screwed to the wall with cable entry grommets downwards. 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. 6
USDT 2001 INSTALLATION P ower Connections and Wiring Diagram 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 (gauge/conductor) simplify connection to the terminals. All connections should be secure and adequately tightened, as loose power connections will over-heat, and may cause fire. It is important that the specified output loads (245 Watts) are not exceeded. Where these loads expect to exceed, external relays must be used. It is good practice to install a 3 amps in-line fuse to protect controller and pump. Always keep power cables away from sensor cables and other low voltage signal cables. NOTE 3: To protect against lightning damage, the system must be grounded according local regulation. Sensor failures due to the weather or electrostatic are mostly due to poor grounding. NOTE 4: If step-down transformer is not mounted on the circuit board, the unit should be powered by a 24 VDC. A step-down transformer can be used also instead of DC power source, however, the open circuit voltage of AC source must be below 24 VAC. T C terminal should be connected to the Collector Sensor; T T should be connected to the Tank Sensor. The middle terminal is shared between both sensors. NOTE 5: The power supply is 115 V if step-down transformer is mounted on the circuit board. A load of maximum 3 A should be connected to the load terminals (pump) as shown in both above diagram and circuit board. 7
USDT 2001 OPERATION OPERATION Y our controller displays requested information one at a time. Selection indicator and its value blinks interchanged on unit s display window. Push selection key (yellow) once to move to the next selection. Change set value by pressing the Set-Up (blue) key. NOTE: Holding selection key for two seconds brings the controller in advance programming mode. Collector temperature display Tank temperature display Press Set-Up key to increase? T Factory Setting 9.0 o F Range 1 o F to 50 o F (Set Hysteresis value H1X, in advance mode, to H11 for smaller?t values) Press Set-Up key for pump operation mode Aut Automatic Mode On Pump manually actvated OFF Pump manually in off position Press Set-Up key to increase tank over heating protection temperature. Pump stops when tank temperature exceeds this value. Factory setting 160 o F Range 32 o F to 200 o F 8
USDT 2001 OPERATION ADVANCED MODE S etting mode Press the selection key (yellow) for approximately two seconds to switch into the programming/setting mode. Software for solar water heating systems is stored in file P0. P1, P2, and P3 are program files for other applications. This manual covers only the solar water-heating program. Advancing Press the selection key briefly to advance from one setting value to the next. Changing Press Set-Up key once to increase the value. Hold it down to roll back to the lowest value after reaching the maximum value. Normal mode To return to normal operating mode, press the selection key for two seconds while displaying P0. The system also returns to normal mode within one minute if no key is pressed. Software version number sequence Hysteresis curve for temperature differential control. H1x is for temperature difference and H2x is for maximum tank temperature curves with x as a corresponding value. Hysteresis curves (a lagging in the set-point) are variable and are a function of temperature. For example H14 (actual factory setting) means that the hysteresis of the maximum temperature is 4 o F at 64 o F (pump is on at 60 o F and off at 64 o F) or 8 o F at 128 o F. 9
USDT 2001 OPERATION Hysteresis curves for tank temperature. Collector sensor selector - P refers to P1000 sensor Tank sensor selector H refers to thermistor sensor Frost protection display. This value can be set from 0 to 50 Fahrenheit. The factory setting is 0 Fahrenheit. Zero (0) disables the frost protection. Important: It is possible to change the software and its setting in advanced mode. All above values have been set in the factory. They generally do not have to be changed. Unauthorized changes may damage the properties of the control system entirely. Only experts should operate the unit in advanced mode. DIAGNOSTICS: Sensor failure; connection to sensor is lose. Open circuit conditions or wrong sensor attached. Sensor failure; sensor is short-circuited. 10
USDT 2001 Sensor Resistance vs. Temperature Table Temperature Tank Sensor PT 1000 Temperature Tank Sensor PT 1000 [C] [Ohm] [Ohm] [F] [Ohm] [Ohm] 0 1630 1000 32 1630 1000 10 1772 1039 50 1772 1039 20 1922 1078 68 1922 1078 25 2000 1097 77 2000 1097 30 2080 1118 86 2080 1118 40 2245 1155 104 2245 1155 50 2417 1194 122 2417 1194 60 2597 1232 140 2597 1232 70 2785 1271 158 2785 1271 80 2980 1309 176 2980 1309 90 3182 1347 194 3182 1347 100 3392 1385 212 3392 1385 11