- Data Brochure D 157 06/10 Difference Setpoint Control 157 The Difference Setpoint Control 157 is designed to operate a variable speed pump to transfer heat from a heat source to a storage tank. Varying the speed of the pump provides fast and accurate temperature control to maintain the target temperature difference (ΔT). Additional minimum and maximum setpoints turn off the pump when heat transfer is no longer desirable.
How to Use the Data Brochure This brochure is organized into three main sections. They are: 1) Sequence of Operation, 2) Installation, and 3) Control Settings The Control Settings section of this brochure describes the various items that are adjusted and displayed by the control. The control functions of each adjustable item are described in the Sequence of Operation. Table of Contents User Interface ............................................................... 2 Display ................................
Display Menu Field Displays the current menu Number Field Displays the current value of the selected item Item Field Displays the current item selected. Status Field Displays the current status of the relay. Buttons Selects Menus, Items and adjusts settings Item Symbol Description Delta T Displays the temperature difference between the source and storage sensors. STORAGE Storage Displays the temperature at the storage sensor. SOURCE Source Displays the temperature at the source sensor.
Sequence of Operation Section A – General Powering Up The Control Source Sensor When the Difference Setpoint Control 157 is powered up, all segments are displayed in the LCD for 2 seconds, and then the type number is displayed for 2 seconds. Next, the software version is displayed for 2 seconds. Finally, the control enters into the normal operating mode and by default the LCD displays the current ΔT temperature.
Mode 3 Heat Dump is for applications where an Mode 4 Booster Pump is for drain back applications alternative heat sink can be utilized when the storage tank and collector are both above their maximum target. The variable speed pump turns off when the tank exceeds its max setpoint. The heat dump pump turns on when both the tank and collectors exceed their max setpoints.
MAXIMUM STORAGE TARGET ΔT TARGET If the storage temperature rises above the maximum storage target, the variable speed pump is turned off. This protects the tank from overheating by stopping the transfer of heat from the collectors. The pump remains off until the storage temperature falls below the maximum storage target less differential. The ΔT target is the turn on point for the variable speed pump.
MINIMUM OUTPUT, % This item selects the minimum speed the variable speed pump will run in order to avoid unwanted drain back when the pump is running at low speeds in a drain back system. At low speeds, some pumps stall and provide no flow. It is important to set the minimum pump speed above this stall point. This setting is adjustable between 0% and 100%. At 100% output the variable speed pump operates as an on/off pump.
Installation Caution Improper installation and operation of this control could result in damage to the equipment and possibly even personal injury. It is your responsibility to ensure that this control is safely installed according to all applicable codes and standards. This electronic control is not intended for use as a primary limit control. Other controls that are intended and certified as safety limits must be placed into the control circuit.
Test the Power Supply Test the Outputs Make sure exposed wires and bare terminals are not in contact with other wires or grounded surfaces. Turn on the power and measure the voltage across the 24 V (ac) power supply with an AC voltmeter. The reading should be between 20 and 28 V (ac). Variable Speed and Second Pump Connect the power supply L and N directly to each pump and use the panel breaker switch to test for 100% output.
Sensor and Un-powered Input Connections Do not apply power 1 2 3 4 Com Src Stor Aux S o Do not apply power to these terminals as this will damage the control. la r C o e ll c t o r Source Sensor Connect the two wires from the Source Sensor 085 to the Com and Src terminals (1 and 2). The Source Sensor is used by the 157 to measure the solar collector temperature.
Display Menus View Menu (1 of 2) View Next Item The View menu items display current operating temperatures and system status information. Use the Item button to view items in this menu. Item Item Field Range Description -99 to 300°F DELTA T Current temperature difference between the source and storage sensors.
View Menu (2 of 2) Item Field Range Description AUXILIARY MINIMUM Minimum auxiliary temperature since this item was last cleared. To clear, press and hold the up and down buttons for 1 second. Note: this item is only available if the auxiliary sensor is connected to the control. -30 to 300°F VIEW MENU (-34 to 149°C) PUMP SPEED Current % output of the variable speed pump.
Adjust Menu (2 of 3) ADJUST MENU Item Field Range Description Actual Setting 2 to 45°F (1 to 25°C) Default = 10°F (5.5°C) MAXIMUM STORAGE DIFFERENTIAL The variable speed pump will turn back on when the storage temperature falls this differential below the Max Storage Target. 70 to 190°F (21 to 88°C) Default = 140°F (60°C) MINIMUM STORAGE TARGET (Mode 2) The supplemental heat pump, P2, will turn on when the storage temperature falls below this target. Optional Auxiliary Sensor.
Adjust Menu (3 of 3) Item Field Range ADJUST MENU 0% to 100% Default = 0% Description MINIMUM OUTPUT, % Minimum pump speed for the variable speed pump to prevent unwanted drainback at low speeds. At 100% Output, the pump operates as an On/Off pump. OFF, 0:10 to 10:00 minutes Default = 3:00 Min MAXIMUM OUTPUT, MINUTES Time the variable speed pump operates at 100% output upon startup to fill a drainback system. If in Mode 4, Booster Pump, this is also the time the booster pump will run upon startup.
Error Messages All errors are latching. If the error condition has been repaired, the control will continue to operate normally. The error message can be manually cleared by pressing the item button. EEPROM READ ERROR The control was unable to read a piece of information from its EEPROM. This error can be caused by a noisy power source. The control will load the factory defaults and stop operation until all the settings are verified. To clear, view all items in the ADJUST menu.
Technical Data Difference Setpoint Control 157 Variable Speed Literature Control Packaged weight Dimensions Approvals — — — — — — Ambient conditions — Power supply Var. Pump Pump 2 Demand Sensors included: — — — — — — — D 157, A 157, D 001, D 070, D 085 Microprocessor control; This is not a safety (limit) control 1.5 lb. (670 g) Enclosure C, White PVC Plastic 4-3/4” H x 2-7/8” W x 7/8” D (120 x 74 x 22 mm) CSA C US, CSA 22.
