AC Only Differential Controller

 


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This differential control has a self contained DC power adapter to power the controller. It's mounted inside a double wide AC outlet box and the AC wires and temperature probe extension wires are hidden behind the wall. Both the on and off differential set points are user programmable. In addition there are programmable freeze and boil functions and set points. The user may also set the control to function in either degrees Fahrenheit or Centigrade. The pump control can be set to ON, OFF, or Auto. All functions are set by two buttons and menu items that are displayed on the two-line LCD display. When not setting functions, the LCD displays collector, storage, and differential temperature, as well as a pump ON/OFF indication. This control operates on 115 VAC. The low voltage power supply for the control and sensors is on board, and requires no other power source than the 115 VAC. An output relay for pump control is also integrated onto the control. The entire control is designed to fit into a double receptacle box. A wood wall plate is provided with the control, which mounts the control to the receptacle box. The 115 VAC connections are done with wire nuts to make the supply and pump connections fast and safe. The sensor connections are made via a spring type terminal strip, simple push in connections, no screws.

Pump Control
The pump can be set to be continuous ON, continuous OFF, or AUTO. The ON setting will run the pump continuously. This is used for filling of some systems, or you just want continuous operation of the pump. The OFF setting turns off the pump continuously. This would be for turning off the pump for the summer or other situations when you do not wish the pump to run. The AUTO setting runs the control in normal differential control along with the freeze and boil setting selected.


Differential Set Points
Two set points are available for the differential temperature function, DiffOn and DiffOff. A differential temperature is calculated by subtracting the storage temperature from the collector temperature. The relay output will turn on when the differential is above the DiffOn set point. The relay output will remain on until the differential is below the DiffOff set point. 


Freeze and Boil Limits
The Freeze and Boil set points are user settable via a menu system. The functions that occur at those set points are also user programmable via the menu.
Freeze Limit Choices:


OFF - no freeze protection

ON Below Set Point Pump relay will turn on when collector temperature is below the freeze set point, when collector temperature returns above the freeze set point the control returns to normal differential control. This Limit selection will circulate water through the collector to prevent it from freezing. This is for use in climates that seldom experience freezing conditions, when no anti freeze is in the system.

OFF Below Set Point Pump output will never turn on when collector temperature is below the freeze set point. Use this selection when you do not ever want the pump to run when the collector is below the freeze set point. We recommend that an external separate control and sensor be used for this function for a backup.


Boil Limit Choices:


OFF no boil protection

ON Above Set Point Pump output will turn on when collector temperature is above the boil set point, regardless of the differential temperature between collector and storage. The control will return to normal differential control once the collector temperature is below the boil set point. This mode is for systems that have collectors, or systems that will be damaged when collector temperature exceeds set point. Be sure the entire system will withstand those temperatures. An external heat dump and control is also recommended to remove the excess heat. 

OFF Above Set Point Pump output will turn off when collector temperature is above set point, regardless of the differential temperature between collector and storage. The control will return to normal differential control once the collector temperature is below the boil set point. This choice is for systems that will be damaged when collector return temperature is in excess of the boil set point. For instance when plastic piping or plastic storage containers are use, and will soften or distort with high temperatures. Be certain that the collector will withstand the high stagnation temperatures that will occur. Closed systems will require pressure relief valves to prevent explosions. 

Fahrenheit/Centigrade select:
Either Fahrenheit or centigrade temperature display and control may be selected. When changing from one to the other default set points are use. Be sure to verify that the OnDiff, OffDiff, Boil, and Freeze settings are as desired after changing from one to the other. Old set points are not retained when moving from one to the other HOWEVER all settings are retained in non volatile memory on power failure. Upon restoring power the settings from memory are reinstated. This includes the pump mode, ON, OFF, or AUTO 

User Menu for Programming

Main -displays collector, storage, differential temperature, and pump on/off
Pump Mode -select pump ON, OFF, or AUTO
On Differential -set the On Differential set point
Off Differential -set the Off Differential set point
Freeze Set Point -set the Freeze set point
Freeze Function -choose the function at freeze set point
Boil Set Point -set the Boil set point
Boil Function -choose the function at boil set point
Fahrenheit Centigrade Select -display and control in Fahrenheit or Centigrade scale

When the main menu is being displayed, press the Increment button. One by one the above menu choices are displayed. Release the button when the menu name you wish to access is displayed on the LCD display. Then use either the Increment or Decrement button to change the value displayed for the selected menu item. The Main menu will be redisplayed when no buttons have been pressed for 5 seconds. Once the Main menu is displayed the Increment button can again be used to scroll thru the available menu choices and change additional set points. 

Setting the Pump Mode
Use the menu to display the pump mode. Use the INC or DEC button to change the mode to ON, OFF, or AUTO. The pump mode will remain in the selected mode until changed. After 5 seconds of no button press the display will return to displaying the collector and storage temperatures.

Setting the DiffOn set point
Use the menu to display the OnDiff set point. Use the INC or DEC button change the set point. After 5 seconds of no button press the display will return to displaying the collector and storage temperatures. The DiffOn set point has a minimum setting of 2 and a maximum setting of 40. It also cannot be set lower than the DiffOff set point + 2.


Setting the DiffOff set point
Use the menu to display the OffDiff set point. Use the INC or DEC button change the set point. After 5 seconds of no button press the display will return to displaying the collector and storage temperatures. The OffDiff set point has a minimum setting of 0, and cannot be set higher than DiffOn 2.
Setting the Freeze set point
Use the menu to display the Freeze set point. Use the INC or DEC button change the set point. After 5 seconds of no button press the display will return to displaying the collector and storage temperatures. The Freeze set point has a minimum setting of 0, and a maximum setting of 50.
Setting the Freeze function
Use the menu to display the Freeze function menu item. Use the INC or DEC button change the function. After 5 seconds of no button press the display will return to displaying the collector and storage temperatures. 
Setting the Boil set point
Use the menu to display the Boil set point. Use the INC or DEC button change the set point. After 5 seconds of no button press the display will return to displaying the collector and storage temperatures. The Boil set point has a minimum setting of 90, and a maximum setting of 220.
Setting the Boil function
Use the menu to display the Boil function menu item. Use the INC or DEC button change the function. After 5 seconds of no button press the display will return to displaying the collector and storage temperatures. 
Setting Fahrenheit Centigrade control/display
Use the menu to display the Fahrenheit/Centigrade menu item. Use the INC or DEC button change the scale. After 5 seconds of no button press the display will return to displaying the collector and storage temperatures. Keep in mind that default set points are installed any time the temperature scale is changed. Verify all settings any time the scale is changed.


Sensor lead Colors
Red Lead +5 (Connect to + on sensor terminals)
Green Lead GND (Connect to on sensor terminals)
White Lead Temperature 
(Terminal labeled C on board is collector)
(Terminal labeled S on board is storage) 
115 AC Connections
Three wires are provided to connect the incoming 115 VAC and pump. 
Black Wire Connect to incoming AC line, also usually black
White Connect to incoming Neutral, also usually white, connect neutral lead of pump here also
Red Connect to other pump lead
Use wire nuts to make all connections. Verify no stray stands of wire protruding from the wire nuts. A wrap of electrical tape around the wire nut and wires is recommended.
NOTE: be sure to connect the bare (or green) ground wire to a ground wire continuing to the pump. If the electrical box is metal, connect ground to the box as well. No ground connections to the control are needed.
NOTE: Keep all 115 volt AC wiring in the lower half of the electrical box, to prevent inducing noise into the control and sensor wires. This also means keeping the sensor wires in the top half of the box. Not following this recommendation may result in erratic functioning of the control.
FUSE - 5 AMP, slow blow, 5mm x 20mm, 250vac
Surge Suppressor Provided for protection against line voltage spikes.


This is the wiring for the
AC only B, but the probe connections and the AC connections would be the same for the AC only M. The main difference between the model B (basic) and the model M (monitor) have to do with the use of the monitor and the use of some additional functions. The AC only B model only allows the user to program the differential off setting. the differential off setting is preprogrammed at 4*F. This is actually an ideal setting for almost all systems. The freeze and boil protection settings are not essential for most solar heating system but they are a nice option for warm sunny areas where freezing is a rare occurrence and antifreeze is not used.











 





AC only Basic Differential Controller with probes                                    $75    USA shipping only

AC only Programmable Differential Controller   with probes                      $150    USA shipping only                

If you live outside the US contact us for shipping rate

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