Solar Differential Control
Differential thermostatic control is the best way to insure a net heat gain from the sun. Some controllers not only regulate heat flow but they also monitor collector and storage temperatures. Some controllers use multiple relays that control pumps and electronic valves� AND some controllers use separate controls for both the differential on and differential off settings. All of these things are fine� BUT remember the most important job of any solar controller involves the activation of a pump when heat is available for collection. For this reason I have developed a rugged basic differential controllers that respond to solar heat availability.
Conventional on demand heaters rely on the convenience of fossil fuel energy concentrates. Only one temperature sensor is needed to activate the combustion process within a furnace. Solar heating systems are a bit more complicated. They rely on the intermittent nature of sunlight and two temperature sensors.
The solar heat available for
collection is the driving force behind the differential controller. Metering the
actual collector and storage temperatures can be interesting but it�s not an
essential part of the heat collection process.
This is a basic differential controller with most of the components enclosed. There are two indicator lamps. One turns on when the pump is activated and the other one glows in proportion to the heat that's available.
Pins 1 and 2 are used to connect the relay to the pump. Pins 3 and 4 are used to connect either a PV supply or a Wall Wart 12VDC supply. The last three pins are used to connect thermistor probes to the enclosed differential controller.
Remember the main function of a differential controller involves the regulation of a circulator pump based on the temperature difference between the heat collector area and the heat storage area. Heat is monitored with a single LED that glows in proportion to that heat availability.
The relay can handle up to 300 watts of power and it may be used to regulate either AC or DC pumps.
The differential pot adjustment is used to strike a balance between heat gain and energy conservation.
Polarity protection is also included incase the user mistakenly reverses the power supply.
This is a tough little differential controller designed to simplify the the hook up connections as well as the differential settings.
I also have a few controller kits left that only
use one LED to indicate when the pump is on
MTD Solar Collector Kits
Solar Heating Controller
12 Volt Differential Controller
Basic Differential Controller KIT
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MTD Solar Heating
MTD Solar Home
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Solar Heating in December
Solar Heating in January
Multi Tank Heat Storage
DIY Solar Heating Panels
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Gallery of Solar Homes
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Sustainable Solar Heated Workshop
Sun Money from a Solar Workshop
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Solar Heated Roof