This controller is designed specifically for solar heating applications where the circulation pump is powered by a solar panel or DC power.
The DTC-AT will improve the performance of any DC powered solar heating system. It will switch power to the pump when it determines that one sensor (S1) is hotter than the other (S2). More importantly, it shuts off the pump when the reverse is true. The DTC-AT has an adjustable differential temperature allowing the user greater flexibility.

The DTC-AT will prevent the loss of stored heat when collector temperatures dip below the stored water temperature by preventing the pump from circulating cooler water into the storage tank.

Recommended for Pressurized glycol systems and can also be used for Drain-back type systems (see instructions).

Features	DTC-1	DTC-AT
Operates from 3.5 to 30 Volts Operates pumps rated for 12 or 24 Volts	yes	yes
Uses standard 10K thermistor temperature sensors Order separately by the pair, available here.	yes	yes
ON/AUTO/OFF switch to simplify testing	yes	yes
Fixed differential < 1F	yes
Adjustable differential 5 to 35F		yes
Adjustable max temperature shut down senses storage temperature		yes
Over temperature warning for storage red indicator on front panel		yes
Pump run indicator green indicator on front panel	yes	yes
Switches up to 6 Amps (72 Watts) Or higher with external relays	yes	yes
Replaceable 6 amp 3AG type fuse inside	yes	yes
Built in surge protection protects electronic motors	yes	yes
Ambient Operating Temperature of controller -40 - 185F  (-40 - 85C)	yes	yes
Dimensions (not including mounting ears)	2.5 X 3.5 X 1.25" (65 X 88 X 42mm)	2.5 X 4.75 X 1.25" (65 X 120 X 42mm)
5 year limited warranty provided by ART-TEC	yes	yes
Made in the USA	yes	yes

More Information:
 Download the Installation & Application Manual