Web monitoring


View live data feed from select solar thermal systems utilizing the Delta-T Pro controller

Listed below are some common general questions regarding the Delta-T controllers.  If your problem is related to network setup or network connectivity, download the Network Start-Up, Networking Reset, and Troubleshooting manual from the Manuals quick link.  If none of these FAQ's address your question, please call Heliodyne customer service at 888.878.8750 or email us.


General Controller Frequently Asked Questions

Q: How to I get help with troubleshooting?
A: If your question is not listed here, refer to the troubleshooting of the manual which can be downloaded here. If your question is still not answered, please call or email us.  


Q:  How can I tell if my thermistor sensors are reading properly?
A: Heliodyne uses 10kOhm thermistor sensors. They are inversely related to temperature, so the higher the temperature, the less resistance the sensor exhibits. An open sensor input, which is infinite resistance, conveys the lowest temperature. A shorted input, or zero resistance, conveys the highest temperature. To find resistance values for Heliodyne 10kOhm sensors, download a print chart with values here


Q: How can I tell if my controller is working? 
A: An easy way to test any Heliodyne differential controller is: first, remove all sensors from the controller. Take a piece of wire and connect it across the collector sensor T1 input. This will activate the solar relay. Now, placing another short across the storage T2 sensor input shuts off the relay. If the controller performs these functions it is operating properly.


Q: What voltage and power input does my controller require?
A: The Delta-T controller can be ordered in 12VDC, 120VAC, or 240VAC models. Each consumes approximately 6W. The Delta-T Pro can be ordered in either Ethernet or WiFi configuration; either model can be configured for 120VAC or 240VAC use on site. The Pro consumes approximately 11W when networking is active. 


Q: How big of a pump can the controller handle?
A: The Delta-T controller has one SPDT relay, with 1/2Hp capacity. The Delta-T Pro has 3 relays, the Solar relay 1 is a SPDT, and the normally open contacts have a 2Hp capacity; the normally closed has 1/2Hp capacity. The Delta-T Pro relays 2 and 3 are SPST, with 2Hp capacities each.