Need technical help with troubleshooting tips for water pump and controls for solar water heating system.?

Question

This is a 20 year old solar water heating system that has been woking fine up until just recently. It has a Grundfos A8207 pump, and Heliotrope General Delta-t+ DTT-74 control box. The lights at the control box indicate power there, but the pump does not appear to come on (even when switched to "manual mode"). How do I determine if the problem is in the pump, or in the control box? There are no obvious frayed wires etc, and no other apparent damage. Any helpful suggestions will be very much appreciated. Thank you.

Answer 1

If you have the correct voltage where it is wired to the pump then your problem is the pump