Return visit to diagnose issue with no heat on Aqua-Balance combi boiler. Homeowner does have domestic hot water. Determined that the 3 way valve has failed. Provided a repair quote to the homeowner. The system is out of its 2 year parts and labor warranty. Collected diagnostic fee from 4/24/23 and 50% deposit towards repair quote. Weil McLain M#AB-120-C, CP7509520.