Good evening. Last week I had to troubleshoot a Weil McLain Ultra, 3 years old. The DHW circ. was not functioning.The cylindrical fuse was jumped, and the flat fuse was blown. When I disconnected the manual reset high limit,(Honeywell L4006E), the circulator turned on after replacing the flat fuse. The L4006E shows no continuity resistance. The manual reset is wired to the terminal strip for external limits. Also, the external manual reset aquastat is required by code here.
When I reconnect the aquastat, the Ultra locks out on "Limit Open". Any ideas?