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Rick, HVAC Supervisor
Category: HVAC
Satisfied Customers: 21765
Experience:  40+ yrs. experience as a licensed oil & gas technician.
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Problem with my Weil McLain HE-II-6 gas boiler. Intermittently,

Customer Question

Problem with my Weil McLain HE-II-6 gas boiler. Intermittently, it will shut down. The flame/valve red light on the controller will be flashing. Turning the power off momentarily restarts the boiler until the next time it happens. It's much more frequent in cold weather. In mild weather, the boiler runs normally and this almost never happens. Now, when it's cold, it happens 2-3 times a day. What's wrong?
Submitted: 7 years ago.
Category: HVAC
Expert:  Rick replied 7 years ago.
HiCustomerbr />
I suspect you have a problem with the flame sensor. The 2 series used a mercury flame sensor that can be problematic. It's probably happening more during cold weather because the boiler is running more.
Customer: replied 7 years ago.
How do I know if I have a series 2? According to nameplate, it says HE-II-6, built in 1991.

Where is flame sensor located? My parts info shows a flame rollout thermal fuse. Is that the same thing?
Expert:  Rick replied 7 years ago.
That's about the right age for a 2 series. The flame sensor should be heated up by the burner flame so it's in the combustion chamber. It has a stiff silver wire attached and a cube-like end that plugs into a control socket.

Understand this is only a possibility and I'm not telling you to replace it. This service is not meant to substitute for professional onsite diagnostics

Ther thermal fuse is usually an all or nothing device. It's unlikely to cause an intermittant problem.