Runaway Boiler
Posted by Robert Marr on June 09, 1998 at 20:24:17:
Coming home to an 80� house in 65� weather isn't good, especially when the zone valves are all set to 63�!

I have a 2 year old Vaillant boiler with Honeywell zone valves and a Honeywell Aquastat relay, type L8148E. Since the zone valves were all energized, I assume something on the relay board has gone south. Does this seem reasonable? If so, does the board have to be replaced as a unit? OR, can the individual components be replaced? Of course, if this isn't the problem, does anyone have an idea where to start looking?

Also, the water temperature had reached 190�, considerably higher than the output from our old boiler. Is this near the temp that you would expect to see the pressure relief kick in?

Thanks. Any advice will deffinitely be appreciated!

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