Went in yesterday to service a furnace in the Loft that we own on report that there is no hot water. Did regular checking but could not get it restarted. Had to call in a service - they replaced flame sensor and igniter combo and it fired up...

As a last check they visually inspected the vent lines from the w/h and discovered that a huge bees nest had completely blocked off the vent pipe - that was the reason the water heater kept cycling on and off until it burned out the vital components.

For the benefit of other folks reading: if your warter heater works intermitenttly for no apparent reason - check your air lines - both input and exhaust and be sure they are unobstructed. Sometimes it's the basic stuff...

Yep, had that happen Dec 23 two years ago. Luckily I checked as the unit was vacant. Frozen pipes but no burst.