Cooktop lights fine, water heater is fine, fridge is fine.
"Is the pilot flame close enough to the thermocouple?
Apparently it is; the pilot lights just fine and stays on as long as you would like. It's only when you light the oven burner that the problem comes up. Pilot goes out after about 3 minutes which in turn kills the burner by design.
BTW, I read a thread about these having and undersized orifice that the mfg was aware of. Don't know if that's it. With the pilot working fine on its own, I think we can rule out the thermocouple.
