I have an electric water heater that is less than 5 years old. I have replaced both elements and the thermostats but get no pressure coming out of the water heater into a "Manablock" (sp?) water distribution system. There is water pressure going into the water heater, the cold water has a great deal of pressure but none from the water heater itself. Replaced a copper tube to make sure that no "junk" was in the line. We've got super hard water even though we have a whole house water filter installed. The filter was just replaced a couple of weeks ago so that isn't the problem.

Any advice?

Thanks.