Hard White Pellets in Waterline Following Heater Repair
Several months ago we had a heat coil replaced in our water heater. All was fine until a few weeks later when we started getting clogs and low water pressure in all our faucets (kitchen & bathrooms, can't tell about the dishwasher or washing machine). After taking the faucets and showerheads apart, we found small white hard pellets lodged in them. After shaking them out all works good for a few weeks and then they become clogged again. Now we can't find any pellets in one showerhead but we have almost no pressure. The service that repaired the water heater had no ideas as to what caused this but I'm thinking maybe they left in some packing material that is slowly dissentegrating. Any thoughts?
That's calcification breaking loose and "clotting" in your valves and strainers. It is normal, but can be minimized by routinely draining the water heater a couple times a year. I seriously doubt that it is packing material.
Now that you are stuck with the fragments of sediment you might try draining the hot water tank (not all the way, just six inches below the top will do). Then open several hot water faucets and one at a time back flush the lines that are giving trouble. You'll have to be careful to avoid squirting water all over the place.
Sometimes turning on the cold faucet while the matching hot water faucet is still on, the entire hot water system is still off, and the tank still has the air space will do the backflush.
Hopefully any remaining pellets will come out a few at a time later when you turn everything back on.
Don't force any faucets. Crunching down on a pellet can damage a faucet washer.