I have the above hot water heater. I'm pretty sure it is the original water heater that was installed in our home when it was built in 1994. I also would assume the previous owners (including myself since 2005) never drained it yearly to reduce the sediment. There is a label on the heater that says it has Hydrojet technology, which means it may have an internal fan that churns the sediment and drains it (although I've never ever noticed it draining into the drain in the basement)--who knows, maybe that feature no longer works as it is probably 15 years old now. I do notice less hot water in reserve these days, so I am assuming it is definitely filling up w/sediment, reducing the volume from 40 gallons to who knows.

My question is this: Even though the tank is probably 15 years old and probably never has been drained to reduce sediment, is it OK to do it now? It is a natural gas unit, one person told me it is safe to do so as there should be nothing inside to damage. Another person told me that draining it would do no good as a lot of the old hot water heaters had plastic dip tubes that slowly dissolved over time as the sediment layer rises.

So, can I drain it, or should I just up the temp for a while until the sediment rises to the top and I pretty much have no hot water in reserve (and then buy a new hot water heater)?