Foo - hot water heater question - since we're all plumbers here ;-)

So, I'm sure this is a general enough question for those that know:

Last night I heard knocking coming from my hot water heater. I took the day off of work today to fix the darned thing, and I hope I spent my day off wisely by flushing out the hot water heater correctly.

I turned off the gas to the hot water heater. Attached a garden house to the spout on the bottom of the unit. Turned off the cold water supply. This is where my question comes in at... I read that you need to open the pressure relief valve at the top of the water heater, but when I did, hot water just pours out. I filled bucket after bucket of hot water (which was dirty, rusty, and had white stuff at first), till I decided to just close the valve, and open the valve where the hose is attached to let the bottom drain out. I let it drain till the water was clear.

I hope I didn't just waste a PTO day by not doing the right thing :(

I guess I'll find out later if it's still knocking...

Try your question here (http://www.terrylove.com/forums/index.php). I've gotten good results from them.

My newish(?) water heater knocks. I have never heard a water heather not knock. What does the knocking mean?!

Did you open the little door on the side to see who was there?

Here.. http://home.howstuffworks.com/water-heater1.htm

My newish(?) water heater knocks. I have never heard a water heather not knock. What does the knocking mean?!

Thermal/pressure relief valve will occaisionally bump. Air anywhere in your house supply will cause knocking. When does it knock and is it more of a crackle (tank being heated causing expanding and contracting)?

Oh, if you have corrosion, you may need to replace the anode.