Hot water tank flame

[Rburt5]

I just finished draining my hot water tank to get rid of sediment. I relit the pilot as the directions said. No problems yet. Then I turned the thermostat to "Hot" and lit the heating element. Everything seemed fine, but now the flame is making a spitting sound as if something keeps dripping into the fire and burning up. I don't smell anything. When I looked in I could see what appeared to be some kind of ash-like substance that was falling through the flame and burning up. Could it be bits of rust or droplets of water? It has been going on for about 10 minutes, and I plan on turning it off if it continues much longer. Anything with gas and a flame makes me worried. Any ideas? Is it dangerous?

 

[Rburt5]

Update: I think it was drops of water from condensation on the underside of the tank. I had just flushed it out with cold water. In any case, it stopped after about 15-20 minutes.

 

[Sponsor]

 

[Redwood]

Well you have figured it is what I was going to tell you it was.

 

[Jimbo]

You hit the nail on the head. There is a lot of moisture in the combustion product of natural gas. That warm moist air hits the bottom of an ice cold tank and bingo....droplets of condensation form and drip back down, causing the hiss. Once the tank is heated, then in normal operation this will not happen much, as the tank will be warm, except in instances where you really run the hot water full blast for a while and cool off the tank.