Water Heaters - fumes from top of water heater

I moved into a new house a month ago, like a week ago i started smelling something in the kitchen that was almost a gas smell. I couldn't figure out where it was coming from. Then yesterday the smell got so bad that most of the house was smelling like it. I realized it was the same smell that is coming from the top of the gas water heater. The water heater was running fine, except for some pings in the pipes, but I had to turn it off because the smell was making me sick. I'm guessing it's a problem with the exhaust system. Anyone have any experience with this. This is my first house and the first time I've ever had to deal with any gas appliances. I'm worried the entire exhaust system has gone bad because I have a gas furnace that heats the house and a small gas furnace in the basement that all run through the same exhaust system.

Thanks

You're going to have to have the flue piping disassymbled and checked for obstructions. many time birds and squirrels will get down in them and block the pipe.

You seem to have a venting problem. This can be confirmed by holding a lit match near the draft hood while the burner is on. The match flame should be drawn towards the vent.

The cause of the problem can be many: blocked flue; lack of sufficient combustion air supply ( where is the WH located and what else is in that space?); reverse draft caused by another heating system and/or a furnace.

Tell us more about the situation.