I bought a house that has an older model gas furnace with a brick chimney and when it rains I get water coming out of my vent pipe in my basement just before it attaches to the furnace. I do not have a cap on my chimney and was wondering if I should install one and if so what king should I buy? On top of the chimney there is an 8x11 ceramic tile. I see everyone else on the block has a cap on their gas chimney and was wondering why mine doesn't.

I don't understand the ceramic tile. Is it up on supports over the chimney? Otherwise, you should be able to buy any simple cap. Perhaps the original simply blew away.