 But then about three or four days later, we turn the furnace on and it draws the sewage gas air again. Well, let's talk about this. So first of all, what water from the furnace is being drained into the sump pump? Are you talking about the condensate line from the air conditioning system? Yes, sir. Is there a return duct in the basement area where this is or in the room where this is? Or do you think it's coming in through the drain pipe?