A friend had a new gas boiler installed last winter. Over the past few months, she noticed a smell (something like oil) in the basement that comes and goes. She called the boiler people, who said there's nothing wrong with the unit, but suggested that maybe her neighbors had poured oil into their basement sewer and it had backed up into hers. She had the sewer line rodded out; the plumbers discovered a cracked drain pipe and replaced it. But the smell comes back occassionally, regardless of whether the boiler is on.
She's thinking maybe the vent for the boiler and/or hot water heater is blocked.
Any other suggestions on what to check?
Karen