After further inspection of a home my wife where looking to purchase in CA I noticed that one of the upstairs bedroom closets had a 2ft square wooden “box” running from the floor to the ceiling. This “box” was nailed in but not ait tight. Further investigation showed that the gas forced air heater flue pipe was behind the “box”. It was one long piece of pipe and did vent to the roof. However if the flue pipe was leaking wouldn’t it leak into the bedroom and possibly kill someone? This can’t be safe. I think I know now why this house has fallen out of escrow twice.