Q: My home was inspected, and the buyer wants me to extend the vents. There was no other explanation, so I don’t know where to turn. The agent has not been very active in helping us, and the inspector won’t return our calls. Can you provide some insight?
A: When a home is inspected, there should be written information supplied to the buyer, and, in most cases, his or her agent. The buyer’s agent then passes the information to your agent and finally to you. Somewhere in all of this the system has failed you.
There are plumbing and heating items in a home that must be vented to the outside. Plumbing vents allow sewer gases to escape and provide air to allow the waste pipes to drain properly.
Then there are the furnace and water heater vents, which must also vent to the outside of the home. A plumbing vent is usually a plastic pipe vented through the roof. In areas with significant snowfall, the vent needs to be at least 10 inches above the roofline or above the annual snowfall. If the vent is on an outside wall of the home, it still must vent above the roof. I sometimes see a vent that is near ground level or ones that end under the overhang of the roof. This is not acceptable. The same is true for furnaces, water heaters and radon mitigation vents.
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The two separate vents for a water heater and furnace can be combined into a single flue. When there is a single flue pipe, the water heater must be connected above a point where the furnace is connected. A vent for flue gases is normally smooth walled metal unless you have a 90 percent or higher efficiency furnace or a high efficiency water heater. High efficiency furnaces and water heaters can vent separately through a sidewall using PVC plastic pipe for the venting.
Why the difference? High efficiency units have induced draft systems to force the flue gases to the outside and generally produce mostly water vapors. Now that you have some idea of what to look for, here are some guidelines for venting high efficiency units: A high efficiency flue should be at least one foot above the ground or 7 feet above a walkway, at least 4 feet below or beside a window, door or air inlet such as a clothes dryer, bath fan or range hood vent. The flues can be no closer than 3 feet to a gas meter regulator, which can occasionally release natural gas.
Call your agent and ask for a copy of the inspection report or a written explanation to better understand what needs to be done.