Venting gas furnaces/hot water tanks in a chimeny cavity


Need to know some ruling on venting gas units (furnace, hot water tank etc. ) in teh cavity of a chimney.

Can you vent these fixtures straight into a chimney without an inter liner or piping system.

I have heard that it will no longer be allowed to use the cavity without a liner.

If this is so, then is the rule a nation wide or local ruling?

thank you

The combustion products produced by burning gas appliances with deteriorate the mortar over time.

So the answer is No.

All “rulings” are local, Bill. Federal rules applied to the building industry are generally environmental in nature, but even they give way to local rules that are of equal or greater restriction.

Your most accurate answer to your question will come from your local authority having jurisdiction.

Gas Appliances & Your Masonry Chimney

What you don’t know about your chimney can hurt you – especially if you have a gas-heating appliance that uses your masonry chimney as a venting system. Every day, without any visible signs, acid produced by your gas appliance may be eating away at the inside of your chimney.

The resulting damage can compromise the safety of your family and the value of your home. But thorough annual inspection of your chimney, as recommended by the National Fire Protection Association and the Chimney Safety Institute of America, can alert you to potential problems before they become costly or dangerous.

Most homeowners are aware of the need for chimney cleaning and inspection if they own a wood-burning stove or regularly use their fireplace. But many don’t realize that gas heating appliance – whether it is a furnace, boiler or even a hot water heater – relies on the chimney for proper venting of the exhaust.

Appliances fueled by natural gas or propane may not produce the visible soot that appliances burning other fuels do, but they can deposit corrosive substances in your chimney. In many cases, these acids may wreak havoc on your chimney without producing any external symptoms until the problem has become dangerous or expensive to repair.

Thanks for the reply’s.

Does a ceramic insert in the chimney cavity pass code?

The furnace people say that when you take the 90 plus effiency furnace off the chiminy
you need to put a liner in the chiminy to protect the flue . but the hot water heater is
just fine in the summer months without the furnace than??