Does an interior chimney need to be lined?

John Starcher_4

....to be sure, but I would say yes. If you are converting to gas from oil, the answer is a definite yes!

Starch

Jman

Does an interior chimney need to be lined?

Does anyone know if when converting to gas boilers, does an interior chimney need to be lined for code compliance in Nassau County?

Brad White_2

What is being vented

into the chimney? (Not speaking to the code aspects especially in Nassau County). Technically and in my experience, I have vented an atmospheric-fired appliance into an interior unlined chimney for years without a problem. (I since went to a direct-vent Monitor MZ so the chimney is now dormant.)

However, IF you are going to vent a high efficiency appliance (condensing boiler or something in the range of 86% or better in some cases) manufacturers warn against it. Also if it is positive draft (forced outward) and the chimney leaks or has restrictions, the gasses may go through the brick and openings into your living space.

Jman

I'm venting 2 GM-05 gas Peerless boilers. If you think it needs o be lined, what would you line it with1)Stainless, 2)Aluminium, 3)cast in place and what diameter?

Robert O'Connor_7

Jman..

Goldie Locks Saves the 3 Bears from Certain Asphyxiation:
The last time we saw Goldie Locks, she was a mere child being chased around by 3 bears. But alas, Goldie has grown up and is now an appliance installer. As we peek in on Goldie Locks, she is attempting to connect a furnace to one of three vent pipes in the three bears house. The first vent pipe was toooooo small, the second vent pipe was toooooo big, but the third vent pipe was just right.
At one point we were simply worried about vent pipes being big enough but as technology has progressed, we are now worried about vents being too big. Vent pipes for new Federally mandated mid-efficiency appliances have to be "just right" When a vent pipe is too small there isn't sufficient area to vent the products of combustion. When a vent pipe is too big it will be subject to excessive condensation. The corrosive nature of this condensate will cause the vent pipe to deteriorate.
This issue, as well as the dangers associated with vents and chimneys that don't funtion properly have led to incresed concern about using existing chimneys and vents when appliances are being replaced. You have probably seen some articles on the subject. An article called "Carbon Monoxide--The Silent Killer" , "Danger Lurks in Local Neighborhoods: Dangers of Carbon Monoxide," written by George E. Lucia and Trica Branley of Hillsboro, NJ and it appeared in the Feburary 1994 issue of New Jersey Municipalities Magizine. Both of these articles are worth reading.
Some questions I ask as a aplicant who is proposing to use an existing chimney or vent with a replacement appliance are:
1. Is the chimney/vent clear and free of obstructions?
2. Is the chimney lined, and is the liner in good condition?
3. Is the chimney/vent size appropriate for the new appliance?
Often it is not possible for an inspector to see the inside of the flue or chimney. In most cases, an inspection is done after the new appliance is installed. For this reason getting some certification about existing conditions from the installer probably makes sense and is in fact code in the great state of New Jersey (counter form: F370). In addition, a spill test performed by the contractor should be performed. If possible, this spill test should be witnessed.
We now return to Goldie Locks, who has just completed the furnace installation in the 3 bears house. The 3 bears are so happy with the installation that they don't chase Goldie Locks out of the house, but rather, invite her to sit down and have some porridge with them. And they all lived happily ever after--untill the bears got the bill. Papa Bear thinks Goldie Locks' prices are toooooo high!
The End.............Robert O'Connor/NJ

Brad White_2

I do not have the input handy but the manufacturer would have data on a recommended flue diameter and height. If to be lined, my first choice is stainless (good corrosion resistance balanced with cost). AL-29 4C is nice if you can afford it. If you go refractory, I do like the Perma-Flue system but it is not necessarily allowed in all jurisdictions. It is allowed here in MA but only for retrofit situations.

Dale

Depends

Ask your local inspector. NFPA 54 10.5.4.1 covers this and requires cleaning if going oil to gas. It says must be lined (.2)but yours may already have a tile liner. The cost of a nat gas liner is very reasonable and it comes with a listed cap. The liner with B Vent connectors will heat up quickly and provide a safe system.