How many older homes do you think are standing in the U.S. that have unlined brick chimneys or have a single flue that currently services two or more fuel burning appliances? Five, 10, 20 million? I don't know the answer, but I would say it is very close to 20 million. One thing is for sure, there are millions of houses that currently have lower efficiency gas furnaces that vent into a chimney. These furnaces will probably be replaced within the next 10 to 15 years with high efficiency units that do not vent into a chimney. If your house is one of these, you will need to deal with an older masonry chimney that very likely will be too large for the orphaned appliances in your house.

Stainless Steel Alloys

This is where the stainless steel alloy chimney liners come in. These products allow you to create ideal drafting conditions using an oversized masonry chimney. A flexible metal pipe is snaked into the chimney extending from the top of the chimney to the thimble area where the vent pipe attaches to the chimney. As you might expect they come in various sizes and materials.

One might think that the ideal material for these liners would be high grade 304 stainless steel. Well, the flexible pipe manufacturers tried this and the chlorides in the exhaust vapor of natural gas caused corrosion. So, look for stainless steel alloy liners that carry this labeling: AL 29 - 4C. This is your assurance that you are getting a top quality metal flue liner.

Pipe Companies

Also pay attention to the warranties offered by the different pipe companies. They are not the same! It is also a great idea to ask for installation literature. You should always read this literature, even if you don't plan to install the pipe yourself. Knowing how to install the pipe allows you to ask pointed questions of the contractors you interview. If the contractor can't answer the questions, you know you have a rookie! Don't try to install these pipes if you have the slightest fear of working on roofs. It is dangerous work!

The companies listed below are wholesale distributors. All of them make flexible pipe but some make rigid pipe as well. Be sure to pay attention to sizing! Don't get a liner that is too small or too big.