Chimney liner?

JohnNY8

When do you need one?
When do you not?
It seems there are many opinions associated with those two questions.
What are the facts (or "facts" in your opinion)?

Thank you.

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Firedragon_4

Read!

This is a good place to start.

http://www.protechinfo.com/

I send a lot of techs and homeowners here. I know since I did a liner, my noise level has dropped a lot!

Constantin

Call me a worrywart...

... but I would always line a simple masonary chimney. Most of them have single-brick-thick walls whose decaying mortar may or may not keep the flue gases out of the house.

Well-built chimneys at the center of a house with clay liners are a step up, but only if it's an older appliance feeding them (i.e. hot stack temps). Exterior chimneys will always have draft/condensation problems with more efficient heating appliances, so they should be lined regardless of what is feeding them.

Another thing to consider is getting a proper draft. Hooking up an appliance that needs a 4" round flue to a 12"x12" chimney is a sure way to get condensation raining down. A liner will ensure that the air-speed stays high enough to get most of the flue gases out of the house before they can condense. Also, a small liner has much less mass and surface area to condense on...

We rebuilt our 45' high chimney from the ground up (the draft is great!) On the inside, we have smooth-walled stainless pipe, a insulative wrap, perlite, and the masonary component. I'd like to think that this setup will allow me to run very low flue temperatures w/o any issues from condensation.

DaveGateway

What do I tell my customers?

It seems that I'm asked this question all the time - "Do I need a liner". To top it off, my chimney guy just told me I need a liner (as proof, he showed me a handful of terracotta chips at the base of my chimney). Is it ever a bad idea? I'm talking about residential natural draft steam & HW replacements (gas and oil-to-gas)in 75-100 year old houses.

Steve_35

The best thing to do is get a copy of your state code

Follow that as a minimum. You'll be doing more than probably 75% of the contractors.

One of the most common problems I see is a new WH w/a 3" hood installed running into a chimney with an 8x10 liner or some such. Looked at another today installed by one of Sear's finest. With 3" aluminum connector. Not only did they leave the old water heater but also left the box the new water heater was in.

Firedragon_4

Here's another source,

but now that you've become more specific if you are burning gas a liner is a must in a masonry chimney, with oil it's a should have.

http://www.csia.org/

BTW, another thing is not to get involved in the liner at all, just recommend it and let a CSIA member handle the rest. Everyman to his own profession.

Ken D.

liner

The heaters made in the past 20 years or so have stack temperatures much lower than the older units. This results in the chimney being cooler resulting in condensation. This condesate is acidic and breaks down the terra-cotta and mortar in a masonary chimney. Lining the masonary chimney with stainless steel and vermiculite insulation keeps the chimney warmer and the stainless is not as affected by the condensate.

Dean_7

Pictures of unlined chimney moisture damage

When these pictures were taken this chimney was 93 years old. It had served a coal fired boiler and an oil conversion of that same boiler for 87 years without a problem. This damage was the result of moisture condensation inside of the chimney after the oil conversion of the boiler was replaced with a gas conversion. The chimney was lined at the time of the gas conversion but with ordinary galvinized single wall pipe (WRONG). The flashing between the chimney and the roof was completely intact. The acidic condensation from the gas burner on the boiler due to lower stack temperatures ate through the galvinized liner and through the chimney in less than six years and did the damage pictured. The house had been vacant for two years when I aquired it but the heat had been left on. If this isn't a case for proper chimney liners I don't know what is. When we demolished this chimney the mortor between the bricks (what was left of it anyway) was so bad you could simply pick the bricks up whithout any effort. There was literally nothing left of the liner except a few pieces of shredded steel.

Bob Harper

When NOT to reline

When the chimney meets the existing codes, is properly sized for the appliance(s), and is suitable for the expected use in general. Otherwise, you always must reline. Since you won't find a single chimney that meets all these conditions, you always must reline-period. BTW, ASHRAE, IFGC, NFPA 31,& NFGC all point you to NFPA 211 as to what a chimney is and should be and how to inspect it. If you change an appliance type you should be performing a Level II inspection per 211 and either rebuilding the chimney or relining with a listed liner installed to the listing.
HTH

JohnNY8

NFP 211

Is that found online?

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Bob Harper

online codes and stds.

www.nfpa.org

hth