Galvanized Chimney Pipe

Once again everyone Im back with a newb question. My chimney is made of 5" Glavanized metal Duct work. Single wall 30 ga. stuff. and all the seams and joints have been sealed well with a good stove cement. But while talking with a stove company out here, (wanted a 5" tee) I was told that thats not really a chimney and galvanized metal puts off poisonous fumes. Now after a little research, I found that what they are refering to is zinc or more specifically zinc oxide. I looked up the melting temp and boiling temp and found that it melts at 1975 deg. and boils (releases into gas form you can inhale) at 2360 deg. That being said, why should I worry about it. My stack never goes over 220 deg. and I don't weld anything. So am I completely off my rocker or is this setup ok for my garage that I work in. I know ash can sit in the chimney and when it gets wet will form an acid that will rot out the pipe but Im ok with that because to replace the entire chimney with new it would cost about15-20 dollars. Is there any real danger in using this pipe as a chimney?

markplusone wrote:... My stack never goes over 220 deg. and I don't weld anything. So am I completely off my rocker or is this setup ok for my garage that I work in. ..?

Your stack will get higher when you first light the stove up, I should think.
I don't like to mess around with the intial startup, so I get mine "hot".
At 500, I'm sure you would get an unpleasant reaction.
That is when you would get the smell/fumes... but at 220 or so, I don't think it would bother you at all.
So make sure, if you do start yours like I do, keep your garage door open for a bit..
But I can tell you, that those fumes when present, will send you to the bathroom multiple times!
The first time I cut some galv. steel with a torch, was the last time....

Dan

I used to burn & weld a lot of galvanized, just try & stay away from the direct fumes & if a headache starts coming on drink milk. The cheap gal. crap we get now will not only give off more fumes but will start to even flake off, i`d be leery using it.

Unless you use a torch or welder on it I don't see how you can get any fumes from it. When it does off gas, you will see a white, very lazy smoke. The only real danger I know of is if overheated, the galvanize will break down and tends to come off the steel in a fine grainy dust. You can get it on your hands and/or in the air and ingest it. The stovepipe will also rust. It can be used but the manufacturers of galvanized pipe do not recommend it for solid fuels. That said, I myself have used it in the past and many members here still do. I know of no instance where it has caused any deleterious effects.

I've been using galvanized on my oil fired furnace. Its about a 6' run to the chimney. I've seenthe stack temp on that around 800* never ran into a problem. But then again, I don't spend too much time in the basement and the furnace only tends to run on very cold days when the Chubby can't keep up.

My son just returned a bunch of Gal. to a supply house, his hands were covered in a fine dust just from unloading it & when he tried to crimp it a little some of the galvanized just came off. They gave him some old stock to replace it & they marked the newer shipment to not be sold, you can guess where it came from.

samhill wrote: you can guess where it came from.

Haw haw haw, me Chinee me play joke me put bad galvanize on your smoke-------->pipe!!! Haw haw haw Joe!!!

Not sure what stove you have but a quick review of the Harman hand fed on-line manual for the Mark Series on the first 1 or 2 (certification page in fine print) requires a 24 gage min black steel or 26 gage min blue steel pipe.Your 30 galv does not meet that spec from two perspectives regardless of the tech reasons. You can review this 24/26 data in the Harman website for the coal stoves, it's a .pdf file. I'm of some opinion that this represents a appropriate cert/code level for just about any handfed though that is just my opinion subject to change.

We don't talk about the reality of insurance companies or building approvals here , but the reality is if your stove overtemps (like leaving your ash door open in a hand fed) and you have a fire, the insurance investigator will inspect this sort of stuff and find out you may not have a certified system (or a legitimate building permit), suggesting the insurance company may try to make this a issue for non/reduced payment.

Good Luck.

That's a good point about the insurance companies, having said that galvanized flue pipe has been the standard here in coal country for decades..

I have 5" dia 26 ga galvanized pipe on my stove, made in Canada. Used it all last year and so far this year. Have seen the temp as high as 500 near the stove. Hasn't killed me yet. I'll get back to you if it does

Bruce

Richard S. wrote:galvanized flue pipe has been the standard here in coal country for decades..

But probably not 30 gauge... I doubt that would pass any code.
That is used for heat distribution in a hot air system..
I'd want 24, same as for the black..
(IMO)

Dan

Yeah I do agree that if I intended this chimney to last more than one season, I would go for a bigger gauge material. But since its not, and because the chimney that is there has been that way for what ive been told 20-30 years, I don't intend to change it. For me, its a simple cost issue. I can replace half of my chimney for the same price as one 2' section of straight black pipe. Even with the extra gauge of metal, the clearances are all still the same. Your just as likely to set your garage on fire with 24 gauge as with 30. They both wear out especially when water has a way of getting in to mix with the ash (which makes a caustic residue). So if the "fumes" off of galvanized arent going to kill me, Ill pay 25 dollars and an hours work a year for a new chimney. IMO if you are using a snap together steel chimney outside, you are wasting your money. They wear out too quick to overcome the extra cost of material.

zinc fume won't kill you. It will take much more than burning a little of the zinc off one of your galvanized pipes for you to begin to get zinc poisoning - and even then the excess zinc in mild cases can leave your body in as little as 24hours having caused NO lasting problems. Zinc "Poisoning" is a temporary mostly harmless result of having far too much zinc in your body; it is not something that happens with a limited, mild exposure to zinc or zinc fume, it feels like the flue, and your body will pee out the excess zinc. Within a few days, you will feel back to normal. Of all the things out there to worry about that are poisonous and toxic, zinc is not one you should lose sleep over.

Your stovepipe surface has to be well over 600ºF to give off any zinc fume. I run galvanized on everything- except for the stove in my dining room that occasionally sees some wood. As far as the gauge of the metal, don't worry about it; for coal stoves 24,26, or 30 gauge makes little difference. whether the connecting pipe has to be replaced every year or two (30 gauge) or every 3 or 4 years (26gauge) makes little difference - it should be inspected yearly either way. Because you're not burning wood it makes little sense that there is any saftey issue - your flue temps will never approach that of even a mild flue fire that can melt light gauge connecting pipe.

looking for pipes that last!!! tried stainless of unknown type, cheeper galvanized + lastly the costlier heavier blk heat fab did the best BUT 3 years now + prolly wont be good any more. my oil furnace pipes never rust or pit + guessing the oily greasy film inside them protect them. with todays price gouging + pretty EZE DIY guessing the cheeper galvanized ones of a heavier gauge will be my choice

Stovepipe manufacturers don't recommend galvanized for solid fuel applications.