Coalpail.com Forum

I'm on my third year with Duravent, and I'm amazed at how quick it seems to be rusting. My cap and bottom-tee cap both rusted to failure the first season. Convinced the company to replace them under warranty, but they told me I must be burning "low quality coal" and that they wouldn't be replacing them again. I knew it wouldn't last forever, but wow! The straight sections and tee themselves seem to be holding up a little better, but are visibly rusting inside and out. At the end of each season I've disassembled them, brushed them out, and stored them in my garage, hoping to prolong the inevitable. My black iron pipe inside the boiler room has also rusted to failure more than once in the few years that I've been running my boiler. Looking back I guess I should have just built a masonry chimney.

My situation is very similar to Clinton County's--I burned wood in a QuadraFire for several years before thankfully switching to coal 4-5 years ago. I have the coal-rated SS liner and have always wondered how I would know if I had a degraded liner from coal acid. Also, I wondered what difference it would make given the double-walled liner is placed inside a terra cotta flue pipe. I clean my chimney each spring just after heating season, have a cap on the chimney, and thoroughly clean stove and put rust inhibitor and Damp Rid inside. Your thoughts please! Thanks!

I ran a Metalbestos 20 foot chimney with a cap for about 4 years with a couple of different hand fed stoves at our previous house. At the beginning of the season and at the end of the season I ran it really hot a couple of days burning wood. At the end of the season I pulled the single wall black from the stove to the through the wall thimble and stored it open on both ends. Then I pulled the lower plug and dumped any ash accumulated in the bottom. I capped the thimble and left the lower plug open. It was an external chimney so my rational was the summer sun would heat it up and I would get natural circulation through it. Seems to have worked just fine.

It's not shiny but it ain't eaten up either. I have it stored in the garage until I can tear down the coal ash block and terra cotta lined chimney in the kitchen and I'll put it up there.

JohnB wrote:

VigIIPeaBurner wrote: Dumping it down a masonry chimney doesn't carry the negative possibilities like doing and incomplete neutralization inside a SS Dura-Vent could.

So what is a better solution? Doing nothing?

Doing nothing is akin to never changing the oil in your car and waiting until the tires go flat. A little Preventative Maintenance is always better than doing nothing.

Rev. Larry

That's my thought exactly. I burn wood at the beginning & end of the season which should help but I'll stick to my plan to sweep it out at the end of the burning season.

Stuff a towel around the nozzle of a shop vac in the clean out door, or chimney top.
Hook the hose up to the outlet side.
Put the Arm and Hammer in the vac and turn it on.

That should fog out the chimney the same way the ash does.

Paul

Mixing water with a little baking soda and dumping it down the chimney is like putting a little sand in with your fresh oil change to scrape out some of the carbon in your engine. Your never going to ensure every part of that mix is going to hit every part of the chimney ... and the parts you missed just turned to sulfuric acid.

Tried that with my stainless pipe. All it did was accelerate the rust, and cause discoloration on the outside where it dripped.

I'd just run a DRY brush down it, make sure it's capped, and hope for the best. Best course of action would be SCRAP IT and build a MASONRY chimney that will out-live any of us.
My stainless pipe, third season:

Biting the Bullet,Smitty's put the Truth out there. Sure,it's going to hurt,but done right,it's done for good.

I have 2 masonry chimneys, both go up inside my house, 1 has out lived everyone on this planet 3 times over & neither is usable without a stainless liner which they've both had inside for the past 25 years. It's already cheaper for me to burn wood so I'm sure as hell not going to spend money on a 3rd chimney tacked onto some outside wall. If I'm still burning coal in 10 years I'll let you know how this works out.

I'm using a brick chimney that was built in the 1890's before the days of liners. Just hooked it in to where the original kitchen coal range was. Still works fine. This house was the local coal dealer and was built to heat with coal "octopus" furnace in the central chimney and coal kitchen range plus coal hot water heater plumbed into the back chimney.

The 8 feet of single wall from the range to chimney is going on 8 years now. Just vacuum it in the fall, and shovel out the fly ash build-up in the bottom of the chimney.

So far, so good.

Paul

Edit. I should add that the chimney had a slate cover closing off the top for all the years it wasn't used. I just raised the slate with a half brick under each corner to make a rain cap.

I'm surprised that the single wall has held up this long. It didn't with my potbelly stove when I lived on long Island south shore, but that's a much damper climate.

Paul

blrman07 wrote:

JohnB wrote: So what is a better solution? Doing nothing?

Doing nothing is akin to never changing the oil in your car and waiting until the tires go flat. A little Preventative Maintenance is always better than doing nothing.

Rev. Larry

Respectfully, your last statement is not universal in application. Nothing ever is. PM done properly fits your analogies. Done improperly, it will haunt your wallet with respect to stainless steel stovepipe or chimney/liner. It might not be better than doing nothing.

Understanding the chemistry of what occurs when and how the baking soda is applied is where it starts- ions have to move to react. Here's another analogy. Look at it like a battle for a wall. One side waits on the wall for the approaching enemy. Nothing is happening until the enemy advances on the wall. Then the carnage starts and whatever happens, the wall won't be the same as before. If there are enough enemy troops, the wall will be destroyed. If the the number of troops are evenly matched, both sides lose some members and it's a draw (neutralized). In the end whoever wins, the wall is weaker than what it was before. It's similar to what happens during the battery terminal cleaning example dustyashpan's posted above, that "clean like new" terminal clamp is thinner than it was when new.

Applying dry baking soda doesn't neutralize much ash. It won't do much chemically without water being present - like the troops on either side of the wall before the battle started. For the neutralization to occur, water is the facilitator (the advance on the wall). The ions in the soda and ash don't move far or fast without water. Therefore, there's little to no acidic corrosion to the metal surface nor any neutralizing activity from the baking soda (the troops are just looking at each other across the wall). Mix the baking soda with water, apply it to a metal surface with ash present and that's when both reactions start moving faster (the attack begins). Understand that the mixture is baking soda AND water - it doesn't change into anything different. It makes the baking soda more active as a neutralizer and when the water in that baking soda mixture wets the ash, the ash becomes more active as an acid. While the baking soda and ash acid are battling it out (the attack), the acid is simultaneously working on the metal surface (the wall). If there isn't enough baking soda present in the water to neutralize the ash/acid, the metal will suffer more than it did before the soda water solution was added.

Of course, while I was droning on on the keyboard, Smitty said it quicker and more clearly

Rather then add water,. . . . wouldn't dusting or fogging the chimney help as the moisture (vapor pressure) of warmer months works it's way into the chimney and gets absorbed by both the ash and the baking soda ?

If the moisture level stays low, then nothings lost, right ?

Paul

Sunny Boy wrote:Rather then add water,. . . . wouldn't dusting or fogging the chimney help as the moisture (vapor pressure) of warmer months works it's way into the chimney and gets absorbed by both the ash and the baking soda ?

If the moisture level stays low, then nothings lost, right ?

Paul

Indeed! Tried to address the application of dry baking soda that in the third paragraph of my above post. With this approach is it's not going to be applied uniformly if it sticks at all in many places. If it does stick, will it be enough? If it makes you feel like you're doing something positive/preventative, then dry can't hurt, it just might not help. Kinda like facing a running fan and turning a hose on it - some parts of you will stay dry

• Point of all this is ...
  • keep your powder dry

So far, I haven't seen a need to do anything, . . . other then vac out the dust and keep out the rain. And this is just based (chemist pun intended) on 8 years of using a coal stove here. I know that approach would not work back in my really damp Long Island house.


My preferred use of baking soda is mixed with water and drink it about an hour after I had to eat my own cooking !

Paul

The biggest problem in this discussion is that the majority of the corrosion happening inside a chimney is not occurring during the summer months, but rather as the stove is running. As the flue gases move up the chimney, there comes a point where they drop in temperature to below the dew point and that is where liquid condensation occurs. The fuel used carries various constituents, for example sulfur, which that constituent drops out as sulfuric acid. The flue gases always carry water, for two reasons, one is it's a by-product of combustion and second it's in the air being fed into the stove for combustion to occur. The issue is not so much what happens after the season, but rather during the season of burning.

dj

Ok newbie question here....If you have a terra cotta lined chimney does burning coal affect it at all? How about the mortar?