Draft

[Steamboat Mike]

Tim, some other thoughts, are your tubes really, really clean? This can affect operation in two ways that I know of. First, soot and char are very good heat insulators, read what Frank Graham says about soot in Audel's Marine Steam Engineering. I have found that brushing alone really doesn't get tubes sparkling clean, ask your dentist, you really need to floss. To floss tubes you need a tube scraper. I use one from McMaster-Carr, catalog number 7085T41. Your tubes are the same size as mine so this will work for you. Use a wire tube brush then put a light in the firebox and look at the tubes. Use the scraper and see how much more soot comes out and how the tubes will actually shine, that is if they are not rusty. Getting the tubes scraped makes a big difference in Catawissa, the fire roars on natural draft, and as you know I have a fairly short stack. The gunk seems to have a big effect on the flow of gasses. When I clean the flue for our wood stove the draw is so much better, no smoke spilling into the room. One last thought, I seem to remember from somewhere that the gain in draft per foot of added height is not all that great, especially when you consider that you are starting with a a a very small value in the first place. I think that is why old factory chimneys were so tall.

That's all for now, happy steaming dreaming till spring.

Best regards, Steamboat Mike

[swedtug]

I agree, soot is no good.
last year I got the bright idea to throw in a rubber boot in the fire, It was lots off black smoke, but after a while I started to lose pressure, at first I did not understand what the error was, but when the fire began to burn out of the fire door I understood.
I was still a test drive so I had no soot brush or steam Lance with me .
It took me many hours to take me home, with maybe a knots at best, and many hours in sooting the day after.

I learned my lesson, no rubber in the boiler. and a steam Lance is a handy thing to have.
.

[DetroiTug]

One consideration on tall stacks used in the past and the reason for their height other than increased draft, was probably to keep the coal smoke high enough so folks didn't have to breathe it or as much of it. I ran coal on the Tug (with relatively tall stack) once and on the after deck it was not all that pleasant. Can't imagine working in that all day.

I was reading something somewhere about life in heavily populated areas in the late 1800's and coal smoke was a real issue in the winter months as that is what most people used for heat.

-Ron

[Mike Rometer]

It was in many major cities right up till the start of the 1960s. London in particular would be cloaked in fog and the smoke couldn't get above it so mixed with it to become smog, killed loads of people with poor respiratory systems every year.

[Steamboat Mike]

Tim, yet another thought, I hope not the last. Is your stack insulated? Some designs have an air space between the inner flue liner and the outer jacket. This is intended to keep the jacket cool enough to avoid scorched paint and burns (boiler bites). It has a negative effect on draft. The better design is to use an efficient insulation, I use 3/4" of Kaowool, to keep the chimney gasses as warm as possible to keep the density and temperature difference as great as possible between inside and outside so the column of gasses continues to rise.
Best regards, Steamboat Mike

[smokestackmag]

Steamboat Mike,

No, My stack is not insulated. I think the only way that could happen is if I make a liner and slide it inside along with the insulation. I'll do an insulated stack on boat #2, coming soon, I hope.

[Lopez Mike]

My stack is 8" by 6'. If I slide in a 7.5" liner with insulation around it will I gain enough to offset the reduction in diameter?
Wood fired VFT-30.

Thoughts?

Mike

[smokestackmag]

And, friends, is the question of the day, echoed by me.

[Steamboat Mike]

I think the answer to the question of the day is a qualified "yes". Well, it worked for me, your results may vary.
I try to change one variable at a time to have at least a good guess at what change resulted in what improvement, or not improvement.
My experience with airtight wood stoves has been that bigger is not necessarily better. A surprising volume of air and burned gasses can be moved through a remarkably small pipe. It seems counterintuitive but a 7" pipe may well draft better than a 9",velocity seems to be better in the smaller pipe. One stove manufacturer specifies a 6" pipe even for a 45 foot vertical run, something about the gasses cooling and slowing more in the big pipe, seems wrong to me, but the stove sure draws well.
Back to the drafting table, best regards, Steamboat Mike (Catawissa)

[smokestackmag]

Steamboat Mike,

Sounds like a plan, after other, more pressing, items have been completed. And for me it's actually quite easy to do and won't affect the outward appearance at all.