The Steamboating Forum

I'm in the process of building an Ofeldt boiler. The center column is schedule 80 6" pipe. The coils are 1/2 tube coiled into 6" coils about 10" long. My question is where should the sight glass be located. Should the top be a little higher than the top of the coils. Should the water level be higher than the top of the coils? My sight glass is about 8" long and it's one of those that uses a thick, flat glass.

Hi Pat,

Wise boiler choice. I really like the Ofeldt.

On my Ofeldt the sight glass Which is only about 5" readable range, is mounted About 2" from the bottom of the boiler for the lower fitting and 6" from the top on the second fitting. My center drum is only 14" tall. The water level on an Ofeldt is a bit more difficult to read because when firing much of the water is in the generation tubes. Anyways, coupled with the short readable length, my sight glass is about two feet away from the boiler, but it still reads somewhat accurate. If I make a right turn, there is no water in the glass, and a left turn it comes back lol.. On a straight away is the only time it is really accurate and it does pretty good.

A note on that type boiler. Carry over can be an issue if the center drum is very short. Some sort of deflector and steam dome/separator needs to be used inside. The water and steam sprays out of the generation tubes. A superheater is a good thing to have as well to handle carry over, plus give it some extra kick.

-Ron

Perfect! Thanks. While I don't have a set of plans, I'm using the info about your build for pointers. A super heater and preheater are in the works. I am planing a baffle and my center pipe is going to be L O N G.

My Loon Valley-style boiler steams better with the water level high... you can prob. split the difference - half the gauge above and half below the top of the tubes.

- Bart

Another thing I forgot to mention.

On the Ofeldt, the center drum/reservoir is a downcomer too. Water circulates up the tubes and back down through the middle. They have excellent internal circulation. So it may be a good idea to attach some sort of deflector on the bottom of the drum to deflect direct heat. Otherwise the water may get mixed up on which way to go.

I mentioned how my sight glass is but didn't really say how it is used or maintained. I try to keep the water somewhere near the top of the glass.

-Ron

Since I plan on firing with coal I have planned a circular stainless steel disc a tad bigger than the center drum to be mounted about an inch from the bottom of the drum to deflect the heat. In other words, no direct heat will be directly on the drum bottom.

Yep, that is what I would do if firing wood or coal. We copied the Ofeldt kerosene burner and couldn't figure out why it had a center drum like the boiler and emitted no flame in that area, then we finally figured it out. Them guys were really sharp back then.

-Ron

I find it both entertaining and frustrating to have people come into my shop with what they think is some revolutionary improvement to small steam plants. I usually let them down easy but the bottom line is that this has all been beaten to death over a hundred years ago.

On the other hand, here is a new animation of how Gresley valve gear works! Turn up your sound.

http://www.newportharbor.us/computerworks.htm

There seems to be a common misconception occasionally when people become interested in steam that there are lots of stones to still overturn and with what we have nowadays, we can do much better. They fail to realize the number of people that are actively working with steam development presently is miniscule in comparison to a hundred years ago. They also somehow believe we are much smarter now. I copied a whole car from a hundred years ago. The most significant thing I learned was that the people that designed it were hard working and very intelligent. They didn't miss anything. All one needs to do is study the White or Doble steam car. They were engineering masterpieces. White did it all- automatic everything with no electricity.

They eventually realize that even with modern materials, design programs and microprocessors, no real gains are to be had.

When Richard Trevethik went to high pressure steam and George Stephenson designed the standard in steam valve design, the course was set and has not deviated much. It seems every time someone tries, the gain in one part of the plant represents a loss in some other part.

-Ron

While there may not be a lot of stones left to overturn, we would do ourselves a disservice to confine ourselves to the steam engine designs from before 1900. Yes, a single cylinder counterflow is a classic piece of machinery - but that's no reason to be satisfied with a steam consumption of 30 or 40 lbs/hp-hr. Small marine steam engines were obsolete as power sources much earlier than larger ones, so we don't have a very complete historical sample of more efficient small engines - but this doesn't mean they aren't possible. Yes, w/ a small boat and free (wood) fuel, it doesn't make a lot of difference, but the engineer in me is intrigued with poppet values, uniflow engines and the like. High circulation boilers (whether natural or forced) are also interesting.

- Bart