Quick, stupid steam question

Unknown

In chapter six of Dans "Lost art of Steam heating" He talks about under or over firing a steam boiler.

I understand the results of both, but im a little confused in the semantics in regards to overfiring.

I size my replacement boiler to the EDR of the building and use either the 1.33 or 1.5 pickup factor and select my boiler to fit the load.

Lets say I choose a boiler thats load matches mine, and the maximum firing rate of said boiler is 1.00 gph (oil) I am assuming that the only nozzle size I should ever fire in this boiler is 1.00. When Dan talks about over firing, I would we over firing if I fired anything higher than 1.00 for that boiler.

Is that correct?

Sorry for the stupid question. Trying to learn more about steam.


Norm Harvey,
Independent Burner Service,
Weymouth, MA

JLK

While someone is answering the oil nozzle question would you commment on the same question except for gas boilers? How do you over or under fire a gas burner unless you replace the orifices installed at the factory or drill them out. Or does he refer to undersizing or oversizing t he boiler. Was it semantics, misprint or hidden stimulation for a discussion??:)

Steamhead (in transit)

What he's saying there

is you have to make just enough steam to heat the system. If your boiler or burner is undersized, you won't make enough steam and the system won't heat all the way. If you make too much steam, it will short-cycle and in extreme cases overcome the "A" or "B" dimension.

To which I'll add- if you fire a boiler at a higher rate than it was designed for, you'll probably throw a lot of water up into the system which can cause banging. You could also generate a lot of carbon monoxide and/or crack the boiler.

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Dan_22

Are you saying the velocity of the steam exiting the boiler will increase if the boiler input is increased. I dont really understand why the exit velocity would increase if the load of the system does not change. My guess would be it would build pressure quicker which would actually cause a decrease in velocity.

Steamhead (in transit)

At start-up

the velocity is greatest since there is no steam in the system. If the boiler is overfired, the velocity at start-up will increase.

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Dan_22

Thanks for the answer. Could you take a look at my post "steam engineering question" and let me know what you think?

Steamhead (in transit)

That's process steam

which I don't have much experience with- maybe one of the other Wallies will pick that thread up. Two pounds is my limit ;-)

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