Modular steam boilers

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Modular steam boilers

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Jazzerman

Excellent article. Very good information and explanation of why certain piping details are important.

cgdelzell

does this article apply to ounces twinned steam boilers? since they have a very low pressure.

vaporvac

That pic looks very familiar; I studied it long and hard when designing my system. @cgdelzell , I'm not a pro, but would say the same rules apply as my system is a twinned vapor vacuum. It is a gravity return with NO condensate tank, but only one equalizer for both boilers per Slantfin's instructions.

nicholas bonham-carter

I think JStar had success with the use of a Giford loop, and gravity return, as the means of preventing any excessive water level change in the off boiler. As a result, no electric valves were needed in supply or return.--NBC

SeanBeans

Thanks for the added knowledge Dan!

RayWohlfarth

I love using modular steam systems. One of the things I consider when using modular steam is the control strategy. You cannot control it like a hydronic system. I like to use the analogy of an airplane taking off to describe modular steam boiler control. The airplane will use full power to take off and once they reach cruising altitude, the pilot reduces the power. Do the same with steam. Start all the boilers to generate steam pressure. Once you start generating steam pressure, you can stage the boilers back. If you start only one boiler at a time, it will operate and never build steam pressure.

Mad Dog_2

Very well explained Dr. Holohan. Thank you. Mad Dog

kremer_robert

Dr. Holohan,
Your write up is a big help to any boiler man and you should write a textbook .
Can you recommend a steam boiler setup with modular boilers 3-8 (about 100 horse each low pressure) that can pass a 36" door for commercial applications.
I am thanking you in advance of your steam wisdom.

Robert

RayWohlfarth

Robert I would look at either Superior boiler They bought the Triad line or Hurst boiler

DanHolohan

Thanks, Robert. I did write a textbook: https://heatinghelp.com/store/detail/the-lost-art-of-steam-heating-revisited

TanklessDR

Wow!! excellent piping details.. Thank you!! It's worth the read!!

jumper

RayWohlfarth said:

I Start all the boilers to generate steam pressure. Once you start generating steam pressure, you can stage the boilers back. If you start only one boiler at a time, it will operate and never build steam pressure.

Same for multistage burners?

The Steam Whisperer

Hmmm, that install looks familiar...I didn't know we had made it into one of Dan's Articles! Just as an FYI, those boilers are piped with a common header and return per Slantfin When first installed the waterlines are pretty wild, but once things get cleaned up they settle down nicely. Slant fin seems to have figured this piping out pretty well. That Heating plant is feeding a 10 to 12,000 sq ft home with an old vapor system that was upgraded with orifice plates to eliminate the need for the steam traps and allow the boilers to be stage fired off a two stage thermostat. Only a single 200,000 input module runs, except for a couple days a year in extreme weather, and it supports about 1800 sq ft of radiation on a single zone. In fact, now that the insulation has been upgraded, the owner just valves off the second boiler and turns it on manually, instead of the two stage thermostat turning it on. The boilers are being fired with Heatwise Su-3 burners... incredibly loud, but can be turned down to about 1% excess air or less and still burn clean. Too bad Heatwise is gone
Been going to 8 years and only one issue... gas usage apparently was so low that the gas company came out 2 years in a row to check the metering equipment... and this was before insulating occurred!

DanHolohan

Thanks, Dave. I pulled the pic off The Wall. It’s perfect, as always.