Properly sizing a \"mixed\" steam system

Kevinj_3

Maybe you get the customers bills from the utility. In our area it is sold by the thousand pounds so you should be able to use that as a check against your ciphering.

Rich L.

How do I size this boiler?

Not sure how many of you are aware of this but my home town, Cedar Rapids, Iowa, went through the worst floods in recorded history a little over a month ago. Our downtown area was inundated with flood waters as well as approximately 4,000 homes. The vast majority of our downtown district was served by "city steam" provided by Iowas (former) oldest continously operating electrical generating plant located just off of the river. This plant was built in the 1880's and has been updated numerous times. I've done some work there in the past and always thought it would make a great horror movie set!

Since the floods the plant has been shut down and the integrity of the city steam lines are questionable. Honestly they were troublesome before this and some think the utility may have been looking for a good reason to abandon them. This is leaving literally hundreds of facilities downtown and beyond looking for heat this winter. We now have many customers looking for heat before winter and this brings me (finally!) to my question!

I'm going to look at a church next week to propose installing a boiler to replace city steam. I know I need to size it to my existing radiation. No problem there. I know from past trips to this church there is a large steam coil in an air handler that serves the sanctuary, as well as radiators. How do I size for the coil? This is all very old stuff so getting info off of name plates isn't likely.

Sorry for the long drawn out dissertation but I thought some of you might enjoy the background of this project.

Thanks in advance for your help, Rich Lorimer

Some flood photos:http://www.alliantenergy.com/docs/groups/public/documents/pub/p016757.hcsp

Steamhead (in transit)

If you can't find anything better

go by the size of the steam pipe feeding the coil. For example:

1-1/4" can handle up to 108 square feet

1-1/2": 168 s.f.

2": 362 s.f.

2-1/2" 528 s.f.

The above figures assume there is no drip in the pipe between the steam main and the coil.

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Rich L.

Thanks

Just for clarification, "The above figures assume there is no drip in the pipe between the steam main and the coil." is referring to drip leg with steam trap, I assume?

Thanks Frank, I appreciate the helpful information.

Steamhead (in transit)

Right

If there is a drip between the main and the coil, and the pipe is pitched from the steam main to the drip, it can carry a bit more steam. This is because the steam and the slight amount of condensate would be flowing in the same direction- away from the steam main.

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