Hot water zone off steam boiler

michael_15

How does boiler sizing come into play when piping a hot water zone off of a steam boiler? For example, if I have 160sqft of attached radiation and a lot of extra piping, bringing me to:

160 sqft * 240 BTU/sqft * 1.5 pickup = 57600 BTU

then 57600 BTU output would be the size of my ideal steam boiler.

What happens if I add a hot water zone? I'd like to heat a small unheated area which for various reasons contractors have told me would be extremely hard to bring steam piping into, which made me think hot water. I know nothing about hot water right now, unfortunately.

I've got unheated space with, say, 20,000 BTU heat loss on a design day (I haven't done the math, but it's about as energy-efficient as a milk crate) and was hoping to get some cast-iron radiators to heat it (new or used, doesn't matter). Unfortunately, this sounds to me like 120 square feet of radiation, which is an awful lot of radiator.

Anyway, what does this do to my ideal boiler size? Does it add 20,000 BTU off the top, meaning my boiler would be ideally 57600 + 20000 = 77600 BTU output? Is there an additional "pickup factor" for hot water? Or does the hot water usage actually eat into the pickup factor for steam, hence not requiring a 20,0000 BTU larger boiler?

-Michael

Unknown

Here's the scoop, two times

http://www.heatinghelp.com/newsletter.cfm?Id=29

http://trainingroom.slantfin.com/articles/nm0304-1.html

Noel

michael_15

Thanks,

It seems from the first link that in fact I don't need a bigger boiler at all, so long as my hot water zone is enveloped within the pickup factor of my steam system... is that correct?

As to the second link, well, I sure hope the professional I'm going to hire already knows all of that, because I certainly don't, even after reading it!

-Michael

Unknown

I wrote the second one

He can call me at 800 873 4346 if he likes, 9-5 Eastern time.

Noel