one pipe steam system - pipe size question

T-O

On a one pipe steam system, looking at he "pipe sizes - one pipe system chart", I have two questions:
1- what is the proper pipe size needed for a 15 foot horizontal branch(non-dripped) attached to a riser feeding 3 radiators, 50 EDR each, one on each floor of a 3 story building
2- What is the maximum number of radiators at 50 EDR each, that can be connected to a 1-1/4 riser?
Please based your input on the information given and the one pipe steam system pipe sizes chart. Thanks

Brad White_29

I may not have the same chart you refer to

but this is what I come up with:

The Horizontal: 2" (I consider that a minimum default size for more than two radiators; It really is a main, IMHO). Your stated lenght of 15 feet does not enter into it.

(BTW: If it is non-dripped, may I assume it is pitched back to the boiler or originating main properly?)

How many 50 EDR radiators per 1.25" riser? One.

You may think it is "close" to two, being 98 EDR connected but I would not push it. Pipe counts as radiator especially if not insulated. I would not push it. Also each radiator tapping at 1.25" size is adequate for 62 EDR as a point of reference.

The risers for each radiator I would have at 1.25" and if I had my druthers, the 3rd floor riser I would make at 1.5" on account of height and if offset on the way up.

Some subjective interpretation but that is what I would do.

T-O

Thanks for your good input. Yes, the none dripped horizontal branch is properly pitched back to the main. As a note a 2" horizontal branch (not dripped) has 169 sq. ft. capacity if up to 8 feet long and 93 sq. ft. up to 8 to 12 feet long.