Steam pipe size

bobbob

One-pipe system. Coal converted to NG. My pipe sizes are off from what Dan says they should be. My mains are 1-1/2". I think Dan said 2" minimum. Sounds like my system should not even work, but somehow it does. Put a 0-5 guage on it. goes up to two marks, so that is 3.2 ounces max. Pressuretrol never shuts cycle off, the thermostat does. All radiators heat up totally or at least down to the last section, except the long squat one that runs in front of the double windows in front room. When we had colder weather it would fully heat up after I drilled it out for an extra vent. O, I ain't complainin! Looks like sometimes things defy sound logic and just work anyway. Is that common?

KC_Jones

@gerry gill once commented that there are systems that violate the rules.  His deduction was that as long as the system used all the same pipe sizing charts it should work, even if it didn’t follow classic sizing methods.

My system violates most of the rules.

2” mains reduced to 1 1/2” in the horizontal.
1 1/4” takeoffs for all first floor, as high as 60 EDR
1” takeoffs for all second floor, as high as 40 EDR
All takeoffs from top at 90, not 45.
And the final detail, I’m barely radiated enough maybe even slightly under, for the heatloss.  On the coldest days my radiators can stay fully hot for days on end and on some rare bitter days (below design) the indoor temp may drop 1 degree from set point.

My system is silent, heats evenly, and never goes above 1 ounce of pressure.  With all its faults, I love it.

EBEBRATT-Ed

@bobbob

Depends on the pitch of the pipe more pitch removes condensate rapidly, less condensate more steam can flow. And how well the pipe is insulated, more insulation and in a warm enviroment less condensater will form.

Not having the pressure control trip is good

SteamingatMohawk

What are the ratings on the boiler label? If the boiler is small, those sizes may not be an issue, which I suspect is the case, since the performance (mentioned in this discussion and the other one) seems to be right on. How large is the house?

ChrisJ

How many mains do you have?
What is the size of the boiler?

bobbob

ChrisJ --House outside dimensions 27 X 36, two story brick, 12 cast iron radiators of various sizes.
Built in 1900.
boiler tag reads:
net I.B.R. Ratings 1060 hand fired, 990 stoker fired, 990 oil fired. Firing rate oil 2.25 gals/hr. Firing rate stoked 26 lbs /hour
It is a Crane 20 made for coal or oil. May have originally been coal fired, or perhaps oil. Was oil used by 1900? Was converted to NG at some point.
My boiler has one head pipe that tees off to left and to right. My mains are 1-1/2", which Dan Holohan says should be a minimum of 2" for one-pipe. Risers are 1-1/4", and tee off at 45 degrees.
The really strange thing about my system is that the mains make a long loop around the basement that is all connected, One side goes off the left side of header, the other to the right. The returns drop down right at the boiler. Pitch of pipes is correct to drain condensate. The highest point of the Main Loop is the southwest corner, so condensate is drained both directions back to either the left or right side of the boiler. This setup leaves me scratching my head as to where to place main vents. I recently finished insulating everything--a rather expensive and time consuming task.
Dan Holohan prescribes ALOT of main venting near the ends of the mains, but I don't have any ends.
Somehow my system works surprisingly well, but I am just wanting to make sure it is as efficient as possible.

SO, would one install main vents at intervals all around the main loop?
Thanks for everyone's help!

KC_Jones

"The returns drop down right at the boiler."

That's technically the end or your mains, but most consider the last radiator take off to be the end. In your case, perhaps both of those are in the same location?

Pictures might help with that, but from your description it doesn't sound like an unusual setup. I have something similar in my house as the "returns" are overhead for most of the run and don't drop to the wet return until right at the boiler. My entire wet return is about 2' long.