How much pipe pitch?

1887steam

I have a long horizontal pipe (8 feet) from the top of the riser to the radiator (the farthest radiator from the boiler on the top floor). Is there a general rule of thumb regarding how much pitch for such pipe and radiators themselves?



I have had trouble getting steam to these last radiators and increased that pipe size from 1-1/4" to 1-1/2" coming off a two inch riser (with a cross T to two sides) and used 45 degree fittings all to make it easier to get steam to the radiators (was this over-kill?). Gorton #2 vent at top of riser & 3 gorton #2's at the end of the main where this riser starts. Vaporstat cut out at 10 oz, cut in at 5 oz.

FJL

Amount of Pitch

In a counter flow system, the ideal pitch is one inch per foot.  I found this information on this web site:



In a one-pipe steam system, the condensate and the steam have to pass

each other in that horizontal runout to the riser. If the riser feeds a

radiator on the first floor, the pitch is not so critical because

there's usually not that much condensate flowing back. However, when the

riser feeds an upper floor (and you can't drip it) you have the

additional burden of the piping to consider. A lot of condensate is

going to be fighting that steam on its way to the radiator. To avoid

water hammer and uneven heating, you should give that runout to the

riser a pitch of at least one-inch per foot. Use a line level to check

it."



If you can't give it that much, give it as much as you can, but no less than 1/4 inch per foot, at least that is what Noel Murdough was kind of enough to tell me in an email exchange I had with him a few years ago about this same issue.

JamesC in Stamford CT

amount of pitch

I also have a one-pipe stem system, but with a wet return. Some piping replacemnts over the garage doors in the cellar were done before I bought the house, and the pitch is lacking in that part of the main. You can see in the attached diagram of my system that it's kinda a counterflow, in that up to the point I have labeled "inflection", the main is sloped back to the boiler. And after that point, it slopes the other way, since after that point the condensed steam will find it's way to the returns.



From the boiler to the point of inflection, as the pipe goes over the garage doors, the pipe is hardly pitched. So, for that part of the run, what is the optimal (and minimal) pitch I should be shooting for?



Thanks,

James