1 Pipe Steam. 1\" Runout To 2\" Riser

Tom_22

Does this sound normal? On a one pipe steam system I have a riser pipe running up through the first and second floor bathrooms with no radiators per se. Apparently the pipe itself is the radiator. The riser is 2" but the runout from the main in the basement to the riser is only 1". The runout has 2 45 ells and 2 90 ells in it. It also doesn't seem to have much pitch by eyeball although I didn't try to measure the pitch more accurately yet. This pipe gets some hammer usually in mid-cycle, and it makes a lot of gurgling noise. Hammer is much less since reducing pressure on system from about 3psi to about .75psi. Differential before and after: 1 psi.

Is the small runout pipe size an unwise idea?

bob young

THAT IS the way it has been done since day one. if the horizontal is pitched correctly and it is a short run it should be fine. longer runouts might need be increased to 1 1/4 " piping.

Roger Litman

Runout is right

The pipe itself is the radiator and if its EDR is small enough, then the runout is adequate. Read the book and use the equivalent edr of the pipe which is actually just the surface area of the pipe( Pi times the outside diameter times the length) converted into square feet.

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Tim Gardner

Depends on the numbers

There are many things that could cause the hammer, and one possibility is that the run out is too small. However, it could be that the system is dirty, pitch is wrong, etc. Dan's book "The Lost Art of Steam Heating" gives tables and pipe sizes for risers and runouts.

It IS unusual to have a smaller runout than riser. The run outs must be one size longer to carry the same amount of steam as the risers, or two sizes larger if the slope is small. In your case, though, it is not really a riser but rather a radiator, so it is not necessarily a problem. Depends on the numbers.