#'s of steam radiators

NHPluminator

Hi..
im new here, so anyways ...i have been in the plumbing and heating field mmm like 18 years and never do alot with steam heat, .. so my question is is there a limit on how many steam radiators will run off a 11/4" branch off a single pipe steam loop?.. i havent changed the firing rate of the burner yet ...i have checked ..pitch, vents , and even put in a condensate return run...it did help with noise..btw... but still they heat like a slug and such..the funny thing is the other 2 on that loop heat fine , and yes i have adjusted the vents down on those ...

i ask because i recently installed 2 more to a new room
and well... it's being a pain , one heated fine , the other only the first 2 sections <--- and make's a slight girgle sound....i attached a pic of the loop... any ideas would help thanks..

DanHolohan

With one-pipe steam

you shouldn't go smaller than 2" on any horizontal main feeding radiation. You should get a copy of The Golden Rules of Hydronic Heating

Paul Mitchell_2

Not that many most likely

You need to first establish the total EDR of the radiators. Then you can see if the 1 1/4 pipe will handle it. You are going to most likely have too much iron on that run. Also as you add iron to the system you change the boiler size needed. Firing rate is not usually the answer. Especially if you are thinking of firing the boiler above its rated max.

DanHolohan

Paul,

none of the Dead Men books recommend running horizontal steam mains in one-pipe systems smaller than 2".

Steamhead

First thing to do

is see how much radiation is on that sluggish loop. Then we can determine what pipe size is needed. I agree with Dan, it should be at least 2-inch.

Also, does this branch loop pitch up from the 2-inch main, or down from the main to a drip?

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NHPluminator

# radiators

there are four rad's on it now ..aprox size 4' tall and 5 sections each..

and it pitch's up..from main..

Steamhead

They probably total about 100 square feet EDR

which is too big for an 1-1/4" pipe. This amount of radiation requires at least 1-1/2". The above assumes 3-column or 5-large-tube radiators about 38 inches high.

Further reducing the pipe's capacity is the fact that it pitches up from the main. The steam and condensate have to keep out of each other's way since they flow in opposite directions. You need a main one size larger with this Counter-flow setup.

You need to repipe the branch main as far as the tee feeding the last 2 radiators in 2-inch pipe. Also add a 2x3/4" tee near that last tee to install a main vent. And make sure the boiler and steam main can handle the additional load.

What size pipe runs from the branch main to each of the radiators on that main?

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NHPluminator

the main run is 2" and the rad branches off that are 1 1/4"
the exsisting run im working with is 1 1/4" so i ran 1 1/4" but im going to up size the exsisting horizontal to 2 " and the 2 runs to the new rads i installed to 2 "
..after the holidays

Steamhead

That should work OK

2-inch as far as the radiator runouts and 1-1/4" for the individual runouts matches the rest of the system. As long as there is not more than 386 square feet of radiation on the main 2-inch line, and the boiler has enough capacity, you should be OK.

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