Venting the steam Mains

Jamie Hall said:

This is two pipe steam? That is, there are two pipes to each radiator (and traps or something of the sort on the outlets?)? If so, part of your problem is that you need a lot more venting on the return. At least one Gorton #2.

And yes, you also need a Gorton #1 where you ask "should there be a vent here?".

This. @BBQ12 , can you post some pics?

OK, where does the line with the Vent-Rite #35 return from?

If there's only one pipe to each radiator, it's pretty well got to be as you say, @EBEBRATT-Ed . In which case, additional venting on it isn't all that important though it surely wouldn't hurt.

But also, if this is single pipe steam with a vent on each radiator, most of the imbalance can be corrected with the proper choice of radiator vents. There still needs to be another main vent where @BBQ12 pointed out.

Start off by seeing what vents you have on each radiator -- you may need slower ones on the ground floor.

BBQ12 said:

The Vent Rite #35 is returning from both the left and right side of basement

So that vent handles the return from two separate mains? Where does the return connect to the mains?

BBQ12 said:

There is no main on left side of basement (top left of diagram)
Do I add a main here?

Yes.

And, if the return that the Vent-Rite #35 is on comes back from where the existing Gortons are, you don't need a vent there. Why fill those returns with steam?

My question again -- how are those "returns" connected at their far ends to the steam mains? Or, to put it another way, are they dry returns, or are they extensions of steam mains? If the latter, they must be go below the boiler water line before they join, or you'll have uneven and erratic heating...

BBQ12 said:

As this is all new to me, how do I tell if they are dry returns or extensions of steam mains?

Trace a steam main. Follow it along its length, starting at the boiler. If it keeps going, without any traps, and keeps going... and comes back as the "return", it's a continuation of the steam main. If, on the other hand, the steam main comes to an end and is connected -- if at all -- to the "return" through a trap, then the odds are good that you have a true dry return.

The distinction is not trivial, nor an exercise in confusing semantics. If it's a steam main or directly connected to one, steam will flow into it (assuming it is vented). Trouble is, if you have two of them the steam will try to come from both directions -- and one way will get to the vent and close it first, at which point the flow of steam in both ends will stop, or nearly so. Now if both ends have already made it to all their attached radiators, maybe not a problem, but if one end hasn't... the poor little radiators will be very slow to heat, since they are depending on their vents alone to allow steam to get to them.

The continuation of the steam main approach is very common, as in parallel flow systems (the mains slope away from the boiler) they allow the condensate in the mains and, in a one pipe system like yours, from the radiators, to keep going along and get back to the boiler.