FWL

J.C.A._3

Steamhead has the answer. There is pressure getting into the returns from somewhere. Your quest is to find out where AND how....then correct the problem.

FWL is a great way to deal with sizing a boiler properly,(Smaller is always better but won't fit with the piping scheme) but you've got think like water...and steam when doing it. The path of least resistance will be the way both will go. Both water(condensate) and steam will go the easiest way possible to get back to the system, their ultimate goal!

Think outside the box for a bit...Reason out where the steam is holding the condensate from getting back to its base...and work from there. Pressure is the enemy...Work at figuring where it's higher than it has to be and the problem will be solved.(usually the return getting fed steam pressure from somewhere it isn't supposed to be is the culprit). Look for bad traps and poor or inadequate venting. Chris

John S.

I think I need one...

I recently checked and repaired the pitch of all the dry returns on an old Webster Modulation system. The NOWL is now significantly lower than when the boiler was installed and now the highest points of the wet returns are filling with steam which would normally be travelling through the runouts.

There are three Webster vent traps in the building at the end of the three dry return mains. My question is... Does a FWL have to be constructed at all three dry return ends? Or could I get away with one FWL at the dry return that comes back in the boiler room?

It's not the first time when working on this system that my 'fix' has caused other problems. That seems to be how it goes with an old steam system that's been neglected for years.

Any help is much appreciated.

Steamhead (in transit)

You only need one

and that one should be in the boiler room, where all the wet returns come together. This way it will raise the level in all of them.

But if the steam only gets a couple feet down the drip to the wet return, that isn't a problem.

John S.

Steamhead

It's not that the steam is making it far enough to cause a problem in the return system, however, it seems the rads are not heating nearly as quickly as they did prior to my re-pitch work. That's what confuses me.

I need to take some apartment temeratures to get a feel for what's happenning but don't want to run the gas bill up testing in this mild outdoor temp (did enough of that last year.

What may have happenned... a sagging main dry return may not have been letting any air out after a certain point. Now that I have dripped the sag, maybe that 1/3 of the system is robbing the other 2/3 from air removal?

Is it possible that I'm overventing the dry returns?
There are currently 7 Gorton #2s venting the two steam mains and on the dry returns (consisting of three vent traps) there's a total of 12 Hoffman #75s.

Can a FWL be constructed from the wet return?

Steamhead (in transit)

I'd first check

to see if any steam is getting into the dry return. This will pressurize it and the steam won't flow into the rads as it should.

When you say "vent traps" do you mean crossover radiator traps from the steam main to the dry return? If so, make sure they're not blowing steam into the dry return.

John S.

Steam is not getting into the dry returns.

The vent traps I'm referring to are the big cast iron monsters at the end of the dry returns. I built a manifold to hold a bunch of air vents. The pic was taken before the manifold was built.