Not venting drip returns

gfrbrookline

I have a large brick apartment building that is built on a hill in Boston. My one pipe steam system has two mains front and back, with two drip or step returns to drain the step up elbows in the mains.

I have always vented the drip returns thinking more venting is always better and that is the way it was the I bought the place. I was advised years ago not to do so by @Steamhead and others but didn't listen. I don't know why but this year something clicked and I figured I would give it a try and removed the vents from the drip lines and plugged the fitting. I still have one drip return that gets warm, but the high side of the building now heats much faster 3-5 minutes and my operating pressure runs lower.

Bottom line more venting is better if it is in the right place and listen to the advice of the masters on the forum.

mattmia2

A drip doesn't need steam in it. A vent will let the drip fill with steam up to the vent. Without the vent the air will not be able to get out of the drip and it will be filled with a column of air which will keep the steam from colliding with the water in the return.

gfrbrookline

And that is the lesson I have finally learned/figure out after all these years of thinking the more venting the better and that if I vented the drips it would heat up the lower side faster and close the vents so steam could reach the upper side faster. As it turned out not venting the drips let steam reach the upper side faster or better stated at approximately the same time as the lower side of the building. Hopefully I will see an improvement in the gas bill this year.

JUGHNE

Could you post some pictures of this situation?

I can't see it in my head.

gfrbrookline

I have two of these joints. It is a drain off of a 90 degree riser off the the main.

gfrbrookline

perhaps I am not using the correct terminology.

JUGHNE

So that drip connects to a F&T or thermostatic trap on the other side of the wall?

And then connects to a dry return vented thru a cond or feeder pump?

Where did you have the air vents?

gfrbrookline

No, one pipe steam, the drip returns drain on gravity into the Hartford loop with the main drain, no traps or pump.

gfrbrookline

https://us.v-cdn.net/5021738/uploads/editor/pl/ct40rfm0dqkn.jpg


The riser goes up about six feet and then the main continues horizontally another 20 feet along the upper section of the building. Hope this clarifies.

JUGHNE

So air venting is done on the steam main itself and also rad vents.
Thanks.

gfrbrookline

Yes, the rads are vented according to the gerry gill chart and the building is now heated evenly and quiet. It took me years of trial and error to get to this point.

Steamhead

@gfrbrookline , was that one of the buildings I flew up there to look at maybe 10 years ago?

EBEBRATT-Ed

I must be dumb. I don't see venting the drips having any effect good or bad. Mybe someone can explain

gfrbrookline

@Steamhead I wish you could have come up and look at my building but your advice, @New England SteamWorks servicing and making modifications and my tinkering my boiler is running like a Rolex.

This forum is a great resource for those of us who have steam and are willing to understand the limitations of our local contractors and take projects on ourselves.

mattmia2

Where did you have the vents in the drips?

gfrbrookline

Right before they dropped down to join up with the Hartford loop, same place as the returns from the mains. You can see the plugged pipe in this pic, there is another one in the pipe to the left of it.

gfrbrookline

My boiler is a bit of a beast as it also feeds two 80 gal indirect superstores and a hot water loop to a basement unit. The 3 1/2 header is a work of art that keeps the steam nice and dry.

mattmia2

with the drip vented it means the steam follows the main and the drip from the point of the drip, it has to heat both to get to the end of the main.

gfrbrookline

If I plug the drips it directs the steam up the steps in the mains, as pictured previously, and let the steam reach the radiators on the high side of the building faster. If the drips are vented the steam will fill the drip returns in the basement before going to the high side of the building, lost art of steam, steam finds the path of least resistance. The radiator vents offer more resistance than a main vent so if the drips are vented with main vents the steam is going to go in the wrong direction until the main vent closes on the drip and then redirect up to the radiators. It is like someone entering an exit ramp on a highway hitting a road block and then doing a u turn to go in the right direction.

gfrbrookline

The drip returns are there to allow the condensate to return to the boiler and avoid banging in the pipes in an ideal world they should never see steam.