unusual venting situation?

dobro23 · January 2017

just want to ask your opinion on an unusual ( to me) venting situation that i encountered on the job yesterday. we replaced an existing steam boiler with a WM SGO5. most of the house is 1 pipe except possibly 2 radiators. all of the 1 pipe radiators had their vents replaced as well as the main vents. the customer has lived there for 26 years and said that the 2 radiators in question never heated well, if at all. So in trying to describe what is happening, picture this:

the last take off on one of the 2" mains is 1-1/4" that goes to about 10 feet of 1-1/4 steam baseboard. no enclosure and hung about 2 feet from the floor. it is pitched upwards from the supply side. the return end has a 3/4" x 3/4" x 1-1/4" bullheaded tee and the bottom of this tee is a 3/4" iron pipe that goes back and ties into the wet return on the floor in the basement. no steam traps etc and properly pitched. the upper side of the tee was bushed down several times to end up with 1/8" and they had a regular hot water autovent screwed in. i removed all bushings and installed a hoffman 4a since the #75 would look ridiculous. my reasoning was that that particular spur is last on the main and assumed that the radiator would need a vent. but then i wasnt sure because it had it's own condensate return. I am not sure if this main dead ends or continues on to a drop into the wet return. the spur has another section of baseboard on it also piped the same way but wasnt able to locate a vent on it. since the customer said neither ever heated well i figured i must be improving something. no pictures at this time but i can get some and post here this afternoon if necessary. let me know what you all think and if this post even makes sense.

Jamie Hall · January 2017

Post does make sense. And that bit of baseboard does need a vent. Only thing I wonder is why it's pitched back to the supply -- if there is a drip at the other end as you say to a wet return, why not pitch it that way instead, and let everything flow in the same direction?

jumper · January 2017

I agree with Jamie about the pitch but I don't understand why it needs a vent. Think LAOSH also describes this situation with a vent. Seems to me that a return without a trap is a jolly good vent?

Jamie Hall · January 2017

jumper said:
I agree with Jamie about the pitch but I don't understand why it needs a vent. Think LAOSH also describes this situation with a vent. Seems to me that a return without a trap is a jolly good vent?

It would be -- except I think the OP said i went into a wet return? Which would prevent the air from going anywhere?

dobro23 · January 2017

going back to the original post, i'm attaching a few pictures since what i wrote may have been confusing. it was even confusing for me to try to describe. The first and second show the baseboard in question from both ends.

the next pic is of the end of the spur off the 2" main.

and the last pic is taken from a little bit further back. here you can see the 3/4" drip from the end of the baseboard dropping into the wet return at floor level. and also the end of the spur has it's own drip but no vent. the 1-1/4" cap at the end is a little funky too. thought about adding a main vent here but haven't so far.

MilanD · January 2017

That extra 3/4 return is just insurance to make sure all condensate gets out if the valve is ever closed on that long run, and then reopened. Steam would push the co densate out and into it's own wet return. Is rad piched to valve or to drain?

unusual venting situation?

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