Please sanity check my main vent placement?

adeeshaek · May 19

Hi everyone - thank you so much for already sanity checking my overall plan for putting in main vents. I'm definitely going to go ahead.

I talked through this with an independent steam tech I've been working with, and I have one problem; we're not agreed on where the main vents should be tapped into the main runs.

I've added two examples here; the vent position in green is how I would suggest we put in the main vents, and the position in blue what he recommended.

For context, I've never so much as laid eyes on a main vent before except through Dan's books and through this forum. My HVAC tech has done this "many times before" in all types of heating systems, allegedly. He's an excellent plumber and is very skilled; I just wonder if he doesn't understand one pipe steam as well as he says he does.

I live in Albany, NY and he's still my best option - the main HVAC folks around here all don't really understand steam, and they charge an arm and a leg for very small things (I got charged $150 to have a cheap chinese radiator vent installed by the HeatingHelp.com registered contractor for Albany).

As always, I am super grateful for your help!

Steamhead · May 19

Either position will work. But if you install them on the drips, make sure you have enough "A" dimension so water won't back into them.

Also, in the first pic, the pipe that comes up through the tee, breaks right and goes through the wooden wall- where does that go?

adeeshaek · May 19

@Steamhead Thank you!

Is there an advantage to installing on the drips? The books don't mention doing this, and I would love to understand why one would do it.

The tee that goes through the wooden wall has an upward elbow on the other side of the wall, shoots up a stairwell and feeds a loop of 2 radiators on the third floor of the house.

Steamhead · May 19

OK, so that's the end of the main, and a good place for a vent. You may need to vent the riser if it's slow to heat. Don't just put a big vent on the riser, that may cause banging.

Installing a vent on the drip is one way to locate a vent if there's no room on the main itself.

Have you measured the mains yet?

ethicalpaul · May 19

https://forum.heatinghelp.com/discussion/comment/1896857#Comment_1896857

He has a 1-pipe system, and in that system, there is no such thing as Dimension A, it is a mythological construct. I have shown the water line on the far end of the main can never rise, regardless of pressure, or any other reason (save for if you do something extremely silly like use a 1/2" steam supply pipe out of the boiler—which is what I had to do in order to force anything to happen at the far end of the main.)

I am happy to point you to specific points in my videos to show you (or anyone) this. Basically, the main itself is the "equalizer" (the so-called "equalizer" does not equalize). The same pressure is pushing at the end of the main as is pushing at the boiler (for our purposes).

Edit: I always have to edit these because I know someone will find some other reason, so yes, if there is a blockage in the wet return the water will rise at the far end, but the solution for that is not the "A dimension" (which again, is completely mythological), but rather, cleaning or replacing the return.

ethicalpaul · May 19

https://forum.heatinghelp.com/discussion/204392/please-sanity-check-my-main-vent-placement

He wants to use the drip because it's a smaller pipe (and on the one photo, there is already a coupling there).

I don't blame him and it will work fine. The ideal place is on the main just after the last radiator runout, but that ideal is only easy (or even reasonable) to pipe when you're installing the main. After the main is installed it's much harder to add a vent there retroactively unless you want to drill and tap the main, and I like his proposal much better than that.

adeeshaek · May 19

I measured the main runs! Here's a map of my basement, with the mains in blue. The green notes show the places I would like to put in main vents. I've also noted the total distance from the boiler to each vent in green. All measurements are in inches.

Thank you so much for looking at this; please forgive the crude illustration

adeeshaek · May 19

He wants to use the drip because it's a smaller pipe (and on the one photo, there is already a coupling there).
I don't blame him and it will work fine. The ideal place is on the main just after the last radiator runout, but that ideal is only easy (or even reasonable) to pipe when you're installing the main. After the main is installed it's much harder to add a vent there retroactively unless you want to drill and tap the main, and I like his proposal much better than that.

@ethicalpaul thank you! So in both cases, I'll go with his recommendation

patrykrebisz · May 19

Where is the thermostat?

ALSO if you were to number the vents in the sketch, it would be easier to talk about particulars.

adeeshaek · May 19

@patrykrebisz good call - I'll mark the thermostat and number the vents. I also forgot to note the pipe sizes; they are not all the same. I'll do all these things

Steamhead · May 19

https://forum.heatinghelp.com/discussion/comment/1896882#Comment_1896882

Also, are the lengths shown on the diagram in inches?

adeeshaek · May 19

@Steamhead yes, all lengths are in inches. I chose not to put feet + inches because as someone who did not grow up in the US, I'd lose all intuition over what the relative sizes meant if I tried.

Steamhead · May 19

https://forum.heatinghelp.com/discussion/comment/1896864#Comment_1896864

But what happens if the wet return gets sluggish?

The Dead Men came up with the "A" dimension because they knew it worked. I've seen "A" dimensions less than 28 inches, but the closer you get to the boiler's waterline, the more chance that water will back up into the main- especially if the returns are sluggish.

If I put main vents in drips like that, I make sure they're above the "A" dimension. I don't need call-backs.

Steamhead · May 19

https://forum.heatinghelp.com/discussion/comment/1896887#Comment_1896887

OK. The charts we have are in feet, but we'll handle the calculations on our end.

adeeshaek · May 19

OK. The charts we have are in feet, but we'll handle the calculations on our end.

Thank you so much! Could you point me to where the charts come from? if there are any other reference texts I should look at I'd love to read them myself too; my goal here is to understand my system as closely as I can.

adeeshaek · May 19

R1

R2

R3

R4

R5

R6

adeeshaek · May 19

adeeshaek · May 19

Here's a list of my photos, with names this time:
R1

R2

R3

R4

R5

R6

adeeshaek · May 19

Here's a list of the points I think I should vent; with names this time. Please forgive the above two posts; I believe they are corrupted and I don't know how to remove them - edit does not work.

I'm going to follow this with an updated diagram.

R1

R2

R3

R4

R5

R6

adeeshaek · May 19

Here's an updated diagram with where my thermostats are. I've also added approximate pipe circumference in inches in red.

Thank you so much, again!

ethicalpaul · May 19

https://forum.heatinghelp.com/discussion/comment/1896888#Comment_1896888

A wet return takes decades to get sluggish and when that happens I'd rather find out about it from water dripping out of my main vent than have it go undetected.

But you are right, that IS a possible reason, even if I think it is pretty weak.

But the A dimension wasn't created for that, it was created due to mythological (or extremely, severely over-stated) pressure differences between the boiler and the end of the main, which if they did exist, would make the dimension valuable. But they don't. Thanks for the reply, sincerely, and congrats on your upcoming retirement!

dabrakeman · May 19

There is not a ton of volume in those 6.5" circumference pipes which would be nominal 1.5" pipe. Probably could be considered takeoffs not mains. Then you have some 2.5" mains and some 4" back at the boiler. If it were me I would try just putting a Gorton #2 at the position you have labeled as R2 and another #2 at what you label as R3 and then from there balance with the radiator vents. Should be more than enough with each roughly venting about 1.2-1.3cuft of air (some of your measurements I found a bit hard to follow but I think I am in the neighborhood). You can always add the four others if after you think you are having a really slow sector that you can't resolve with the radiator vents but seems to me like a lot more plumbing cost than I would want to take on before knowing it was needed.

Steamhead · May 19

Good idea, @dabrakeman ….. @adeeshaek , go ahead and get two of these, and let us know how it did.

adeeshaek · 2:39AM

@Steamhead @dabrakeman thank you so much! I’ll start there.

Please sanity check my main vent placement?

Comments

Categories