Is this an acceptable location for main venting?

nholobo

Initially had my boiler installed as a cut and paste job.  I knew I had wet steam for years and finally found a great company to do it right. I called after to find out if this was acceptable and the company doubled down on the decision of the installers. I am happy with the rest of what they did, but want to be sure after spending $ on a re-piping job.

The pipe directly above the vent tree is the wet return. I always see at least 15" from the 90 at the end and 6" up.  If needed I can extend that tree out and up.

Ease my concerns. 

nholobo

Steamhead

Give us a close-up of the reducing coupling in the main above the vents.

nicholas bonham-carter

3/4 inch pipe would be better for the horizontal of the vent tree, but it looks like 1/2 inch.—NBC

nholobo

nicholas bonham-carter said:

3/4 inch pipe would be better for the horizontal of the vent tree, but it looks like 1/2 inch.—NBC

Aside from that, any concern with location of the vent tree?

Canucker

No concern until you get a picture of the area a little farther back. Then we'll see

ethicalpaul

How is its slope? It needs to slope toward the tee side. You could use two 45s with a close nipple to get it to slant if it needs it. You’ll know if the slope is insufficient if any vent spits water.

interesting variety of vents by the way. Probably the big mouth alone would be fine or even extra

gerry gill

It is perfectly acceptable to tee off the drip for venting...however it does lower the 'b' dimension.

Jamie Hall

One minor detail -- that is not a wet return above the vent tree. If it were, that would be a useless place for venting. It's a dry return, and the vent tree on the drop to the wet return is fine.

nholobo

Steamhead said:

Give us a close-up of the reducing coupling in the main above the vents.

nholobo

Jamie Hall said:

One minor detail -- that is not a wet return above the vent tree. If it were, that would be a useless place for venting. It's a dry return, and the vent tree on the drop to the wet return is fine.

That was me using incorrect terminology. It is a dry return. Thanks for your input.

nholobo

ethicalpaul said:

How is its slope? It needs to slope toward the tee side. You could use two 45s with a close nipple to get it to slant if it needs it. You’ll know if the slope is insufficient if any vent spits water.

interesting variety of vents by the way. Probably the big mouth alone would be fine or even extra

The vent tree was made by me last year when I was trying to balance the system (mains and radiators). The installers told me it was overkill. The smaller one was on the original system so I kept it. I added the bigger Gorton and the Big Mouth later on.

Motorapido

ethicalpaul said:

interesting variety of vents by the way.

All vents matter. ;-)

JUGHNE

I think that Steamhead's concern about the coupling is that concentric reducing coupling should be of the eccentric design so that there is no water standing in the pipe giving potential water hammer.

The reducing coupling would be best in the vertical drop pipe.
As it is there is a chance that the bottom of that bit of wet pipe will rust thru eventually.....maybe years....maybe not.

ted_p

nicholas bonham-carter said:

3/4 inch pipe would be better for the horizontal of the vent tree, but it looks like 1/2 inch.—NBC

Agreed!

@nholobo, on that 1/2" tree, you're not getting the capacity you paid for out of that combination of vents.



According to @gerry gill and Steve Pajek***, at a 3oz differential a 1/2" steel pipe can vent 4.8 CFM (Cubic Feet per Minute) of air. At the same differential, the vent capacity of your three main vents are as follows:

• 0.700 CFM - Gorton #1
  
• 2.200 CFM - Gorton #2
  
• 3.600 CFM - Barnes & Jones "Big Mouth" BJ-38M
  

So although you paid for main vents with a combined capacity of 6.5 CFM, they're limited to a max of 4.8 CFM by the 1/2" pipe. On a 3/4" tree all three of those vents could operate at full capacity.

Looking at it another way, combined capacity of just the Gorton #1, and the B&J Big Mouth is 4.3 CFM, so on the 1/2" tree, that high-priced Gorton #2 only adds another 0.5 CFM of vent capacity.



A single B&J Big Mouth, plus a $21 Heat-Timer Varivalve would give you a combined vent-capacity of 4.96 CFM, more than enough to max out the capacity of that 1/2" tree, at about half the cost of those two Gorton vents & the Big Mouth.

I realize that this does not answer your question, but think that it's something you may want to include in your discussion with your contractor. If you feel this is just a distraction, please accept my apology and let me know if you'd like me to delete this post.

*** see Balancing Steam Systems Using a Vent Capacity Chart and Latest round of air vent testing- thank you Barnes & Jones!

nholobo

ted_p said:

nicholas bonham-carter said:

3/4 inch pipe would be better for the horizontal of the vent tree, but it looks like 1/2 inch.—NBC

Agreed!

@nholobo, on that 1/2" tree, you're not getting the capacity you paid for out of that combination of vents.



According to @gerry gill and Steve Pajek***, at a 3oz differential a 1/2" steel pipe can vent 4.8 CFM (Cubic Feet per Minute) of air. At the same differential, the vent capacity of your three main vents are as follows:

• 0.700 CFM - Gorton #1
  
• 2.200 CFM - Gorton #2
  
• 3.600 CFM - Barnes & Jones "Big Mouth" BJ-38M
  

So although you paid for main vents with a combined capacity of 6.5 CFM, they're limited to a max of 4.8 CFM by the 1/2" pipe. On a 3/4" tree all three of those vents could operate at full capacity.

Looking at it another way, combined capacity of just the Gorton #1, and the B&J Big Mouth is 4.3 CFM, so on the 1/2" tree, that high-priced Gorton #2 only adds another 0.5 CFM of vent capacity.



A single B&J Big Mouth, plus a $21 Heat-Timer Varivalve would give you a combined vent-capacity of 4.96 CFM, more than enough to max out the capacity of that 1/2" tree, at about half the cost of those two Gorton vents & the Big Mouth.

I realize that this does not answer your question, but think that it's something you may want to include in your discussion with your contractor. If you feel this is just a distraction, please accept my apology and let me know if you'd like me to delete this post.

*** see Balancing Steam Systems Using a Vent Capacity Chart and Latest round of air vent testing- thank you Barnes & Jones!

You're not wrong. I appreciate the input. This is really a picture of my journey of understanding of steam. When the first plumber replaced my old boiler I had just the Gorton No. 2 sitting at the top of the return (1).

I came across that document and I read it, but didn't fully understand. I ran all calculations of air in the pipes and my calculations could have been off (understatement) and built the tree you see there up and away from the opening (2). I also knew about the 1/2" or 3/4" tap being better.


When I asked for a re-piping I wasn't as explicit with the scope and we didn't discuss changing the venting at all. I was more concerned with the near boiler piping. I don't blame the installers. I'm not opposed to undoing the union below, changing to a 3/4" output and re-designing the vent tree. I'd save that project for the off season.

dopey27177

I am not one to install super amounts of main venting.

Here in this case as long as you are 28" above the water line you will be fine if you have a one pipe system. If you have a two pipe system with end of the line steam traps a dimension B will be required.

To me there is a misunderstanding about super venting the steam main.

1. the size of the piping has a resistance factor, you cannot vent
more air than the pipe will allow air to flow through it.
2. The calculations used 2,4 ounce differentials to my
understanding aremeant to be used on old vapor sysstems
where the differentials are anywhere from 2 -6 ounces
differential.
3. For the most part steam systems usually are set with 1 PSI on
and 2 PSI off. This gives you a 16 oz. differential
4. Many one pipe steam systems can be set back to operate at
8oz on and 16 oz off with the use of a vaporstat. This gives
you an 8 oz differential. So most probably your 1/2" pipe
feeding the vent valves is fine.
6. Here is something to remember, you have vent valves on all
your radiators, they vent air when the boiler firs up to make
steam. The quick vent also vents air and a Gorton #1 vents
4 cubic feet or air per minute.

Steam and air leaving the boiler slowly speeds up to at least 45 miles per hour, so once the the boiler starts producing steam at the maximum rate all the air is nearly gone from the system and the quick vent has closed and will stay closed until the next heating cycle. So why invest a lot off dollars into an air removal system that stays closed most of the time.

The only correction you need is at the 90 degree elbow at the start of the tree, I recommend another elbow (swing joint) so you can pitch the pipe to allow the condensate leaving the vent valves and pipe to drain.

Jake

Steamhead

JUGHNE said:

I think that Steamhead's concern about the coupling is that concentric reducing coupling should be of the eccentric design so that there is no water standing in the pipe giving potential water hammer.

The reducing coupling would be best in the vertical drop pipe.
As it is there is a chance that the bottom of that bit of wet pipe will rust thru eventually.....maybe years....maybe not.

That's correct. Not fixing this will shorten the life of your vents.

clammy

If it was a re pipe without explanation I would have installed a min 2 x 3/4 tee on the horizontal dry return 12 to 15 inches before the drop as is common practice . The guy was already there w a pipe machine and repiping , it would have been another 20 minutes or so and it would have been as it should be . When ever I do a repipe or a complete install I usually take the time and properly relocate the main vent if required and replace all radiator vents there usually toast anyway , no sense in taking short cuts they never pay off in the long run and if the customer wants a new boiler they need all the necessary and required parts for them to get a system the operates as it should . That concentric reducer is a no go no brainer . Peace and good luck clammy

gfrbrookline

Agree with many above, if you feed a big mouth the 1/2" you are not letting it vent properly. If you don't want to repipe you would be better served with three gorton 2's, maybe four if you remove the Gorton 2.