Venting Steam Mains

Glen_7

That setup looks a lot like mine but with the larger pipe. I understand what you are saying and will try to pick up the pieces I need in 3/4". If down the road I wanted to tap new ones along the main, can it be done on the side of the pipe rather than the top?

Thank you so much for your time and expertise.

Glen_7

Venting Steam Mains

I'm a homeowner not a professional so please go easy on me. I own an old 3 story colonial, about 10,000 sq/ft. LOTS of radiators, big oil coal boiler converted to fuel oil years ago. Needless to say, this baby is thirsty. I will probably replace the boiler in the spring but in the meanwhile, I was doing some tweaking myself after reading these forums. This is a one pipe system with the exception of some under floor heat exchangers on the first floor. I had a lot of hissing in the radiator vents so I replaced them all with higher capacity Gortons, and a lot of the noise went away. At the same time, I also increased the venting capacity on the mains. I have 3 mains, two are about 45-50 ft each, and the other is 90. Prior to my tinkering, there was only one Hoffman valve at the end of each. I installed 3 Gorton #2's on each using tees, as these seem to be the highest capacity vents. On one of the 45' mains, it seemed to vent quickly after the boiler got a head of steam. The other 45 and the 90 were still blowing off 45-50 minutes later. This doesn't seem possible. I'm worried that I maybe have a few defective vents and they are not shutting off. I could see light traces of steam coming off one of them, should I? I shut down the boiler since I'm not sure whats going on.

I didn't know how to tell this any shorter so I appreciate any responses. It isn't real cold here now (Long Island) but I want to get this straight sooner rather than later.

Thank you.

Steamhead (in transit)

What pipe size

are your mains?

Glen_7

They look like they are 3 inches but I will need to double check that with a caliper.

Glen_7

The 45' run pipes have a circumference of 7.5 inches which converts to 2.39" OD. The 90' run starts with a 9 inch circ. which converts to 2.87" OD. About 2/3 of the way down the long run it goes down to the 2.39. Should my Gorton 2's be venting faster? Did I cause a problem by tripling them up using a tee fitting? They are all mounted on top of the pipe and facing up. Thank you.

Steamhead (in transit)

If the tapping in the main and the tees

are 3/4-inch or larger, you should be OK. But if they are 1/2-inch, you can only use two of these vents per tapping. In that case a second tapping would be needed.

But I'll bet there's something else going on in that one main that vents real fast. After that one heats up, where does the steam go first?

Glen_7

The tappings at the end of each main are 3/4", however since the Gorton #2's use a 1/2" thread, I had to put in an adapter fitting to run 1/2" tees that would work with them. Therefore, the effective diameter is 1/2" out of necessity. Can mains be tapped on the sides as well as the tops? I'm asking because if I need to add more, there could be ceiling clearance issues. If the sides could be tapped I could use a 90 degree elbow. Thank you.

Steamhead (in transit)

Make

your risers 3/4-inch. If you can find a 3/4-inch cross, you can screw 3/4x1/2 bushings in that and mount your vents, elbowing up to the ones fed from the sides of the cross. If you can't find a cross, use tees with 3/4 tappings on the ends (the "run") and 1/2" on the side connection (the "bull).

If height is a problem, you can put a 3/4" elbow on the top of the existing riser and pipe your tees on a horizontal run, pitched back slightly toward the riser. Here's an example, viewed from below. These risers are 1-inch but the general idea is the same.

Steamhead (in transit)

Yes it can

as long as the horizontal portion is pitched back toward the main. This allows condensate to drain.

Glen_7

Last question and perhaps the dumbest. On a short length of 3/4 inch pipe, how do you establish pitch? Is it a matter of just applying pressure upwards to deflect the pipe a little?

Once again thank you.

Steamhead (in transit)

There are several ways

probably the easiest is to use two elbows at the top of the riser, with a close nipple between them. You can adjust the pitch by turning the second elbow. But check to see if you need to do this before installing the second elbow.

I don't have a pic of this, but we call this a "swing joint".

"Steamhead"

jerry scharf_3

Insulation

Glen,

I am no steam expert, but a thought jumped out at me.

You did not mention whether the mains were insulated. If they are not, that will certainly cause problems, especially on the long main.

jerry

Glen_7

I completed two out of the three mains with the 3/4" conversion. When I removed the 1/2" ones I installed previously, water came out so I guess pitch is an issue. Is it possible to apply heat to the first elbow and then apply gentle pressure upward to get some pitch? Not sure if I have room for a second elbow but I get what you mean.

Glen_7

Jerry-

Yes, all the mains are insulated, albeit with the old asbestos. Thats the next project for the spring. Thanks.