Main Venting

gfrbrookline

I have a one pipe steam system with two 50 foot 2 1/2 inch mains and four 1 1/2 inch returns which are all about the same length as the mains. I currently have Gorton No. 2's on each return mounted on 6 inch antlers about 18 inches before they drop. Two returns heat take about 4 minutes longer to heat then the others, which take 8- 10 minutes to heat. Are the Gorton's the right size? Should I add more of them on a tee or swap them out for Big Mouths?

Jamie Hall

OK, I'm a little confused here. We are talking about returns here? Dry returns? Or are we talking about extensions of the steam mains?

gfrbrookline

My main vents are on the ends of my dry returns and I am guessing undersized.

Fred

You really don't need to vent dry returns on a one pipe system but since your vents are at the end of those returns, it is what it is and the vents won't close and start pushing steam out to the rads until those vents close. I would add one Bigmouth, on an antler with the Gorton #2 that's already there. That should help you out a lot.

gfrbrookline

The mains terminate above a finished ceiling in a basement unit (condo building circa 1915) so I can not access them to add vents so I am stuck with having them on the dry returns. Should I only add the big mouths to the two slow returns or on all four to speed up the venting all around?

Steamhead

Why are there four returns for two mains? Are there "rise and drips" (places where the main goes up and there is a return for the condensate at that point) along the mains?

gfrbrookline

Yes, the building is built on a hill and is stepped in the middle. Two of the returns originate at the step.

Steamhead

That explains it. If you're venting at the returns from the steps, that's wrong. You want all your venting capacity to vent the entire main.

Remove the vents from the step returns and add them to the end-of-main returns and the system will heat much more quickly. Plug the openings in the step returns- you won't need them.

gfrbrookline

Thanks!

gfrbrookline

Will 2 Gorton #2 on each of the remaining returns be enough venting capacity or should I add a big mouth to each as well?

Steamhead

That should do it. Each of those mains has 1.5 cubic foot of air in it, not including the return. A Gorton #2 is good for 1.1 cubic feet per minute at 1 ounce pressure, so two of these on each end-of-main return will handle that amount of air quite well.

JohnNY

Steamhead said:

Each of those mains has 1.5 cubic foot of air in it

Good morning, @Steamhead . Did you come up with 1.5 cu/ft of air based on the poster's statement "50' of 2-½ inch main" piping?
What's that formula? I feel like that's low, but I'm basing that on nothing solid.

Gsmith

internal diameter squared times pi / 4 times length, all units in feet. I don't have the actual ID of 2-1/2" pipe handy but if you use 2.5 inches (divided by 12 is 0.208 ft) the volume of 50 feet is 1.7 cubic feet, so @Steamhead is probably correct using the actual ID and definitely in the right ballpark.

Abracadabra

Isn't it pi*r^2*length?
radius squared not diameter time pi

Schedule 40 ID is 2.469 inches or .20575 feet
Inside Radius is .102875
I'm getting 6.65 cu. ft
3.14*(.102875^2)*50=1.66cu.ft

Gsmith

Yes pi times r squared or pi times Diane squared over 4, same thing

Steamhead

That came from Frank Gerety's classic book "How To Get The Best from One-Pipe Steam".

Gary Smith said:

Yes pi times r squared or pi times Diane squared over 4, same thing

How does Diane figure into this?

gfrbrookline

Thank you all. I cant believe I am on my third boiler and this is the first time anyone inquired about having extra returns and why they would be vented, they just kept repiping them and installing ventrite 35's. The last contractor told me the Gorton's were huge overkill now you have all shown that I need 2 of them.

Steamhead

Third boiler in how long?

gfrbrookline

First was installed in 1979, Peerless, before I lived here which replaced the original from 1915. When I moved in in 2000 we still have a room half full of coal which I burned in my fireplace for 10 years. Replaced in 2005 by another Peerless, also switched to gas, which started developing leaks in 2 of the 5 sections and was replaced by a Burnham V904 last year. Not very happy that the Peerless only lasted 11 years and Peerless wouldn't give me the time of day since it is a Condo building and they classified it as commercial. Hopefully we will have better luck with the new boiler. At a minimum it will be easier to get parts and service for the Beckett burner than the old Powerflame that burned through igniters every year and only on weekends to the point that I always had a new one on hand because no Boston suppliers stocked them.

Gsmith

@Steamhead: Diane got into it by that cursed autocorrect on my ipad. I meant dia. (diameter):

Both formulas are the same: radius squared times pi times length (all in feet) = diameter squared divided by 4 times pi times length (again all in feet). Sorry.

gfrbrookline

Steamhead, I did as you suggested and capped the two step returns and doubled up the Gortons on the main returns. For the first time in 15 years the building heats evenly and the boiler runs in one or two long cycles. It has also eliminated some of the minimal clanging we had. I can't thank you enough for catching the problem.

The only problem I had is one of my Gortons started gurgling bubbles out of the vent and steam from the seam. Would you recommend another Gorton or a Big Mouth? The Big Mouth is less expensive and looks to be better constructed.

Steamhead

How old is that Gorton? If it's not that old, the Gorton people may replace it.

gfrbrookline

I moved one of the gortons over to replace the failed gorton and took the antler off the other return and replaced it with a big mouth. The return with the big mouth heated up a full two minutes faster than the return with two gorton #2's. I will be ordering another big mouth to replace all of my gortons.

gfrbrookline

Tonight my boiler ran an entire cycle without running on pressure. Granted its 35 out. All of the radiators got hot except the one in the bathroom that has a dip in the pipe and water hammers like hell right before the system usually shuts down on pressure. I have been told the only way to fix it is to tap into the elbow and run a wet return line to tie into one of the other returns. The strange thing is that all of the radiators got hot but the returns where the Big Mouth air vents are didn't get warm. I could feel air coming out and if I put a lighter by them it flickered so I know they are working. Should I be concerned that the radiators are doing too much venting? I have my vaporstat set at 16oz cut out 4 oz cut in.

gfrbrookline

I have Ventrite #1's on all of the radiators.

Jamie Hall

I wouldn't worry about the Big Mouth vents not getting warm. The idea is for the radiators to get warm! If that is happening and the pressure is fine, you're fine. In fact, since the Big Mouths are on the returns (where they belong) you really don't want them to be hot -- you don't need steam in a return, eh?

That one radiator that doesn't heat and bangs... there is no way to redo it's feed so that it can drain properly without worrying about a drip? A drip would probably solve the problem, but just maybe? I haven't seen it of course, so I can't really tell.

Fred

How much dip is in that pipe? If you can raise the radiator up a half inch or so, it may pull that pipe up enough to allow it to drain.

gfrbrookline

The banging radiator is recessed in the wall and shares a riser with the unit above me which is also recessed into the wall. There is zero play in the riser since the radiators are cemented into the floor. I thought I might be able to rework the basement piping but was told I had too many other pipes around it they couldn't get a tread cutter on the riser to shorten it without cutting everything out and redoing it.

Fred

Sounds like a drip is the only option. Just make sure when it is done that that drip drops into a wet return, below the boiler water line, otherwise it will carry steam and create a whole new problem for you.

gfrbrookline

He was going to tap it into a lower dry return so it would have negative pitch and drain back to the boiler. Otherwise it would be about 30' of piping to go below the water line. He was going to tap into the return that originates where the mains go up 6' that steamhead told me to cap the vent. I am guessing he is thinking since it is a vertical lift off the main it is the same as the step and will drain since it is still higher than the return. Will this be a problem?

Fred

If it is dripped into a dry return, it will carry steam into that that return. That will be a problem. Others will chime in, I'm sure.

MilanD

Pipe in a hoffman 17c trap inline after the drop. This should separate steam from water and air in the dry return. How many rads is this pipe feeding? May need a 3/4 trap with greater capacity. I'm not sure which model that is. This will work 100%, you'll just have to service it regularly. Maybe get one of the @Sailah's trap monitors

MilanD

Although, depending on the setup, getting it to that dry return before the main step-up may work fine. That step-up drain was there for that very reason... 17c would be an insurance.

gfrbrookline

That is what I think they are thinking. The dip is less than an inch

gfrbrookline

for what its worth it is also the last riser before the step.

MilanD

If @Steamhead thinks that's ok, I say go for it! I know people here don't like traps on 1 pipe, but 1 hoffman 17c won't kill you. Just keep an eye on it.

Sailah

The Big Mouths require steam temperature to operate. The thermostatic element in the air vent won't close unless it's at temperature. If you can put your hand on the vent body and not go "ow" then it's probably open.

I'm happy to swap the vent for a steam trap if you think that'll cure your issue. I'm just south of you in Randolph.

gfrbrookline

Not at all, I am very happy with the way the vents are working.

Steamhead

MilanD said:

If @Steamhead thinks that's ok, I say go for it! I know people here don't like traps on 1 pipe, but 1 hoffman 17c won't kill you. Just keep an eye on it.

I would use a water seal rather than a trap, since it has no moving parts. Since the off-pitch runout is above the dry return, and assuming this is in the basement where there's room to do so, come down about 3 feet from the runout with 3/4" pipe, install a drain at the bottom, then come up into the dry return. Use the drain to fill the loop from a hose.

The water standing in the loop will keep steam from reaching the dry return.

gfrbrookline

So I am making a wet trap like under the sink, correct. The pipe is right above my washing machine and a hallway so I can't come down much or everyone will be cracking their heads on it. Is it possible to come down a less and make the trap further down stream where I can put it next to a wall?

MilanD

I believe you can do as you suggest, and possibly due to it being a dead run (because of the water seal and the piped p trap), you won't be getting much steam down that pipe either. Good call from @Steamhead. I always think traps...

P trap you make by piping has to be tall enough to create static pressure that resists the system operating pressure. If it's further down the run, it should work, as long as you have enough height for the water column. Just make sure you include a so-called pet cock (drain) at the bottom of the 'U' for easier cleaning and flushing it out down the road. Gunk will collect in there for sure.