Main vent questions - newbie

Well… I wouldn't worry about the Gorton #2s. There have been some QC issues, but in general they are a good reliable vent.

Now… that sloping pipe. As it is, it could be a problem. However, I think that if you take the reducer off under the big pipe, and put a 45 on there angled up with say a three inch nipple, then a 90 towards the room (to clear that other black sloping down in back) and your Gortons on there it should work. Adequate headroom. There will still be a bit of a puddle there — can't help that — but it may work just fine.

Two #1s will likely be adequate. IMO you’ll probably see more success speeding up the venting on the far radiators and slowing it down on the near radiators than you will going crazy with the main venting.

Like others on here I’ve found the Big Mouth vents leak a lot of steam and I removed mine because I was losing 3/4 inch or so of water per week. Now I have two MOM #1s on each of my mains and lose basically nothing.

You appear to have two #1 vents on the pipe now and the pitch, while not ideal, appears to properly serve the vents. Are you sure you have a problem? If you truly need to correct the backpitch, you can probably jack up the pipe an inch and apply a hanger…

The two #1 vents are probably adequate, and you can add a third if more venting is indicated.

As others have mentioned, vent your radiators properly.

Looks like it is a parallel flow main so it has to slope toward that dry return. That dry return has to drop down below the water line before it connects to anything else like another dry return. Does it do that?

Did you say that there is another vent in that dry return at the boiler? You could put all the venting there and cap the vent with the slope.

That pipe as is will hold a pocket of water which will collapse steam at that area and usually will hammer since the vent is beyond the pocket, the vent will allow steam to get to the pocket.

If you are using that vent connection you show, you need to remove the section at the tee where it connects to the dry return and use bushings, ells, 45 ells, and nipples to get the pipe to the vent sloping toward the main. It could be 3/4" after the tee.

With the right tools that pipe coming out of the tee should unscrew but you could also cut it about an inch from the tee, make 2-3 slots inside the pipe almost to the threads, and use a chisel or punch to collapse it between the cuts then it will unscrew easily.

Unless this is a very big system, those timings are a bit long. Is this a two pipe or one pipe system?

It looks like your steam pipes are uninsulated; that will slow down the process of heating the pipes from cold and getting steam to the radiators.

Older boilers with high thermal mass can take a long time to produce steam from a cold start. It happens much more quickly during colder weather when the boiler is still hot from previous cycles.

One thing I've done is take the main vents off completely, leaving a 3/4" hole, and time how quickly the main heats all the way around with the vents vs. with the hole. If there's not much difference, which depends on the size of the boiler, then you've got enough venting.

In my basement I can hear the air puffing out of the vents, so I know they're working. It's not real loud but it's easy to hear over the noise the boiler makes. If air can get past the wrong slope it's probably OK. We're not pushing steam through that once the main is hot. Jacking the end up an inch sounds like a plan.

Pigtail on the gauge could be plugged. Seems to take a while to heat. How about a few pictures of the boiler and the piping.

If your short of venting the boiler would probably build pressure. Any white smoke coming out of the chimney?

I would start the boiler and let it run just until the steam outlet pipe gets to the point you can't hold it. Then start timing and see how long it takes for steam to get to the far end of the main. Then see how long it take for most of the rads to heat.

That will tell us something about the venting.

Is this oil or gas? Has the BTU input been checked?

Another task for you (a simple one) is to measure all the rads and determine the EDR capacity of all the rads and compare it to the boiler size on the boiler name plate. Compare EDR (or sq feet of steam same thing)on the boiler to the total radiator EDR. Don't get confused with BTUs.

@BostonDad I rehabbed a steam system on my building in Brookline which heats approximately 25Ksqft by popper venting and would be happy to look at your venting. based on your run times I think you are way under vented on the mains but may also have issues with the radiator vents being undersized. I am not a professional just a guy who took over a condo complex that spent way too much money to heat the place. My heating bill just reached what we paid for oil 20 years ago and it is all about the venting knowledge I got from this website. If you would rather have a pro reach out to @New England SteamWorks.

You don't have a huge system so you could use Vetrite No 1's on your radiators which would allow you to moderate the venting for each room to control the temperature after you figure out your main venting. If not I would suggest reading Gerry Gills venting chart which can be found on this site.

If you want a Pro and @newenglandsteamworks isn't available Macfarlane Energy has a guy nicknamed Boomer who is really good with steam.

This one pipe system and has two mains. If the 'Steam Main extensions' from each main are not connected below the water line (typically near the boiler) you are just inviting problems and a lot of unnecessary work putting the vents near the boiler.

Just change the venting pipe that exists so it doesn't trap any condensate (restricting the air flow) as mentioned earlier in the thread and increase the main venting as also previously mentioned. Then see how the system performs.

@gfrbrookline Take a better look, the vent is at the far end of the main that has the issues. The other on the "return" was removed.

"The main vent was clearly way undersized. The longest section, a 41' long 2" main, had a single Vent Rite 35, with an additional Vent Rite 35 at the end of a 10' dry return. I replaced the first vent with two Gorton #1's and removed the vent on the return. Since then, I've read advice on this forum that two Gorton #2's would be more appropriate. I have a couple of questions before I proceed."

Think of it like a garden hose, if you punch two large holes in the hose next to the faucet will you have any pressure at the nozzle to water your flowers? Venting at the end of the line is like watering your flowers with steam heat to your rooms.

I have no clue what you are looking at. The vents are at the far end of the longer main. Your analogy makes no sense to me.

If that pipe is at the end of a main it is pitched wrong based on your level and will fill with water so any vents you put there won't work because the air won't pass through the water that will settle in the pipe. You need to relocate the vent if you want your system to work properly.

Note the continuous pitch back to the boiler once the steam has turned back to water.

Another question that I can't tell from the pictures is;

You have two mains are there two returns ? If so are they connected above or below the boiler's water line. How long is the shorter main and its return ?