Main line with no vents

neurosteam

Dear steam experts,
I have a one pipe system in my house. There are two mains. The longest main has no main vents, it supplies 9 radiators. It has so many branches. I included a diagram if you can suggest where to place a main vent. The radiators heat evenly on all floors of the house but all radiator valves are hissing.

Danny Scully

Is it completely connected like that? A “loop” if you will. Or does it drop down below the waterline of the boiler somewhere?

neurosteam

It is completely connected. Some of the radiator feeds drop down to a very long wet return back to the boiler.

Danny Scully

You might consider installing “perimeter” vents, as it was likely coal at some point. It would involve drilling and tapping the pipe with threads in a few locations along the perimeter. The other option would be disconnecting the loop and allowing the condensate to drain into a wet return. You would then install the main vent at the end of the main that you’ve disconnected and dripped.

neurosteam

Very helpful suggestions. Thank you. I will look into the perimeter vents option.

neurosteam

So how is the air getting out from that loop, is it through the radiator air vents only.

clammy

Are your steam mains pitched back to the boiler and your main basically runs a perimeter and tie together ? You may have a counter flowsystem where they tied the loops together to get more even flow .you could do some investgating and see first if both mains are the same size and then find the mid point of either the load or the highest point of where they tie together and have a ample sized tee installed and most ecomically have two big mouth vents installed . Depending on how old your raditor vents are it may be time to have them replaced also . Are your steam mains insulated if not maybe it’s time to address that also it will only improve the operation of your system and put heat where it’s suppose to be . If the system is only using the raditor vents then there getting a work out .how old is the home I mostly see systems when they have no main vents they where always at some earlier point coal fired then oil w coal a lot of the counter flow systems never had main venting .so to combat it a lot of guys install the fastest vents posssible on the rads which is usually some what of a improvement but usually balancing issues . Adding a main vent usually sets things straight aside from using a vaporstat to keep the pressure low as possible . It seems larger counter flows have more of a issue I guess due to more condensate flowing back . Just some suggestion hope they help peace and good luck clammy

neurosteam

I am the home owner with limited expereince. I started reading Dan’s books. The house is built in 1910. I included some pictures.
All lines in basement are insulated.
All radiators get hot within 20 minutes up to the ones in the attic.
I replaced all radiator vents last month, still hissing with the the new Hoffman vents.
I don’t see dry returns near the boiler.
There are two small vents in the basement ventrite #31s.
One is by the short main and the other one is up by the end of the long main wet return.
Any suggestions to get the steam faster to the radiators or you tho k the system is ok.

clammy

Your near boiler piping is not up to snuff ,looks like they did a undersized header and reduce a connection to a main . I would check to see if that header is 24 inch abov3 the water line also. I would vote to update those main vents w at least 1 gorton per side . I also would remove that what looks like a check valve and install your vent tee there much better location then where it is . Make sure your pig tail is clear on your pressuretroll n that your at .05 cut in and 1 cut out .i would start out chk that . Does the water line surge and does she need to be feed water or flood back on off cycle . Peace and good luckclammy

Fred

There does appear to be some dry returns and they are vented right where they drop to a wet return. While those vents look very small and probably need to be upgraded to much larger vents, I'd like to see some pictures of a couple typical radiators. I'm thinking this may actually be a two pipe system. Do the radiators have a pipe on each end of the radiator?

neurosteam

The header is 26 inches from the water line.
I see very little movement of the water in the glass whensystem is on.
Pig tail cleared in fall. Pressuretrol setting are 0.5cut in and 1 on differential. Cycle takes about 25 minutes then done small cycles later on very cold days( we are in Buffalo)
Which check valve you suggest to remove and put a vent there. The existing vents are on 1/8th. Which Gorton vents you suggest.
Thank you

Fred

neurosteam said:

The header is 26 inches from the water line.

I see very little movement of the water in the glass whensystem is on.

Pig tail cleared in fall. Pressuretrol setting are 0.5cut in and 1 on differential. Cycle takes about 25 minutes then done small cycles later on very cold days( we are in Buffalo)

Which check valve you suggest to remove and put a vent there. The existing vents are on 1/8th. Which Gorton vents you suggest.

Thank you

Header looks like it is reduced on both ends (far end riser and the equalizer) both reductions are on the horizontal which will allow water to sit in the header. Is there any banging/hammer when the boiler starts to produce steam?

neurosteam

No banging or hammering noise when start to produce steam. Only banging at one of the vents at end of cycle.

neurosteam

Out of 21 radiators, two radiators on the first floor have two pipes. Rest are one pipe Pictures included.
The only two vents in the basement are actually connected to the two small pipes coming from those 2 radiators.
Thank you

Fred

Nice radiators, especially the one under the window. If it were me, I'd separate that loop somewhere along it's path where both halves will have about the same amount of connected EDR and put big vents on both ends of that break. That approach may mean some additional work, to make sure each half has its own return and that each half is pitched and/or dripped properly, depending on if it is parallel flow or counter flow. Also, I think those two radiators should have a trap on the return side or drop immediately below the boiler water line to prevent steam from entering those returns that have vents on them. That probably explains why you get a little hammer at that vent location.

EBEBRATT-Ed

I agree with @clammy I think a lot of it is counterflow. At least some of the main is low on the boiler end. The header looks like it's pitched toward the equalizer.

I think that's what the eccentric on the header towards the equalizer is for condensate fro the counter flow.

neurosteam

Can someone help me understand the function of this vent in the basement. That pipe going to it’s location is coming from the bottom of a two pipe radiator on the first floor. The drop down pipe is going to the start of the wet return. So it’s not connected to the main. It dies not let air in the beginning of the cycle. I only notice some air coming and some hammering twards the end of the cycle.
Photos attached.

Jamie Hall

That cute little vent is just for the radiator -- how it works is that steam goes in one end, but air and condensate have to go out the other. The condensate goes down to the wet return -- but the air can't, and so the little vent serves to let the air out. It is, effectively, a radiator vent -- just like the ones on the rest of your radiators, just in a different place. Why was it done that way? Haven't a clue.

Not a main vent. Which you need.

Fred

Was the radiator added at some point after the original system was installed? It probably does allow air to escape from that radiator as steam flows into the radiator. If there is a trap on that radiator, check it. It may be failed open and allowing steam to pass, causing the hammer.

neurosteam

Thank you Jamie. The thing is I already have a very functioning vent in that radiator.
Photo attached.

Jamie Hall

No problem -- it will just heat faster. And frustratingly defeat your efforts to control it!

neurosteam

That’s exactly what happens.
Fortunately my system works fine, I have steam up to the attic radiators within 15 minutes. I am sure based on my readings on this forum that I have an oversized boiler, something like 425,000 BTUs.

KC_Jones

neurosteam said:

That’s exactly what happens.

Fortunately my system works fine, I have steam up to the attic radiators within 15 minutes. I am sure based on my readings on this forum that I have an oversized boiler, something like 425,000 BTUs.

For me that would be excessive.

How long are your mains? The idea is to get steam available to all the rad takeoffs before any radiator "sees" steam.

neurosteam

one main is about 30 feet. there is a small main vent there.
The other main is very long, at least 55-60 feet ending in a perimeter loop with risers to individual radiators. the whole loop is closed together with no main vents.

KC_Jones

Your description is a bit confusing when coupled with the pictures you posted. I have attached a picture with colored lines added. I see 2 steam mains (red) and 2 wet returns (blue). Your description would indicate a "main" that loops all the way around and connects to itself, but I don't see that. I do see 2 mains that are connected (in error), but 2 mains nonetheless.

Could you elaborate? This may help indicate where the main vents should be located.

Jamie Hall

And at least one of those wet returns may be near or above the water line of the boiler -- which will cause several varieties of mischief.

neurosteam

Thank you for adding the colored lined. These are the two mains. The one main that heads into the picture takes a sharp left turn to the other side of the basement and makes the closed loop with multiple radiator risers. The wet return starts at that room.

KC_Jones

neurosteam said:

Thank you for adding the colored lined. These are the two mains. The one main that heads into the picture takes a sharp left turn to the other side of the basement and makes the closed loop with multiple radiator risers. The wet return starts at that room.

Have you posted a picture of this area of the loop where the wet return is? I am not seeing anything that (in my mind) matches up with your description.

Danny Scully

That vent does nothing as it clearly seems to have a check valve installed before it.

neurosteam

I posted a diagram of the loop at my first post. Here are some additional pictures of sections of the loop. Two risers are seen dropping into the start of the wet return.

Jamie Hall

Two questions. What do those gate valves do? Anything?

And more important -- where those drips go down to the wet return... where is the boiler water line in relation to where they tie together? If it is not above the junctions -- at least at the level of the window sill -- there's a problem.

neurosteam

Gate valves are always open. I did not attempt to change that. Here is a picture of the two wet returns joining behind the boiler.

Jamie Hall

That wet return which passes behind the boiler, then goes up and over to the wall -- I really don't like that one. It's too high in relation to the water line of the boiler. Is there any possibility that it could be lowered so that it was definitely below the lowest operating water line of the boiler?

neurosteam

I will ask About dropping that wet return when I do the fall boiler maintenance.