What are Air Banks?

kdshakk

Hoping you can help. A plumber has suggested that we "install 3 air banks on existing steam return lines in our basement." We recently master vented the entire building so I am not understanding what he is trying to do and I cannot get an answer. For a bit of background, this is a five-story building with a basement and a sub-basement. We have a relatively new boiler (about 10 years old) that is functioning fine. The building is actually two buildings (north and south) connected through the basement and sub-basement levels. There are 8 total living units (2N, 2S, 3N, 3S, 4N, 4S, 5N, 5S). We have done a fair amount of work on the heating system. The heating for the entire building used to be controlled from the 5th floor in the south building. Ownership changes caused us to change this configuration and we got a tekmar system for the building and Danfoss controls for the individual apartments. The goal was to balance the heat, eliminate banging AND lower our heating bills by being able to reduce the boiler pressure. We had a stellar plumber and things were going in the right direction when disaster struck. The resident in 4N decided to cut the midpoint risers in his apartment and things have been a mess ever since. They stopped using our amazing plumber and these new people don't seem to understand steam. Their first report identified our heating system as one pipe when it is actually two pipe. Anyway, this is just a bit of background. Do you think these air banks are needed for a master vented building? Any thoughts or questions would be hugely appreciated.

Fred

You need to find a new steam Pro. Anyone who can't tell a one pipe system from a two pipe should not be allowed to touch any part of that system. What is he talking about when he says "Air Banks"? Tell him to stay away from your system. Also, what do you mean when you say the tenants in 4N "cut the midpoint risers"? Did he replace his steam with something else? Why is a tenant allowed to even touch the main components of the steam system?

New England SteamWorks

kdshakk said:

We had a stellar plumber and things were going in the right direction when disaster struck. The resident in 4N decided to cut the midpoint risers in his apartment and things have been a mess ever since. They stopped using our amazing plumber and these new people don't seem to understand steam.

You already know the answer. Good steam men are few and far between. You had one and fired him. Apologize, and re-hire him.

No such thing as "air banks"...

kdshakk

Good points and questions by both of you. I called out the guy on the one pipe and was then told it was a two pipe modified to run like a one pipe, whatever that means. I feel like I am fighting a losing battle here. Tenants are NOT allowed to touch the main components of a system as it clearly states in the proprietary lease, but he did it anyway because "he was hot". I know, it sounds ridiculous and it is. The whole story is loooong and I don't want to bore you with all the details, but I feel like I have to tell you a bit more so you can see how we got here. 5N moved in and during their renovation, without telling anyone and not part of their submitted plan, removed a radiator and capped the risers in the middle of their apartment. Initially, we could not figure out why the other apartments on the line (there are 4 total) stopped getting heat from that riser. When are fantastic plumber identified the capped pipes, 5N took issue with that diagnosis. Before we could convince or force them to uncap and vent the risers, 4N had another plumber come in a cut them. We have been playing catch up ever sense complete with legal action. Because I would not allow this plumber to come into my apartment and pull through the riser pipes (which 4N wanted for aesthetic reasons) and because I listened to the previous recommendations of our fantastic plumber in modifying our radiator at our cost (per proprietary lease again), my place is fine. This whole issue is because these people were too cheap to spend a few bucks modifying their radiators if needed and instead want to malign an expert and bring in someone talking about "air banks". I am soooo angry because there could be a significant amount of money involved. Thanks for letting me rant.

Leonard

In my lease with a commercial tenant I included wordage that owner and his contractors and personal will be allowed immediate access with no delays for inspections and repairs. And non-approved modifications will be fixed and tenant charged. And tenant expressly acknowledges this may happen. NO claims will be made against landlord for any resulting inconvience. State laws may not allow immediate access for residential units, check with lawyer.

Fred

Wow, I hope you can get this under control. I am sure what this plumber is calling a "Modified two pipe system" likely means some idiot put vents on all the radiators. If so they need to come off. A two pipe system is very easy to control heat output, at the radiators, simply by throttling down the supply valve. If there are vents on radiators, they are probably there because some of the traps have failed or the system pressure is way too high. You really need a Steam Pro, not a plumber to get in there, do a complete evaluation of the system and make the needed corrections. When that is done, those who have cut out radiators will want them back because they will need them for balanced temperature control within their units.

kdshakk

This is a really old (over 100 yrs) loft building that started out as commercial and was converted to residential. We have super long radiators (10 ft +) and the vents were to help move the steam to along the length. This was done by our old plumber who is, in fact, a certified steam expert. There was the other stuff done to make this work and, Iike I said, my set up works fine. We have Danfoss valves that I find very responsive. It just doesn't make sense to me that with my place on the 3rd floor and working properly that they would surmise that the if there are issues in the 2 lofts above mine (where they are missing a riser) or the one below mine that the issue can be solved by doing things to the pipes in the sub-basement and not in the person's loft. They keep talking about releasing air, but why am I getting adequate heat? To me that makes no sense. And your point about the radiator removal is well taken.

Fred

On a two pipe system, if the traps are working properly and the piping/boiler is sized properly and the system pressure is kept low (no more than 2PSI) (The Empire State building runs at about 3 PSI), those radiators would not need vents. The air would move out through the Traps on the end of the radiator opposite the steam supply. If vents are failed closed, air cannot pass out through the return pipes and out through the venting on the dry returns. Can you put a band aid on a two pipe radiator and get it to get hot? Yes you can, with a vent. Is it the way to fix a problem on that two pipe system? No it's not. There are implications and consequences for doing things outside the scope of the original system design. Some of which your building is now experiencing. You don't know how important it is to get a REAL Steam Pro in who knows what he is doing.
Also, it is possible there are issues in the basement that is affecting radiators on other floors. They may be failed crossover traps, failed main vents, Pressure set and running way too high, incorrectly pitched mains and/or radiator run-outs, near boiler piping errors, and of course, risers that have been cut out.
I wish we could see the entire system.

AMservices

Can you post pictures of the radiators?
There is such a thing as a 2 pipe, air vented system. No steam traps. Need to see the return side of the radiator.

GW

AM there is 2 pipe with vents, but it’s extremely rare. I got to see one for the 1st time yesterday. I was tickled and smiling

the_donut

If you have access to boiler room, pictures of that would be helpful as well.

kdshakk

A few photos from my apartment. I'll go down to the boiler room tomorrow. FYI, the entire building has been master vented. Instead of traps, we have orifice valves (or plates...can't remember).

This is the photo that shows the whole length of the radiator


The shows the end that is furthest away from the trv controls. Before the pipe along the bottom was added the radiator would never get hot the full length.


This shows the radiator at the other end


These are the midpoint risers. No radiator attached, but they provide nice heat



This is the radiator in the bedroom.

GW

Is it a gravity return or pumped? Basement pics will be the ticket. I’m always curious how these so called modified systems actually keep working. You’re pretty sure all the orifices are still intact?

Fred

@GW , it's suppose to be a two pipe steam system. @kdshakk , looking at the picture of the radiator in your bedroom, I don't know how condensate would even get out of that radiator??? It is pitched towards the end where the supply pipe (I assume) is at the top of the radiator??? Does that radiator heat? Does it bang/hammer?

Ironman

IDK how a TRV could function on 2 pipe air vent system. Once it begins to close the supply, would not steam begin to enter the rad through the return line?

AMservices

I don't see any steam traps. Looks like a 2 pipe air vented system to me. Steam enters the graduated valve at the top and drains out the lower pipe with the hand valve.
If all the returns drop into a wet return, the trv's will do a good job keeping balance. Not alway the case with these rare systems.
2 pipe air vented systems were only installed for a short time before steam traps came along.
1 pipe is supposed to be larger and steam would favor that side of the radiator. The 2nd pipe would serve primarily as a drain. But the drain line didn't always drop into a wet return. They could tie right back into the main steam line.
The designers of these systems did it this way so the supply risers could be smaller and they could carry steam higher and farther in a building, if the pipe didn't have to be sized to handle condensate draining back.

kdshakk

Both radiators get hot. The radiators themselves do not bang at all. When the boiler pressure is increased ( to accommodate the North Line apts that complain of cold) then the risers bang, but not the radiators. The front radiator is pitched, the bedroom radiator is not as far as I can tell.

I think it is a gravity return, but I am not sure. Will try to find out. I really believe the orifices are intact. Not sure what the failure rate is, but one of the reasons we went that root is because they are supposed to e more reliable over time than traps.

@Ironman, not sure I can answer that question, but I can say that steam is not getting in the returns because I can feel it and tell. We have a tekmar that works on a combination of indoor and outdoor temps and then the Danfoss is set up so that individual apts can control how much steam leaves the supply line and makes it into the radiator. Forgive me if all this is obvious. I really know nothing that what I have learned over the years from our previous steam guy and reading Dan's book. This is a small coop, I was the treasurer and it was important to me to try and understand, even in a limited way, how these things work.

AMservices

If the pressure is to high, condensate can back up in the return casing water hammer. Keep the pressure low. If steam can't get in, that usually means air cant get out, or your TRV is broken. Try removing the actuator from the trv. If that doesn't do it, try temporarily removing the air vent to see if you can get steam into the radiator.

kdshakk

A couple of points of follow up:

• We did much of the initial work to be able to lower pressure on the boiler. I think we had it down to about 2 psi when they raised again because a couple of people complained of being cold. This known act may be causing the pipe banging. In my current set up steam moves through the radiators just fine
  

• We have false water lines
  

Here are a few boiler pics, but I have to admit I was not sure which area to concentrate on.
This is just the tekmar unit


This is the entire boiler room. I can say the boiler is sized correctly. The previous boiler was too big.


When the insurance company came to inspect they said the boiler set up was done really well.

AMservices

The boiler looks good. Only thing I can see is the water needs a good cleaning by the looks of the gauge glass. Dirty water will cause surging and carry over. That's when the water in the boiler shoots into the main. It can cause water hammer, take longer for the system to heat And throw mud at all the nice air vent your good plumber put around your building.
If you follow the main piping that comes out of the top of the boiler around the basement there should be main air vents at the end of that piping. If an air vent looks like it's been spitting water, then it needs to be replaced.
If you go to a problem radiator, that's not heating, Make sure the supply valves are all the way open and Remove the air vents to see if you can get steam to the radiator.


Have your boiler cleaned, Ask Whoever you get ( Hopefully another steam guy) to replace the gauge glass and clean the pressure troll pigtails (The pigtails are the corkscrew pipes that The 3 Honeywell controls On the front of the boiler are sitting on. They should also check the operation of the low water cut offs.
Ask the other tenants To check their radiators to see if the vents have been leaking.

nicholas bonham-carter

Is there a 2-stage burner on this boiler? 3 pressuretrols would indicate that possibility.
The second pressuretrol may have been supplied to cut off the high flame, and go to lower when a set pressure had been attained, and that could be a real benefit.—NBC

Ironman

Can you get a couple of pics from a different angle of the piping that's circled? I doesn't look kosher.

kdshakk

@Ironman, sorry for the delay. first chance I had to get down there. Here are some additional pics. Hope this is better.

AMservices

The low water cut off in the picture slightly lower than the one on the left hand side of the boiler Because that's a secondary low water cut off in case the 1st one fails.
The drop header ( The heavily insulated supply piping coming out of the top of the boiler) Is a sign that a true steam pro piped the system.

Fred

I guess the only question I have is that the drop header is so low, almost to the boiler water line, if not at it, is the equalizer full of water up to the header and how will that affect the function of the header/equalizer?

the_donut

> @Ironman said:
> IDK how a TRV could function on 2 pipe air vent system. Once it begins to close the supply, would not steam begin to enter the rad through the return line?

@DanHolohan if I recall correctly 1 pipe air vent style trvs should be used on 2 pipe air vent.

@kdshakk more pressure isn’t the solution. They need to size orifices properly and figure out why the apartments aren’t heating properly. A system like this was probably designed to run well under 2 psi.

AMservices

The header is below the top of the boiler, but it's above the gauge glass and the water line.
It will work much better after water is cleaned.

kdshakk

@the_dounut Yep you are correct. More pressure is not the answer. I don't know much, but I do know that. There are only 2 (maybe 3) out of 8 that are not heating properly. I think one of them has a new(ish) radiator that was not piped properly by their contractor and the other did not modify their long, old, radiator like I did mine when our steam guy recommended it. Turning up the pressure was intended (I guess) to be a short-term solution.

@AMservices I will take the water cleaning under advisement.

Thank you all so much for firing in. It is truly appreciated.

DanHolohan

@the_donut That’s correct.

nicholas bonham-carter

One way to prevent any unauthorized increase of pressure would be to install a 0-16 ounce vaporstat in place of what is there now. Try as they might, they will not be able to jack it up.
How will you convince everyone in charge that a skimming is needed?—NBC

AMservices

How will you convince everyone in charge that a skimming is needed?—NBC

Show them a picture of the mud in the gauge glass

kdshakk

Thanks for that info @NBC and @AMservices

the_donut

Does your radiator heat up on the trv side, stops, then starts to heat up on the air vent side? Do all tenants have the style trv you have? If so, are they all installed with the operator in the vertical (instead of recommended horizontal) position? Are the master vents in apartment 5N?

I think I am starting to understand, though it is hard without being there and seeing the whole system. Reminds me of an article by Dan.

I’ll try to recap what is happening, correct me where I am wrong. The system was heating unevenly. Trvs were added to reduce overheating. Unfortunately this was the wrong style and answer. You see the operator will close, and steam will condense in the radiator and create a vacuum. The air vent will pant, go from venting air to sucking air. Steam will favor whichever side has lower pressure. vacuum being lower than atmospheric pressure will cause steam to favor return side after trv closes.

Master vents were added to bring remove air and let the system heat more evenly. During renovation 5N removed radiator because why? Too hot maybe? At least 4N was too hot after the modifications.

This is complex and depending on the venting and piping will result in different dynamics. I would try to get everyone on the same page, if possible. If the system is going to be a 2 pipe air vent system, then install the correct trvs (1 pipe air vent style) and remove the trvs installed at steam inlet. Make sure orifices are installed on all radiators. If master venting is done, do it only on the top of risers in supply side.

Or convert the system to a two pipe system by adding thermostatic traps on all radiators and f&t traps on returns. Then you can keep the supply side trvs, but make sure they are installed in correct orientation so convection currents don’t close the trv prematurely.

kdshakk

@the_donut You are right,it is complex and I am no expert, but I can tell you my long radiator heats evenly and there is no panting from the vent...at all. Not sure where the master vents are located, will have to check that out. All apts have same trv style. Because I have not actually seen them I cannot speak to how they are installed, but again we are talking about a couple of apartments, one, in particular, that seems to have a problem.

I am guessing that 5N removed their long front radiator simply because they did not like the look of it. Same reason 4N cut the riser. It was not because he was hot. At that point, 5N had already capped the midpoint riser (unknown to the rest of us) so there was no heating coming from it all. 4N did not like the LOOK of the riser. So the missing midpoint riser in 5N and 4N was a personal choice.

It's hard for me to believe that our previous steam guy had the wrong approach. In fact, his approach was confirmed repeatedly, first by a steam consultant and then by engineers. Sometimes people have a hard time hearing the truth when it differs from what they want personally.

My question/issue here is that I think whatever the problem rests in individual apts, not redesigning the functioning of the boiler and doing stuff in the sub-basement to the pipes. All the apts on the S line are fine for heat. On the N line only 5N and 2N have admitted to being cold. That just don't make sense unless it has something to do with the individual radiators (the way they are piped, connected, orifices functioning, etc.).

the_donut

2’s vents may new to be replaced 5 shouldn’t have removed radiator. Few per sq ft of radiation means less warmth. 5 should put the radiator back in and 4 should repair the riser.

neilc

withdrawn