2-pipe steam heat system ?

angelotrivelli

I've started to do some research on my steam heat system this summer so that I can get a grip on the banging sounds next winter. My first step was is read Holohan's book, "We Got Steam Heat!"

I love the breezy prose, but now I got a question.

On page 40, he describes a one-pipe system, with one pipe and an air-vent. On Page 48, he describes a two-pipe system with, two pipes and a thermostatic trap. So one of the first things I did was to look at my radiators.

They're all different sizes but they all have two pipes and an air vent like this pic:



The vents all happen to be Hoffman Industries #40 air vents. Looking on the internet, I see these vents are intended for ONE-PIPE systems. That makes me a bit puzzled. There are definitely 2 pipes on my radiators, but I don't have thermostatic traps and I am pretty sure I don't have an F&T Trap in the basement.

So, what type of steam system do I have? I am guessing it's more like the "one pipe" system except there's just another pipe to help the condensate get back to the wet return without encountering steam ?

Whatever the case, I do have serious water hammer, resolving that is my ultimate goal but first I need to understand exactly what I am dealing with!

ratio

How old is the building? It could be a two pipe air vent system, uncommon but not unheard of. It could also be a two pipe system that someone 'fixed'. I'm leaning towards two pipe air vent, because I don't see a a trap on the return.

angelotrivelli

Thanks! the house is at least 120 years old and probably used fireplaces initially, no idea when it was switched to steam.

There's definitely no thermostatic traps on any of the radiators, they all have 2 pipes and one air vent like the one pictured.

So that's the name of this configuration, "two pipe air vent" ?
Are there are any characteristics or features I should know about it?

KC_Jones

I'm leaning towards yours being a 2 pipe system and none of the vents should be there. They are in the wrong place indicating they aren't original to me.

Not all 2 pipe systems have traps, some use orifice plates to meter the steam and keep it from getting to the outlet.

To my knowledge all 2 pipe air vent systems have both pipes connected at the bottom and most if not all traditional 2 pipe systems have the pipes connected like yours.

If it was originally a 2 pipe system that didn't use traps, other parts of the system could have been messed up over the years and you may need to investigate further to figure out how to get it working as designed, if that's what you are interested in.

Jamie Hall

I think I agree with @KC_Jones on this. A two pipe -- quite possibly very low pressure -- which has been seriously knuckleheaded over the years. The other reason -- besides the odd vent placement (the vents are placed where one would put bleeders, if this were a hot water system, suggesting that whoever put them there was not knowledgeable) is that there are no valves on the return pipes at all; the two pipe air vent systems had valves on both the "feed" and "return" pipes.

Unhappily, chances are that the added vents are not the only "fix" which has been applied over the years.

So where to begin. Hopefully one of the "fixes" was not concealing the pipes in the basement. Therefore, you need to trace all the pipes out, and figure out which ones were used to supply steam from the boiler to the radiators, which ones, were used to allow condensate (and, very likely, air) to get back to the boiler (these will be near the ceiling, but probably a bit lower than the steam lines) and which one, if any allowed only condensate to get back to the boiler -- these will be at or near floor level in the basement (I hope they're not buried). Make a sketch or a diagram.

Then, since you know you have water hammer, you can begin to find out why: water hammer occurs when condensate in a steam main (the supply pipes) or a dry return (those high level return pipes) can't drain freely either back to the boiler or to one of the wet returns (those low level pipes). You need to go along every inch of every upper level pipe, including the feed and return pipes to all the radiators, thinking like water: "if I were water in this pipe, how would I get back to the boiler?" and remembering that water doesn't flow up hill. You're looking for pipes pitched the wrong way, or pipes with sags in them.

You also need to look at how the boiler is piped (some photos of the boiler and the piping near the boiler would be very helpful!). Odds are good it's wrong, but how wrong is the question. Some wrong piping, while bothersome, can be dealt with. Other problems, not so much.

You also need to look at the boiler controls, particularly the pressuretrol. Again, odds are it's set too high -- possibly much too high. If it's the plain grey box variety, with one scale on it, that scale should not be set higher than 1. If its' the variety with two scales on it, it may be subtractive -- take a picture of it so we can advise.

All that's for starters...

And take heart, you'll get there and have a nice quiet system which costs less to run by the time you get done.

angelotrivelli

Thanks everybody for the information. This is very possibly a knucklehead situation! I am going to carefully inventory and diagram what's in my system and report back when I find more interesting things!

jumper

That branch coming off the vertical supply is not nice.

Jamie Hall

jumper said:

That branch coming off the vertical supply is not nice.

No, it isn't. I saw that one, too. I doubt, though, that's that the only odd piping which is going to turn up... if the pitch of the pipes is OK, and the riser itself is big enough, it may come under the heading of it works; don't know why, but it does. Tying the two radiator returns together like that might be a problem, too -- maybe. Might not. Have to see what really happens.

Steamhead

@angelotrivelli , I agree- it's probably some sort of Orifice Vapor system. Post some pics of the boiler area, also of any air vents you find on the basement piping.

Where are you located?

angelotrivelli

I am in an old house in Philadelphia, it's a 3 story structure with 12 radiators. The boiler happens to be a CEG225EID from Columbia (see attached spec sheet). It was installed in 2015 and replaced an almost identical boiler which had started leaking water. Water hammer sounds as boiler heats up has always been a problem since we've moved here 7 years ago.

Below is a photo of the boiler (sorry for the mess in the basement going to clean it up this summer!).

Right off the bat, there are a few things which are at least questionable (based on my novice understanding of Holohan's book):

• The header is composed of copper piping and not cast iron. There is some bright green corrosion on one of the joints.
  
  
• The steam main is midpoint on the header between two risers. That's wrong? It will keep any condensate which forms in the steam main from getting to the wet return.
  
  
• There is no insulation on the basement steam piping.
  
  
• Looking around in the basement, I don't see any vent-type devices. I might have missed them.
  

Jamie Hall

Well... the near boiler piping isn't doing you any favours, that's for sure. How much it is contributing to the water hammer problems is hard to say, but... sigh.

Are there any other pipes, other than the one equalizer I see in the far back corner of the boiler, which allow condensate to return to the boiler? And perhaps at least as important, check the pitch -- as I've mentioned before, I think -- of all of the steam pipes while thinking like water: how do I get from here back to the boiler? It's not at all uncommon in older houses (particularly when dealt with by a plumber who plumbs risers in copper, with a too small a header, with the steam takeoff in the middle and the equalizer at right angles to the header and...) for the pitch of the pipes to have gotten -- for lack of a better term -- wonky.

You will want to insulate all the steam pipes, but don't do it until you have determined that they are pitched enough, in the right direction, and fixed any problems. Much easier to do that before you insulate!

RyanD

Nice reducer on the vent also.

angelotrivelli

Thanks Jamie,

Yes, that pipe in the back goes down to the wet return at the bottom of the boiler and also a valve.

The is a smaller diameter pipe connected to it which happens to connect to the returns from the radiators. I have a pic below...

ethicalpaul

Maybe some clarity: The pipe on the floor is what I'd call the "wet return". The other pipes in the photo above are parts of the "equalizer" and "Hartford loop". I believe the Equalizer is what you see dropping into the tee with the drain valve.

angelotrivelli

@RyanD, yeah, that's a whole other problem! I might attempt later to start a separate discussion about it... basically that goes into a crawlspace under an addition where there's a blower that forces the exhaust to an external chimney that runs up the side of the house. Is it up to code ? ¯\_(ツ)_/¯

Old houses in Philly are full of bizarre sketchy workarounds !

Steamhead

@angelotrivelli , whoever installed that boiler should not be in the business. Have it repiped. There are plenty of Steam Men who work Philly- go here to find them:

https://heatinghelp.com/find-a-contractor/

angelotrivelli

@Steamhead, yep, that's my project to finish before next winter (not me personally, but finding a good steam person). I got some other issues to address and the re-piping and water-hammer resolution will become part of it.

I wonder now if the previous boiler had cracked because of bad piping issues. It lasted only ~10 years!

mattmia2

So they had 2 chances to read the manual and didn't...

Have them put in the appropriate valves to flush and blow things out while you are having it repiped.

How much makeup water is it using? That is what usually kills a boiler.

angelotrivelli

@mattmia2 , that's a very perceptive question!

If by "make up water" you mean city water that gets pumped in occasionally into the boiler-- it was using A LOT until this last winter. Basically we got a dank crawlspace under an addition which has pipes to 2 radiators. Some of the piping had rusted to the point where steam and water were dribbling out. It wasn't noticeable by me until it got really bad (wisps of steam coming up through floor-wall interface). I happen to know the previous owner also had problems with rusted out pipes in this crawlspace. But yes, after getting that pipe fixed I didn't hear the make-up-water pump at all for the rest of the winter.

This stuff is so interesting... too bad it's going to cost me a lot of money!

Formerly

That CSST hanging about worries me a bit, electric potential is no joke...highly doubt it's properly grounded to it's surroundings....

mattmia2

Fresh water from the city brings oxygen with it. That oxygen rusts things. It would be a good idea to turn off the supply and check the level after each cycle for the first couple cycles and see if it drops then check it maybe twice then once a day for a couple weeks and see if it is losing water (but don't let it get low). Losing a little water as it vents the air and such is normal, but it should be weeks or more before you have to add water. If it is loosing a lot of water then you have to figure out where it is going or you will destroy another boiler. Another option is to but a water meter on the feeder(I think some electronic feeders will tell you how much they have added).

mattmia2

Is some cable tv or tv amplifier powered off the boiler's convenience outlet?

angelotrivelli

@mattmia2, the leaking was stopped this last winter. It had been dribbling out of a severely corroded radiator pipe in a crawlspace. And yes, that convenience outlet is being used to power a cable signal booster.

My pic seems like a crime scene now

dopey27177

The system you have is a two Pipe air vent system. It is subject to the rules of one pipe steam.

What is odd about it is the fact that the steam supply is piped in at the top of the radiator. Additionally the return side piping is usually one pipe size smaller than the supply.

About the air vent, I worked on many systems like this in New York City, the air vents were placed in the center of the radiator not the top. If your heat works well leave the vents where they are.

As to the banging, the first thing you need to do is check the pitch on the steam main and any horizontal steam pipes in the building including the return piping as they sometimes are charged with steam, replace all the near boiler piping, and insulate all the steam piping not the returns.

In my book you will find this system explained and several variants.

The way the radiator is piped aand if all therads are piped the same way you can convert it to a system with steam traps. Me I would leave it alone.

The is system should operate at no more than 1 PSIG.

Jake

Jamie Hall

Ah, Jake... I think we agreed it was an orifice vapour system...

dopey27177

To Jamie hall

No orifices were used in the systems I serviced. This one is a bit of an oddball. If you look closely it appears the rads have separate returns.

With a separate return you wont have steam crossing over from the sister radiator.

Still remember no more than one pound of steam pressure. A differential of 4 is a good setting.

Jake

The Steam Whisperer

Looks like a single return for 2 radiators to me and the radiator is a hot water style radiator... making it a later system than 2-pipe air vent systems. The vent is at the top of the radiator, which is probably not where is would have been placed if it was original to the system.....that usually an idicator of a later knucklehead.

JUGHNE

The first picture posted shows 2 rads with the returns wyed together.

This house has an addition, we don't know if the original section may have been OK with orifice type supply valves.
Then the house addition could be a real hack job.

The power venter into the crawl space chimney is another indicator.

The existing horizontal steam main may have been pulled down making that section a counter flow.....adding to water hammer.

At least they have both supply outlets in use.
Even skim tees on both sides.
I&O book shows them to be only 2".....so no reducers to remove.