One main & its risers slow to heat (1-pipe steam system)

AHBklyn · November 2015

I am hoping the collective wisdom of The Wall can help me troubleshoot a problem we’re experiencing with the one-pipe steam system in our 1930 two-story 20x50 brick townhouse in Brooklyn. We closed on the house this summer, so we are just beginning to get to know the system and its quirks and failings.

It seems we have two “mains” in the basement that run the length of the house and feed most of the risers. One of the mains gets hot relatively quickly, and it warms the radiators on the 1FL as well as the 2FL radiators closest to the boiler room in the rear of the house. But it takes MUCH longer — 1+ hour, sometimes more — for the other main to heat up and feed the risers to the remaining three radiators on the 2nd floor (located in the front of the house). Almost always, the thermostat, which is located on the 1st floor, reaches the target temperature before steam goes up the cold risers. Basically, when the thermostat reaches the target temp (68 degrees), a quarter of the house is still cold.

Some details:

==> From the boiler room to the middle of the basement, both mains heat equally well and at the same pace, until they reach the first branches/risers. Then, in one of the mains, the steam slows down almost to a halt.
==> Probably, too much water is getting into the pipes. Sometimes, the low-water cutoff is triggered mid-cycle because too much water has left the boiler. Other times, more water ends up in the boiler at the end of a cycle than it began with (i.e. boiler is flooded) -- as if water remaining in the pipes after the previous cycle finally got back to the boiler. This is happening even though we have disabled the auto-filler (we’re doing manual feed until we figure out these problems).
==> We replaced the main air valves in the basement (located before the return) but they might not be the right size (picture attached).
==> We are in the process of replacing the valves on all the radiators, but that’s not finished yet.
==> When we first started operating the boiler, the return line was completely clogged -- water started leaking from the two main valves in the basement. A professional installed two ball valves in the return line and flushed the return, and lots of crud came out.
==> The mains in the boiler room are insulated, but throughout the rest of the basement they are not insulated (approx 35' of pipe). If at all possible, we want to keep them that way, because they are the only source of heat down there and we use the basement daily.
==> We have tried different settings on the pressuretrol -- 2 and 3 psi — but the problems continue. FYI, when we moved in, the previous owners had it set to 5 (or maybe 6?) psi.
==> We recently had the boiler checked and professionally cleaned. Seems it wasn't regularly maintained. We replaced the pigtail under the pressuretrol and replaced the filter in the auto-filler. We also replaced the gauge glass because it was completely opaque, full of sediment. Overall, the boiler seems to be working okay -- it responds to calls for heat as long as the water level is sufficient, and turns off when the thermostat reaches the target temp.

I'm attaching pictures in case they are helpful -- I'm sorry that I can't get some of them to rotate properly!!

Pressuretrol & manufacturer's label:

Piping around the boiler:

First risers from the mains in the basement:

Mains continuing through the basement (this is where one of them gets very slow to heat):

Next risers from the mains (one branch remains completely cold unless boiler is running for a long time):

Last risers from the mains (one branch remains completely cold unless boiler is running for a long time):

Main valves positioned before the returns:

I’ve learned so much just by reading the articles and posts on this site, and I sincerely hope the wisdom of The Wall will steer us toward a solution! Thank you so much in advance for any questions or advice you can offer!!

All best,
Amy in Brooklyn

Jamie Hall · November 2015

OK... for starters, the pressure is still too high. That pressuretrol setting is a 3 psi cutin, which is at least a 4 psi cutout. See if you can set it down to no more than 1 psi -- 0.5 would be better -- for the cutin. That will take about 5 minutes, and may help a lot with the water problem.

The near boiler piping isn't quite what Dunkirk wanted, but we'll worry about that later.

Generally speaking, balance problems in one pipe systems can be traced directly to venting problems. For starters, how new are the main vents in the basement? Are you sure they are both working properly -- or working at all? One possible reason for the problem in the main which isn't working is that the main vent for it isn't opening, and the radiator vents are being asked to do all the work. I'd check that. I wonder particularly as the previous high pressures may have damaged the vents.

The uninsulated piping... This isn't helping at all. I'd think pretty carefully about that.

I haven't time right now for more -- hopefully others will chime in.

AHBklyn · November 2015

Jamie, thank you so much for this reply, for starters!

Those main vents are brand new, replaced by us a month or two ago, but gosh, I hadn't thought about the possibility that the cold main might be slow to heat because its vent isn't working (even though it's new). Is there a way to test if a vent is operating properly? I assume there is -- I'll poke around the site and see if I can find an answer to that.

And yes, I figured the lack of insulation on the mains is not ideal. It seems a lot of people in my Brooklyn neighborhood expose the mains when they finish their basements and I think that's what happened in this house -- I suppose it's believed to be easier/cheaper than installing additional radiators? Who knows.

And now I have to google Dunkirk...

Thanks again,
Amy

KC_Jones · November 2015

I will also add you might not have enough main venting. How long and what size are the mains? The rule of thumb is 1 Gorton #2 for every 20' of 2" (2 3/8" OD) pipe. What brand and size are the main vents you have now? I will say this, the boiler piping is...interesting.

AHBklyn · November 2015

KC_Jones, I've attached a picture of the Maid-O-Mist valves on the mains. There is one on each main. I'm not quite sure how to identify it. Looking at the Maid-O-Mist web site it does not seem to be one of the "main valves" they sell...?

Based on the rule about 1 Gorton #2 per 20' it would seem these mains are under-vented (which I now know is a common problem, thanks to this site). Even so, is it strange that one main heats up quickly and the other doesn't?

I realize that the pressuretrol is probably too high as well, as Jamie noted. We'll start with the pressure and talk to our plumbing supply person about the valves. If we need to add another valve to both mains then that's a bigger project, I assume.

Fred · November 2015

AS has been said, those vents aren't nearly enough. Change them out to Gorton #2's and set that Pressuretrol down to .05 PSI on the front scale and take the cover off and make sure the white wheel inside (Differential is set to "1") for a cut-out pressure of 1.5 PSI. aa counter intuitive as it may seem, Steam moves slower the higher the pressure.

KC_Jones · November 2015

I can't make out which one that is, but even if it was a "D" it is roughly 1/3 the venting capacity of a Gorton #2 main vent. You need to measure the mains to determine main venting, it's the only way to do it.

AHBklyn · November 2015

Fred and KC, thank you! I will see about replacing those vents with Gorton 2s which will hopefully help even though we might need to add two more to maximize efficiency.

However, I worry that the "stems" of my vents are too small to accommodate a Gorton 2 -- which have a larger base, right? Do we need to install different stems?

Also, a related Q: I assume it's worth lowering the pressure, as you've suggested, even if it will take some time to correct the main vents? In other words, it won't make things worse -- since steam moves more quickly at a lower pressure and all? Also, if that would possibly help the water problems (as Jamie suggests), it seems worth doing immediately. Yes...?

Thanks again,
Amy

Fred · November 2015

Definately lower the pressure now. With the pressure where it is, that by itself will push water out of the boiler and into the mains. Your near boiler piping isn't good the way it is, the added pressure just makes matters worse. As Far as your Vent stems (pipe) they really should be mounted on top the the main but it is what it is. They will still vent. when you buy the Gorton vents, also buy a couple 1/4" by 1/2" couplings (I think what I see I 1/4". If it's 3/8" then buy a couple 3/8" by 1/2" couplings and replace the current coupling that the current vents are screwed into. The pipe size is still adequate capacity to take full advantage of the Gorton #2 Venting Capacity.

AHBklyn · November 2015

Hello all,

Here's an update. In sum: our problem continues, unfortunately. Any other ideas for troubleshooting would be really really welcome!

We lowered the pressuretrol to .5 outside and to 1 inside. This has helped stabilize the boiler somewhat, hooray! Although sometimes the boiler still loses enough water that the cut-off triggers mid-cycle, a minute or two later enough water returns that it starts up again. This is an improvement, because before decreasing the pressure we had to either flush the (flooded) boiler or add some water (manually) every other cycle.

We also replaced the main air valves (one on each main, positioned before the wet return) with Maid-O-Mist #1 main valves. This is because our space can't accommodate Gorton #2s. Until I call a plumber to add or reposition these valves, this is the best I can do. In theory at least, this seems an improvement over the "D" radiator valves that were there before. We also replaced the air valves on the 4 cold radiators on the 2FL with Maid-O-Mist Ds.

But still, frustratingly, the steam gets trapped halfway through one of the mains. It is so slow traveling through that main that the risers to the risers to the 2FL farthest away from the boiler don't heat up until 30+ minutes into the cycle. Testing the system tonight, I felt those cold risers finally warm up 30 minutes in, and I let the heat run another 10-15 min or so. But alas, the tenant upstairs reported that his radiators on the last riser (there are 2 on that riser) never warmed up. So, heat is still not reaching the room at the end of one line.

Does this still sound like a venting problem? Any other ideas? What should I try next?

FYI, We seem to have "C" air valves on the 1FL radiators and now we have "D" valves on 4 of the 6 radiators on the 2FL. (I believe the others on that floor are either D or C and they're older, but those radiators heat up quickly and are working ok, and we were advised by our local plumbing supply store owner to leave them be if they are working.)

Many thanks in advance for any ideas you can offer,
Amy

Steamhead · November 2015

Why are there two mains going the same direction? Was the house set up as separate apartments at one time?

Have you checked to see if the amount of radiation exceeds the boiler's rating?

KC_Jones · November 2015

AHBklyn said:
Hello all,

FYI, We seem to have "C" air valves on the 1FL radiators and now we have "D" valves on 4 of the 6 radiators on the 2FL. (I believe the others on that floor are either D or C and they're older, but those radiators heat up quickly and are working ok, and we were advised by our local plumbing supply store owner to leave them be if they are working.)

Many thanks in advance for any ideas you can offer,

Amy

It's not that simple. If you have C and D vents on rads in my opinion you are massively overventing the rads. This is sort of working for some of your rads, but basically your mains are under vented and those HUGE rad vents are kind of making up for it. You can't get the rads balanced until you have the mains right. Typically you won't see anything bigger than a 6 on a 2 story house and honestly 5 would be more common with #4 on the first floor. A D vent is the same as a #1 main vent as far as capacity goes. Also it appears as though you only have 1/4" pipe for the main vents (please verify), if so the most you can hope for is 1 Gorton #2 and maybe a #1 with it. I suspect you are going to need a bigger pipe for the vents. You need to measure the length of the mains to determine the main venting. I doubt you ever get those cold rads to heat until you get that main venting corrected. Also you will need to put smaller vents on the rads with C and D vents otherwise they are going to rob from the others.

nicholas bonham-carter · November 2015

After using a magnetic level to go over all the supply and return pipes, making sure the slope is continuous, check one more thing.
Take the main vents off, and fire the boiler until you see steam exiting both main vent trappings. There is a possibility that water in the wet returns is rising up to a level which cuts off the connection to the main venting pipe connection. The one connected lower that the other may be the slower one.
When you install the new main vents, (probably 2 are needed on each main), make sure they are drawing air from a connection higher up.--NBC

AHBklyn · November 2015

Happy Thanksgiving everyone -- I'm grateful for your questions and advice!

Steamhead, I don't know why there are two mains--there are two apartments but only one boiler. As far as I can to
Well the header splits into two mains in the boiler room and also there's a separate riser for the "bathroom radiators" (which also heat radiators in the bedrooms at the very back of the house). Each main has a huge wheel valve after the split. And they seem to both be open, we checked!

KC_Jones, that makes sense about radiators stealing steam. And it sounds like you advise us to correct the main venting before attempting the figure out the valves on the radiators. So I suppose at this point we need to find someone locally who can help us with this and possibly do some other diagnostics. Any suggestions about how to find "art of steam" people in Brooklyn who aren't what Dan calls "knuckleheads" in his book?

Nicholas, thanks for those suggestions -- next time we test I'll see if the cold main is the one with the lower vent. I would be really surprised if we DON'T have a pitch problem somewhere. Question: does poor pitching slow down the movement of steam? That might be a dumb question but I guess I was under the impression that the amount of air in the pipes is the most significant inhibitor of steam's movement, and pitch is more about the movement of condensate....

Thanks again,
Amy

Fred · November 2015

Water in the mains will cause the steam to condense at that location. Check the location of the main where you feel the steam seem to stop/slow down and see if there is a sag in the main or if it is out of pitch. Venting, as KC says is extremely important but it is not the only factor to a good steam system, pitched mains with no sags are equally important.

Jamie Hall · November 2015

A low spot in a main will almost always slow down the steam. In fact, if it is low enough, it can actually make it almost stop -- although that usually will also cause a water hammer.

What kind of valves are on those mains??? Now you have me a little worried. Certain types of valves, even if they are open, can cause the flow of steam to almost completely stop! Pictures, maybe, and any markings on the valves?

AHBklyn · November 2015

Fred and Jamie, this is helpful to know about sags in the mains. And looking at the picture I posted originally (the one with the bed below) maybe you can see that the "cold main" (closest to the picture taker) does have this slight arch to it. On the left side of that room, the mains seems perfectly level/parallel where they come into the wall. On the other side of the room, the cold main is slightly higher than the other one. I will have to check it with a level to be sure but it looks like it's arching.

What is involved in adjusting the pitch of pipes like this? Do mains like these bend over time? Or is it about the straps? Do the pipes have to be replaced if they are, indeed, arched or bent? Gosh, sounds like the beginning of a bad dream...

Jamie, yesterday we changed the main valves to Maid-O-Mist #1 (for mains), which I know are not offering as much capacity as Gorton #2s would, but without a plumber to make more room the Gortons won't fit and I want to try something ASAP to see if we could get the steam moving better.

BobC · November 2015

Buildings move over long periods of time and that can lead to sags or incorrectly sloped piping. perforated straps are a poor choice for steam pipes because they can stretch under load. Try stretching a string out along the main, that will uncover a sag PDQ.

Bob

nicholas bonham-carter · November 2015

Using a magnetic level would discover any mispitched mains. Don't rely on your eye. The string will determine whether the pipe is straight, but not the pitch.--NBC

BobC · November 2015

The longer the level, the better.

Bob

Jamie Hall · November 2015

You wouldn't think that iron pipes can bend... but they can. Enough to make a problem. But you can bend them back, just with hangars. As Bob said, the simple perforated straps really aren't stable enough; proper adjustable pipe hangars are available and can work wonders. His string trick is the best way to see if they are straight -- and a good long level to see that they slope to drain properly.

Are these great big wheel valves you speak of the vents? If so I'm not worried... as much! I somehow had the idea that maybe they were actual valves on the pipes themselves, to turn them on or off...

nicholas bonham-carter · November 2015

Alright then, use the string to check the straightness of the pipe, and a short magnetic level to check the pitch. Then after that, put some tape on the pipes so you can mark an arrow indicating the direction of flow from the reading on the level. I had a situation like this where I found the arrows I had made were pointing towards one another, indicating a sagging pipe.--NBC

Fred · November 2015

Looking at that picture, it almost looks like that main has two dips (sags) in it which might suggest that at some time the center of that pipe arched up, creating a low spot near each end of that room. Maybe it's just the picture but as others have said, put a string on it and that will tell the story.

Abracadabra · November 2015

Use your hand to feel the heat from the steam in the cold main and see where the heat stops moving.

AHBklyn · January 2016

Hello, everyone! I'm writing with a follow-up and a new problem. Eager to get your advice.

We have had several professionals stop by to give opinions. Two insisted on raising the pressure (which we turned back down after they left), so we basically ignored their advice. By far the most helpful person we spoke to was John Cataneo, whom I found via the contractors page on this web site. He gave us an objective written report with annotated pictures and recommendations. He said (as you've noted) that the piping around the boiler is pretty terrible and is likely causing problems. He also said we need to replace our boiler as soon as possible, because it is builder-grade, manufactured in 1992, and probably at the end of its useful life. That, paired with the bad piping, is causing a lot of our wet-steam issues. He noted other piping problems in the basement, as well as the incorrect pitch of the mains. He also agreed with you all that we needed to install Gorton 2s on the mains.

We were able to adjust the pitch of the steam mains slightly, in hopes of getting the water moving. We also installed one Gorton 2 vent at the end of each main, on the elbow where they turn down to the wet return. About a week after that, we replaced the air vents on all the radiators: Maid-O-Mist "D" vents on the 2nd floor and "C" vents on the 1st floor. Around that time, I noticed that the radiators in two rooms at the back of the house -- the two rooms "stacked" above the boiler room -- were heating unevenly. This was surprising because we never had a problem with them before, they always heated quickly and immediately. There was also the sound of sloshing water. Then, we then left town, and during the first week of January, when the weather got really cold, we received a complaint from the tenant upstairs that he was getting very little heat in the room with the "sloshing" radiator. And indeed, when we got home, we discovered that the radiators in both of those rooms above the boiler room -- which used to be the first to heat -- are now the last to heat, if at all.

Possibly important note:
These two radiators are fed with their own risers, straight from the boiler -- they are not attached to the steam mains running through the basement but are fed directly by two smaller pipes (1-1/2" probably?) attached to the header. Each radiator has its own pipe/riser. The pipes snake through the boiler room and have a couple of right angles. They seem to be pitched okay, though I'm certainly no expert on that. I am assuming they are pitched okay because until recently the radiators were operating just fine.

Symptoms:
- Both radiators have that water-sloshing sound.
- Severe water hammer when the steam starts to get through -- the riser leading to the 2FL radiator snaps and shakes and vibrates pretty violently at times, in fact.
- Panting air vents when the boiler turns on (they inhale and exhale pretty severely).
- Uneven heating: the radiators have four sections, and the outside sections (far left and far right sides) heat first, followed eventually by the middle sections.
- The problematic 2FL radiator was spurting water from the air vent at one point, though I'm not sure that's happening anymore. (The boiler was flooded when we got home so there was definitely wet steam in the system when we first noticed the problem.)

Troubleshooting we've done so far:
- Increased the pitch of both radiators toward the valve.
- Added some *makeshift* insulation to the pipes in the boiler room that feed these radiators. Our "fix-it person" brought over some fiberglass pipe insulation he had (extra from another job), but it is for 2" pipe, so there are gaps between the pipe and the insulation. We went ahead and installed it anyway, figuring something is better than nothing.

Questions I’ve pondered:
- Drain the pipes? After poking around HeatingHelp.com, I see that "panting" air vents suggest condensation might be pooled and trapped somewhere in the pipes, and that we should make sure everything is pitched correctly. But things seems to be pitched fairly well; plus, those radiators were working okay before we installed new vents on the mains and the radiators. That said, the temperature has dropped dramatically here since we installed the vents, so conditions have changed and might have exposed a problem we didn't know existed...?
- Could this be a consequence of installing the Gorton 2s? Since these radiators are fed directly by the boiler (not branched off the main), do we need to add venting to them somehow?
- Would changing the vents on the radiators help? (i.e. change the “D” and “C” vents on the radiators to Maid-O-Mist #1s?)
- Could it be cold pipes in the boiler room?

Many thanks for any thoughts and advice you can share. I'd appreciate it!

All best,
Amy

KC_Jones · January 2016

First thing the vents you put on the rads are almost certainly too big. I fear you are trying to compensate for lack of main venting and it usually doesn't end well (as you are finding out). A D vent is as big as a main vent. This will also cause the symptom you are seeing with the first and last section heating, but the middle not. This is known as short circuiting and what happens is the steam rushes in so fast it just runs to the far end of the radiator right to the vent. The vent closes then you lose heating capacity of the rad. Are you positive the valve is fully open AND is working correctly? Are you hearing the water sloshing in the radiator or the pipes? If the valve is partially closed or is broken and won't open correctly you can accumulate water in the radiator and cause the issues you are seeing. I have done this by accident and on purpose in my own house to witness the effect of a closed or partially closed valve. On mine it can sound almost like a gurgling or sloshing sound in the vicinity of the valve/pipe. This is due to steam trying to get through the water that has built up in the radiator behind the valve. The only other thing would be bad pitch. Make sure the entire run out of those rads is pitched back to where it connects to the boiler piping.

vaporvac · January 2016

You mentioned you re-pitched the mains. Could this have shifted the pitch of the header to which these runouts are attached?

Fred · January 2016

I also suspect, by putting all those large vents on the radiators and the Gorton #2 at the end of the mains, you have made those mains/radiators the path of least resistence for the steam. The two 1-1/2 radiator run-outs should not be attached directly to the Header. They must be moved to the Main(s) as, one pipe systems will feed condensate back to the boiler through the sammse of those two Run-Outs, back into the header, whose major purpose is to help dry the steam. What you have is defeating the purpose of the header (or at least significantly crippling it). Use slower radiator vents or adjustable ones (good quality ones. Not the ones sold by HD) I hate to say it but that piping is a mess.

One main & its risers slow to heat (1-pipe steam system)

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