The main is hot, the radiator is cold, and the heating company can't figure out why.

bmearns

We're home owners with a one-pipe steam system. Everything was working well except the boiler had a leak, so our heating company told us it needed to be replaced. Made sense. But it took over a year for them to get us the proposal and actually do the job. When they replaced the boiler, they switched us from oil to natural gas.

The boiler install seemed to go fine, but ever since, we've got three radiators that won't get hot. They won't even get warm, and one of them is in the room with the thermostat, so the rest of the house is baking.

There are two mains coming out of the boiler. One of the newly-cold radiators is on the "back" main, and the other two are on the "front" main. On the front main, one of the colds is on the first floor (with the boiler in the basement), and the other is on the second floor.

We've had the heating company out four times now! They're stumped. One of their younguns tried to convince me it's a closed system, so once it was done pushing all the air out, there wouldn't be any more air in the system. Now the extent of my HVAC knowledge comes from about 90 minutes of Dead Man's Steam School videos, but even with that basic knowledge, I'm pretty confident he was dead wrong about that.

So they've replaced the vent cans on the bad radiators, and on most of the other radiators as well. They've replaced the vent cans on both mains. They've lowered the Hartford loop by a few inches because the water level in the sight glass was full most of the time. That's their explanation, I can't figure out if it makes any sense. When I mentioned "A dimension", I got the sneaking suspicion that they were only pretending to know what I was referring to.

Where we're at now is that after the heat runs for a while (like a good 90 minutes, we've only got about a 2000 sq ft home), both mains are hot all the way to the end. I find the riser that feeds one of these cold radiators (the one on the front main, on the first floor, and in the thermostat room), and it's hot on both sides of the radiator. But the radiator is cold. I can hear and feel air pushing out of the vent, but it's not steady. Not that I'm really sure how the air should be moving through it.

I keep trying to hint to the techs the only thing that makes sense to me: there's a "clog" preventing the steam from getting into the radiator. Maybe sludge build-up, maybe the service valve is bad. I have no idea, but it just seems like if the steam is getting there but not getting in, there's something blocking it. They don't seem to have any interest in pursuing that. One guy said "that's a can of worms" but it's the only thing that makes sense to me anyway, especially after everything else they've tried.

Mind you, they're paying for all this because they've freely admitted that everything was working fine until they replaced the boiler, so they're implicitly admitting that it was their fault. I don't know if that's right or not, but they're not charging us, so any idea that they're just jerking us along to squeeze money out of it doesn't really make sense.

I was talking all this over with a friend who knows nothing about steam heat, but he's a physics professor and a pretty smart guy. He points out that it would be weird for three radiators that were working fine to suddenly develop clogs at the same time, or for all three service valves to suddenly break at the same time. He makes a fair point, but we came up with this theory to rationalize it: when they replaced the boiler, that's all they did. "Flame heads", as I believe the term is; they spent all their time in the basement. When we first called about the cold radiators, the tech comes out and (this is just speculation) the first thing he does is check to make sure these 85 year old service valves are open. That seems like a reasonable thing to check when someone says their radiator is cold. Now before he's done (this part is fact), he determines that they were supposed to replace the vent cans when they did the boiler. They didn't do that, so he did that, on the cold radiators, and on one (for some reason) of the two mains. So our pet-theory goes that the vent cans were the initial problem, as he supposed. But in the process of investigating, if he toyed with these old service valves on those same radiators, he may have created a new problem on all of them, all at the same time. I'm also lead to understand that the year-long leak in the boiler introduced a lot of fresh water, which means a lot of fresh oxygen, which means a lot of extra corrosion, so these service valves that were already really old may have been getting worse and worse for a year or more, just waiting for someone to come along and give them a twist. But as I said, that's just a pet theory from a couple of guys who don't know much of anything about heating.

I think I've been listening to too much of Dan's podcast because this turned into story time, but can anyone help me? Help me understand what might be happening? Help me with what to look for or test? Help me with how to get my heating company to actually find a solution here, when clearly they don't have any steam experts on staff?

Jamie Hall

Wait a second. In one place you say it's hot on BOTH sides of the radiator?

What's hot on both sides of the radiator? There should be just the one pipe coming into the radiator? If there is just one pipe, and that one pipe is hot but the radiator is not… there really are only two possibilities: the vent is defective, which is unlikely but possible, or the valve isn't open.

However, let's go back one step. How fast does the pipe to the radiator get hot?

KC_Jones

That was long, but I'm sure it's from an emotional position of pure frustration.

So, few questions and requests to help us guide you.

1. we need to see pictures of the boiler install. Overalls that show as much of the piping they did as possible.
2. Did they skim the boiler after installation?
3. Do you know how they're sized the boiler?
4. Tell us how long and what size your mains are. We can help if you aren't good with pipe sizes.
5. Show us pictures of the main vents you have.
   

That should be a good start and get the conversation going.

fernandobrea

I am actually having the same problem. I have super hot main pipes, cold radiators, plummer come and go chang8ng traps, valves, draining return lines and after 1600 in bills no one know what is going on. My problem started when I replaced the oil burner by a gas burnur. The boiler is firing up and the main pipes are getting hot. for some reason the radiators (all of them) are not getting hot)

Jamie Hall

@fernandobrea , is yours a two pipe system? If so, where are the vents on the dry returns?

fernandobrea

I have a 2 pype system. vent on the dry return is in the basement runing along the celing about maybe 5 ffet from the boiler. I took it of to make sure the valve is properly working and it is working

20230317_183213.jpg

ethicalpaul

Oh dear, please make your own thread with your own questions on it rather than taking over this poor person's. They've got enough trouble 😪

PC7060

re the the original poster; what @KC_Jones said.

bmearns

@Jamie Hall - Sorry for the confusion: it's a one-pipe system. What I meant by "both sides" is in relation to the riser (if that's the right word) that comes off the main and feeds the cold radiator: the main is hot on both the boiler side of this riser and the other side of the riser as well. So there's no question (to me, at least) of whether or not the steam has reached the radiator yet. It's knocking on the door, but can't get in.

EDIT: Regarding how fast the pipe heats up. In my opinion, it's slow. I don't know how fast it "should" heat up, but the heat certainly isn't moving at 60mph down the main. I'll try to investigate more tomorrow and get a more concrete answer. Off hand, I can only say that on a main pipe that might be 60 feet long at most, I checked it 40 minutes after the heat started up the other day, and it wasn't hot all the way to the end. But some of the radiators along the main were.

@KC_Jones thanks for the response, I'll get some pictures tomorrow and post them. I'm definitely not good with pipe sizes, is there an effective way to measure them with, say, a tape measure and string?

PC7060

Re way to gauge pipe size; 2" iron pipe (bare) is around 2-1/2 wide with approx 7-7/8 circumference. You can scale up and down proportionally for larger pipes.

mattmia2

https://forum.heatinghelp.com/discussion/comment/1744295#Comment_1744295

There's a 3rd possibility. That section of main is not hot because it is full of steam but because it has water flowing through that is being thrown out ofthe boiler because the near boiler piping is wrong and they didn't skim it.

This also explains the boiler overfilling. the auto feeder comes on to refill the boiler during the cycle because the liquid water is out in the system instead of the boiler then when the burner shuts off and the wayer returns to the boiler it is overfilled.

You should probably get and read "We've Got Steam Heat".

BobC

The system worked fine until they changed the boiler and the steam mains both get hot to the end.

The house may have settled some over the years and the slope on some pipes has changed, when the new boiler was put in they may have pushed the mains up a little bit and moving that main also moved the radiator leadout pipes off the mains as well. That could change the slope of the leadouts and you may have some water water trapped on a newly mis sloped pipe feeding a radiator. That water will condense any steam trting to pass over it robbing the radiator of steam.

fell along the leadout pipes of a problem first floor radiator to see if you can feel where the steam is getting hung up. Try raising that radiator by 1/2 to 3/4" on both sides and check with a level to make sure there is still a little slope back towards the boiler so any water can flow back to the boiler. Now see if that rafiator heats or if the steam gets closer to the radiator that is now higher.

Bob

JohnNY

"Heating on both sides"? Like this? This was a fun one I got to solve where steam passing through a broken trap in another room was steaming up the returns. Thermal imaging solves problems. (Stop putting vents on trapped radiators, people)

bmearns

Alright, tried to get as much data as I could, hoping some of you can help turn that data into information. Regarding the questions posted by @KC_Jones :

1.we need to see pictures of the boiler install. Overalls that show as much of the piping they did as possible.

I'll post these below.

2.Did they skim the boiler after installation?

Not immediately. The first tech who came back a few days later said they should have done that, so he did it. He also told me it would need to be done frequently. He changed his story a bit on this, kept going back and forth between "every day" and "once a week" for the first several weeks. So he told me I could do it, I did it a few times, but when another tech came out a few days later, he seemed surprised and mildly horrified that I skimmed it myself.

3.Do you know how they're sized the boiler?

I don't know. It's overall size is somewhat smaller than our old one, but I just kind of assumed that was because of improvements in technology and/or changing from oil to natural gas.

4.Tell us how long and what size your mains are. We can help if you aren't good with pipe sizes.

I measured the circumference of the main at 7+9/16", so sounds like a 2" pipe. I did some rough measurements of the pipe lengths as follows: Coming out of the boiler along to where it branches into the "front" and "back" mains, I measured right around 8-feet, with 6 elbows in the mix. From there, the "front" mains that I care most about (it's got the radiator in the thermostat room) I measured a total of 41.5 linear feet of pipe out to the main vent.

5.Show us pictures of the main vents you have.

They are both "No. 35 Vent-Rite". First two pics are the same vent, on the "front" main. The third shows the vent on the "back" main, hidden in the shadows in the top-left of the picture. But it's got the same "No. 35" label.

Now @Jamie Hall asked about how long it takes to heat up, so I ran an experiment this morning. Had the heat off for a few hours to let everything get cool, then turned it on (thermostat cranked to make sure it wouldn't be satisfied) and started a stopwatch:

• It took 7 minutes for the first horizontal pipe above the boiler (the "header"?) to get hot.
• Total 8m30s to reach the last horizontal pipe before it splits into the "front" and "back" main.
• Total 11m30s to reach the riser to the first radiator on the front mains, which I measured to be about 6 feet of pipe past where it the mains split. So from there to here, it took 3 minutes to travel 6 feet, it's traveling around 120 feet per hour.
• Total 14m45s to reached the riser to the next radiator, which I measured to be about 15'6" from the split, which took 6m15s, so it's averaged about 148 feet per hour up to this point. Which given my rough estimates could be about the same.
• Next point of interest for me is the riser to the dining room radiator, which is one of the cold ones, and the one in the thermostat room. Total time is 25 minutes when the main is hot immediately before this riser. It's traveled about 33'6" from the mains split to get here so the average time up to this point has now dropped to about 80 feet per hour, which I don't think I can blame on measurement error.
• There are another 7 feet of main past this riser before it reaches the main vent and the return. I let the heat run for another 65 minutes after this, and it never reached the end of the main. The hot crept slowly past that riser down the rest of the main, but didn't make it all the way within that time (at which point my family was tired of having the heat cranked, so I ended the experiment).

From doing this experiment, I can correct a claim I made earlier, and add a few more observations that are hopefully relevant:

1. The dining room radiator (first floor, front main, thermostat room) actually did got a little bit hot after about an hour. It's a thin-tube cast-iron radiator with 20 fins, and the first fin pretty much felt like a normal hot radiator, but the heat rapidly dropped off from there; by the 7th fin, it was pretty much room temperature. As the boiler continued to run for another ~30 minutes, even that first fin started cooling down noticeably.
2. On the "back" main, the first-floor radiators all have returns coming straight down from the riser. The main branches off horizontally to each of these, then goes into a sideways T, with one side going up to the radiator, and one side going down to the return. Two of these radiators never got hot, but as the heat reached their raisers, it seemed to be flowing into the down return rather than up into the radiator, to the point that the down return pipes were burning hot. The further I followed the return away from the radiator, the cooler it got.
3. The site glass seems to have the water line pretty well centered, and it doesn't look all cloudy with a head of oil like it did a few technician-visits ago. I'm not sure if they continued skimming, but they did lower the Hartford loop since then. The water level is now bouncing around a little bit, but by less than an inch I'd say.

And here are a bunch of pictures. If there's anything else that would be helpful, I'm happy to oblige, and will very much appreciate any help you can offer.

Jamie Hall

Can you take a very good level and measure for me the elevation differencee between the working water line and the horizontal (more or less) pipe down into which those radiator returns drop? I have a suspicion…

mattmia2

Where are the wet returns, the reaturns that are down low in relation to th water line of the boiler? they should be well below the water line. if they are not steam can flow through them and close that main vent from the end of the oppostote main before steam reaches the end of the longer main.

The mains should connect seperately to the header, they should not be teed together above the boiler.

The return being hot indicates either steam is flowing through it or hot water from the boiler is being thrown up in to it or maybe both. Looking at where the returns are I suspect it is steam and I'm pretty sure that is also what @Jamie Hall is thinking.

Waher

You have residual asbestos insulation on some of those pipes. Be careful to not disturb it.

The venting of the mains is insufficient. A single Vent-rite #35 isn't much better than a radiator vent, much less the capacity needed for steam mains.

The pressuretrol is set too high. The MAIN on the right should be lowered by the screw on the top of the pressuretrol case to 1.5 PSI and the DIFF on the left should be raised to 1 with its own screw on the top.

That Hartford Loop looks funky too me. I agree with Jamie that it probably isn't the at the correct critical dimension unless your measurement confirms otherwise.

bmearns

https://forum.heatinghelp.com/discussion/comment/1744383#Comment_1744383

I'm afraid I'm out of my practical depth here; my basement floor (as you can probably see) is very uneven, I'm not sure how to effectively measure the elevation difference between things so far apart. Happy for insight here, and/or anything else I can check to gather more data for your theories.

What I can say is that those down returns that are getting hot get hotter closer to the radiator, and cooler (relatively speaking) closer to the main return. That makes me guess they're hot because of steam fro the main, not hot water from the boiler. But, little do I know.

mattmia2

The hot water from the boiler would be thrown up in the main from the boiler because of incorrect near boiler piping and/or surging or priming of the water in the boiler, that is what is heating the drips down in to the returns if they are heating from the mains first early in the cycle. The near boiler piping looks very close to correct to me but there might be a small detail that is preventing it from working properly at all.

Both mains connected to a tee then to the header means that the steam will be slower to get to the mains because it will be colliding with condensate and possobly water brought out of the boiler with the steam collecting in that tee. I don't think that is your problem but it does slow heating some and waste a bit of fuel.

Jamie Hall

The easiest way to check level in a situation like yours is with a hose. Water seeks its own level. Therefore, the thing to do is to set up a hose with one end fastened at the water level in the boiler. Then with the other end raised, fill the hose with water and wander off to where you need to measure the level. Lower the raised end until water just barely comoes out of it, and there you are — that is the water level in the boiler, and you can easily meaure how high, relative to that, your pipes are — which is what you need to know.

Larry Weingarten

Hi, Here is a guide for making a water level: https://www.jlconline.com/deck-builder/garden-hose-water-level_o All you need is some clear tubing and hose connectors. This is good to use with two people, one at each end of the hose. It's easy and accurate.

Yours, Larry

Steamhead

Waher wrote:

"……The venting of the mains is insufficient. A single Vent-rite #35 isn't much better than a radiator vent, much less the capacity needed for steam mains……"

Agreed. That main should have a Gorton #2 vent. If the other main is of similar diameter and length, it should have the same.

You want the steam to fill the mains complete and quickly first, then when they close, the steam will rise into all the radiators at the same time.

KC_Jones

I concur with the others about main venting. It should take 5 minutes or less to go from header hot to the entire main hot. That slow delay shows a lack of main venting and can lead to some weird imbalance issues because the radiator vents are trying to compensate for main venting.

The boiler piping looks good except where the mains are tied together. That will make balancing the system difficult and it's not really proper. Mains should be tied into the header individually.

dabrakeman

Maybe it is an optical illusion but is your header smaller pipe size than the risers out of the boiler? Usually the equalizer should be smaller pipe than the header as well yet they look the same?

Another question. Was anything changed from the previous "working system" during the boiler install regarding the drip lines or returns?

Anyway, I would start with the main venting which as others have pointed out is woefully inadequate. Steam goes to the path of least resistance (easiest path to push air out of the system) and that should be initially just toward the main vents.

Jamie Hall

"Another question. Was anything changed from the previous "working system" during the boiler install regarding the drip lines or returns?"

More importatn: is the water level of the new boiler the same as, or very close to — within inches — of the old one?

mattmia2

does it bang? lack of venting won't cause water hammer.

water in the mains will also slow the progression of the steam

EBEBRATT-Ed

Yes they should have brought both mains down to the boiler seperatly as @KC_Jones mentioned. The piping looks good if it is sized right. and the boiler needs skimming

STEAM DOCTOR

Check the pitch in the header. Pictures can be deceiving but it seems like the header is backpitched.

STEAM DOCTOR

Also check the gas pressure and clock the meter. Possible that the boiler is under firing. Any possibility that the boiler is undersized??

109A_5

Hello @bmearns,

This pipe (its whole length) should have condensate in it all the time. Lowering the hartford loop may be counter productive in this situation (hose level verification). If the old boiler's water line was higher than the new boiler's water line this pipe maybe no longer full of condensate allowing steam to go where it should not.

Unless you realy want to heat the basement I would insulate all the pipes that normally would have steam in them. May help heat the living space faster since you are not re-heating the pipes as much with every heating cycle. Apparently they were once insulated.

Baking this wire is probally not good.

109A_5

Hello @bmearns,

Additionally, the hartford loop height should be referenced to the boilers normal water line per the boiler's install manual, not adjusted to try to solve some other problem. If that creates an issue with the wet return not having the proper level of condensate in it, one of three things to correct it, raise up the the boiler so the water line is the same as the old boiler was, lower the whole wet return system, or with some pipe create what is called a 'False Water Line' (probably easier and less expensive than raising up the boiler or lowering the wet return system).

Prove there is an issue with this first with a hose level, laser level, etc.

retiredguy

I am a little late to this discussion but this is what I would do. The first thing is to make sure that the boiler is sized properly for the job. I have seen many times where the heating contractor sized a new steam boiler based on the heat loss of the building which works for hot water but not for a steam system. For a steam system, you size the boiler to the steam requirements of the connected radiation without regard for the heat loss of the home. Someone should have calculated the BTU requirement of all the connected radiation. If that has been done properly and the boiler has been sized correctly then the boiler itself may have a problem. I would check the gas input of the boiler to make sure that the gas input is correct by "clocking the gas meter". Every service tech should know how to do this. If the gas input is correct and the combustion is also correct then the problem is with the connected piping and/or controls. If the gas input is not correct then that needs to be addressed. Check the gas input and adjust prer factory specs. One very rare problem is that the factory supplied the wrong gas orfices. A good service company would have done this already. If the company doing the service and installation can not fix the problem then it may be time to call someone else. There is a good list of contractors right on this site.

I mentioned the boiler sizing since I have seen this same thing happen on larger systems. One such case was the Indiana, Pa. county home. The job engineer siized the boilers based on the building heat loss instead of the connected radiation and the result was the same as yours. If your system worked and heated properly with the old boiler then I would check out the sizing of the new boiler before trying to make drastic changes to the heating system.

my 2 cents.

bmearns

Thanks, everyone, for the great input! I'll admit I'm a little overwhelmed, but I'm going to contact our heating company's project manager and work with him to create a plan for fixing this. It sounds like there are several key things to check and possibly fix:

1. Main venting seems obviously bad, it needs a vent that will let air flow through faster. I'm guessing this has always been the case, unless they for some reason decided to undersize the can when they replaced it to weeks ago. So it seems (to me) that this wouldn't be causing the problems we're seeing now, but it's certainly not helping our heating in general, and it's making it harder to figure out what is going on because it takes so longer for the steam to get to the problem.
2. Water may be stuck in the main or radiator, possibly due to things shifting during the install. This would slow the steam down, possibly even block it in some cases? And could be robbing the steam of its heat.
3. The wet return has a problem, it shouldn't be filling with steam. Sounds like the only reason this could happen is if it's no longer a wet return, which would be because it's above the water line of the new boiler. For now, I'm going to task the heating company to check this, but I don't feel like I can trust what they find, I can check with the garden hose method (much appreciate the great descriptions for this!).
4. The boiler should be checked to make sure the gas input is correct, and that it's sized correctly. I would hope that at least one of the many technicians who have been here would have checked at least the gas input as part of their debugging, but I'll definitely ask about it.
5. The Hartford loop should be installed according to the boiler's instructions, so I'll make sure they check this, given that one of their techs moved it after the install.
6. The mains should be branched from the header, they should both come straight from the boiler.

I'll get the pipes insulated as well, to be a bit more efficient with our heating.

Last note, some of you asked about banging. We get a little bit of it, but not much. I think it's usually early in the cycle (though bear in mind that our cycle lasts for hours because the steam moves so slowly). We also get a bit of "clunking" around the radiators as things change temperature and shift, which we've always had. I assume this is distinct from the water hammer effect of steam hitting condensate, which sounds more like someone is wrapping on the pipes with a wrench (or, I suppose, a hammer).

ethicalpaul

The wet return has a problem, it shouldn't be filling with steam. Sounds like the only reason this could happen is if it's no longer a wet return, which would be because it's above the water line of the new boiler. For now, I'm going to task the heating company to check this, but I don't feel like I can trust what they find, I can check with the garden hose method (much appreciate the great descriptions for this!).

I thought people were concerned that steam might get into the wet return. I don't share this concern. I'd focus on the venting. You don't want to overwhelm them either.

bmearns

https://forum.heatinghelp.com/discussion/comment/1744579#Comment_1744579

Thanks @ethicalpaul. I agree, I don't want to overwhelm (or distract) the heating company. I'm going to try hard to keep them focused on the dining room radiator first (the one in the thermostat room).

To clarify, I thought the concern was that the wet return is no longer wet, so the steam is able to bypass those radiators by going into the return and to the main vent. Do you have a different understanding of the concern about the returns, or do you just not think that's a concern?

Jamie Hall

At some risk of sounding like an idiot, why not take ten minutes to find out if that wet return is still wet? If it is — by at least a couple of feet — then you can go on and seek other problems. If it isn't, it may or may not be the primary problem — but it surely isn't helping. And it will take ten minutes, unless you have trouble finding a hose…

ethicalpaul

if the water level is visible in the gauge glass, the return must be wet, no?

dabrakeman

@bmearns Good plan but I would do #4 first adding to that the sizing verification of the boiler itself as well (total radiator EDR to rated boiler EDR) and then do #1 next. That Ventrite 35 is but a slightly above average radiator sized vent. Regardless of the return situation stam doesn't see the end of your main any different than just another radiator right now. Follow that with #2. Can get the hose test measures but if the return ended up above the water line I'm not sure how it is diferent than having drip legs below each radiator that tie back into a main extension (as in my system)? You are also vented at the end of the mains and not the end of the returns so even if the return was above water line I am not seeing what would bias the steam then to go into the returns and back to the main vent as the primary path of least resistance over the steam continuing down the large diameter main pipe to the main vent and closing it. The far end of that return system is still in water… 90 minutes of running and not getting steam to the end of the front main is indicative of some major issue and starting with 4/1/2 gets at things that should cause "you" the least pain first. I'm not saying don't do the hose test but I would do these other things before doing any major repiping. Just my 2 cents.

Jamie Hall

https://forum.heatinghelp.com/discussion/comment/1744588#Comment_1744588

Not if the boiler is too low relative to the pipe, or the pipe is too high. Seen it happen with boiler replacements a number of times. No on checks it, havoc ensues, and people spend hours trying everything else.

ethicalpaul

Maybe I'm missing something but looking at this, I don't see how steam could be in there with the water at this level (assuming the water stays near here during firing)

bmearns

https://forum.heatinghelp.com/discussion/comment/1744585#Comment_1744585

At the risk of also sounding like an idiot, the hose actually is the problem. I only have those "shrinking" hoses that automatically constrict, so if it's not under pressure from a tap, it will squeeze the water back out of it.

I'm not opposed to putting in some work here, but I've paid the heating company a lot of money to replace this boiler, so if they cocked something up in the process I'd generally prefer they spend their time and energy on it.