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Water out selected radiators

Hoping you folks can help. Long story, but please bear with me…
Been in an old house with oil-fired, single-pipe steam heating system for 10 years. System always serviced regularly by our oil company. It’s a drafty old place, but system always seemed adequate for the most part.
That was until a year or so ago when I noticed the water level was over the top of the sight gauge. Service guy examined system and suspected the automatic water feed was not closing off completely. He drained off some water to normal level and put some stuff into the boiler that turned the water green; said it was a chemical to help loosen any residue, etc. that might be hanging the feeder up.
Problem persisted. I was keeping an eye on the water level and periodically would see it overflow the boiler again. Service guy said it looked like I’d need to replace the automatic water feed but, rather than do it now in the middle of winter when they were busy, he’d just disconnect it and close the valves on either side. He said if I saw the water level go down any significant amount, I should open the manual bypass valve to add a little. I asked him if that was OK to do while the system was hot and he said that’s what the automatic feeder did.
So I did as he suggested to limp through the winter. But the water level was erratic. Sometimes it would be low, so I’d add a little; but other times it would actually be over full and I’d have to drain some off again. The service guy said it was likely the old-style gate valves in that water feed manifold were leaking and the whole thing should be replaced along with the automatic water feed.
I got through the winter and shut the heat off for the season. Mid-summer, I find the boiler leaking. A check of the overflow valve, attached piping, etc. showed no leaks – it was coming from the boiler itself. I removed the covers and it was clear it was leaking in several spots. Service said I’d need a new boiler. This seemed odd as it was only about 17 years old, but they said that was not unusual. Looking back, I suspect I cracked the boiler by listening to them and adding water to a hot boiler. Either that or the frequent additions promoted just enough corrosion to do-in an already compromised boiler (we’re on well water, which I know can be hard on a system, even though we do have a softener).
Between their lackluster attitude, the high price they quoted me for replacement and my general lack of confidence in them, I went to another company that had more experience with steam systems.
They installed the new boiler, including all new low-water cutoff and automatic water feed, valves and manifold. They also changed a number of radiator and main line vent valves. It wasn’t yet heating season, but I ran it periodically at their suggestion to check for any issues and they skimmed it a couple of times to get any crud out of the system. All seemed normal until one evening when I had just turned on the system, I noticed the water level was above the sight glass. Worse, I found two radiators spraying water out of their air valves. Thankfully I was there to catch them before the flooding got too bad and we had a real disaster. I shut off the system and called the installer back in.
The odd thing was the way just those two radiators had filled up. There are three main branches of the steam system once it leaves the boiler, each of which serves radiators in different portions of the house. The two that had overflowed were on the branch for the front of the house. That branch has three legs coming off it: one feeds a single first-floor radiator, a second runs up to feed two second-floor radiators and the third feeds a first-floor radiator and a second floor radiator. It was these last two that had overflowed – yes, one on the first floor and one on the second.
I thought there must be a blockage in that leg that allowed steam through, but slowed the condensed water from flowing back, thereby filling up the pipes/radiators of that leg over time until they overflowed. In the meantime, the boiler water level wouldn’t be replenished, so the automatic feeder would add more. Then, when the system was shut off and the water in the pipes had time to seep back down, the boiler would be over-full again. This was consistent with what I was seeing.
My installer said that was unlikely. He had never heard of a blockage in the actual steam line and that any blockages usually occurred in the return line, since it was the lowest point of the system. I pointed out, though, that the return line was down in the basement. If it had plugged, all three of the legs off that branch would have filled with water and the other first-floor radiator would have been spitting water before that second-floor one did.
But he felt that wasn’t necessarily so; that it could have to do with the orientation of the piping, etc. So he removed the return line, expecting to find it clogged. It wasn’t. He also flushed and skimmed the whole system again just in case there might be some remaining crud clogging things up. I’m again running it periodically while keeping a close eye on that water level and those two radiators that had leaked, but I have no trust in this system at this point. We’re heading into cold weather and I can’t be confident to leave the house with the heat on for fear of coming back to a flood.
Do you think it’s possible that the actual steam line for the leg that serves those radiators could be plugged? If so, can it simply be snaked out in some way? Any other possibilities? Many thanks in advance.

Comments

  • dopey27177dopey27177 Member Posts: 401
    Sounds like you have a thing called condensate time lag.
    Basically that means the the condensate from the system takes to long to return to the boiler. This allows the auto feeder to install water into the boiler. When the condensate returns it mixes with the feed water and you have a flooding condition.

    Need pictures of the basement steam, return and near boiler piping to try to ascertain the problem.

    Jake
  • Jamie HallJamie Hall Member Posts: 13,412
    May well be slow condensate return. The autofeeder should have controls (usually dip swirches) which can be set for the amount to feed and the time delay. Set it for the lowest amount -- usually one gallon -- and the longest delay -- usually 10 minutes. Do NOT use the option to fill until the level comes up. That looks attractive -- and causes much mischief.

    On the leaky boiler -- probably adding fresh water regularly accelerated the problem, but 17 years isn't unheard of. I doubt you cracked it. However having said that, you also mentioned that you have a water softener. Do NOT, repeat NOT, use ion exchange softened water in your boiler. Take that feed from before the water softener. Ion exchange softened water is very corrosive, and will do in a boiler in short order.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • transplanttransplant Member Posts: 12
    Thanks to both and I will get some pictures to post. Yes, I believe it is condensate lag but the question is why it only recently started happening and why only on one branch off of one main leg of the system (?). To me, that suggests a clog and not in the return line for that whole leg (because the other radiators that are lower and closer to the boiler don't over-fill). It suggests a clog in the actual steam line that feeds the two affected radiators that have filled, no? Is that unheard of, i.e. the steam feed line clogging to the point where it allows some steam through to heat the radiators, but is clogged enough to slow/stop the condensate from coming back down, over time filling the lines and the radiators?
  • Jamie HallJamie Hall Member Posts: 13,412
    A clog in a steam line is sufficiently unusual that it would certainly be worth documenting -- in detail.

    On the other hand, a radiator valve which is only partly open, or where the disc has finally fallen off the stem and is blocking or partly blocking the opening, is sufficiently common to be routine.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • mattmia2mattmia2 Member Posts: 1,872
    edited October 19
    Or piping that isn't pitched properly or has a dip in it that is collecting condensate.

    Is this one pipe or 2 pipe?
  • transplanttransplant Member Posts: 12
    Mattmia2, this is a single-pipe system. Jamie, the radiator vent valves are new. Tried sketching out this leg of the system, but tough to get the turns, etc. into a 3-D drawing, so below is a simplified version. Again, since radiators #4 and #5 on the drawing are the ones that are spraying water out their vents, it would seem that they might be clogged where they come together before attaching to the main steam line.
  • mattmia2mattmia2 Member Posts: 1,872
    It is much more likely that the return is clogged holding the condensate in the end of the main where it gets picked up by the steam going up to those 2 radiators at the low end of the main but it isn't completely clogged so the condensate slowly makes its way back to the boiler but not as fast as it is produced. It may also affect operation of that vent forcing the system to vent through radiators 4 and 5 instead of the main vent. Are there signs of moisture around the main vent like white crusty deposits?
  • transplanttransplant Member Posts: 12
    Here are some photos. First is the back of the boiler. Second is the main steam leg looking away from the boiler. The feed for rad #1 is going off to the left. The feed for rads #2 and #3 is in the background against the wall going into the ceiling. To the right at the end of the main is the tee where the two feeds for rads #4 and #5 branch off. The third photo is a close-up of
    that junction where #4 and #5 branch off and where I'm suspecting there might be a clog. You'll see the main air vent and the return line below.


  • Jamie HallJamie Hall Member Posts: 13,412
    That is possibly the worst location for a vent I've seen in quite some time. Barring any other problems, that vent could be almost anywhere else and be more useful -- assuming, given its location, that it still works at all, which I rather doubt.

    And I completely agree with @mattmia2 -- the most likely problem given that geometry is that that return line is partly plugged. It wouldn't take much of a plug there to cause condensate to collect at that location and get forced up into those risers.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • transplanttransplant Member Posts: 12
    Aren't main line vents always placed at the end of the line like this?

    Also, we did remove the return line section that runs down along the floor, as the installer said that would be the place where it would clog. But it was clear. And if the return was blocked somewhere, wouldn't it cause that whole portion of the system to fill with water and leak out of the other radiators, especially the other one on the first floor?

    I think I also misunderstood your earlier suggestion that the disks may have fallen off in the valves. I thought you meant the air vent valves, but I guess you meant the valves that feed steam into the radiators, right? Tried to take the tops off them to see if that had happened, but they are really on there? Any tricks for getting them off?

    Thanks to all for the help and patience. Trying to reason through this one.
  • transplanttransplant Member Posts: 12
    Mattmia2 - Sorry, didn't see your earlier comment before my last reply to Jamie. There were no crusty white deposits around that vent at the end of the main, but it was all covered with insulation with just the vent sticking out before I took it off for this photo.

    From your comment and Jamie's, sounds like the next step is to take apart that return and ensure it's clear, then at least replace that main vent with a better quality one (rather than the H.D. version currently on there).
  • transplanttransplant Member Posts: 12
    Forgot to mention: Just to explore my earlier thought that there might be a clog where those two risers for #4 and #5 come together to meet the main, I took the vent out and probed up in there with a stiff wire. Didn't seem to hit any obstruction and it moved around pretty freely, so don't think it just pushed a small hole through one. That's what led me to think perhaps the disks did fall off the steam feed valves for these two radiators, though it would seem strange to have it happen to two at once.
  • mattmia2mattmia2 Member Posts: 1,872
    Did you do anything to ensure the vertical portion of the pipe and especially the tee or ell at the bottom of it were clear? It could be blocked somewhere in that area. The water isn't backing up in to the radiators directly, as the steam moves over the water it carries some water with it and that is the water that is getting in to the radiators.

    Does the system bang?
  • Jamie HallJamie Hall Member Posts: 13,412
    Yes, main vents are place at or near the end of a line. They are NOT placed in a tapping on a T right smack dab at the end of the line, near the bottom of a the leg of the T on the other side. Any water at all flying along that steam main will go right into the opening for the vent.
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • transplanttransplant Member Posts: 12
    Mattmia2 - are you talking about the vertical portions of the risers to radiators #4 and #5, or the vertical portions of the return line or both? And I hear what you're saying about the steam picking up the water, but it sure seems like the radiators themselves are full, given the steady stream of water (not just spitting) shooting out the vents... Have some banging in other parts of the system, but not on these risers/radiators, at least it doesn't seem so.

    Jamie - I get what you're saying about that main vent. Understand it should ideally be after the last outlet to a radiator and before the final elbow, mounted up high. Problem is there is no place in the piping to do that. The tee for the last two radiators is the end of the line, with the other side leading into the return. Also, the vent that is on there is a 1/8" angle vent that I gather is too small (more like a radiator vent). So sounds like the system should be improved.
    All that said, however, it was working for the first 8 years or so that we were here, so this trapping or backing-up of condensate that is now coming out of those 2 radiators must be the result of something having changed, like a clog, etc., no?
  • mattmia2mattmia2 Member Posts: 1,872
    The piping and tee that are on/near the floor and the pipe coming up off that pipe or possibly the convoluted elbows just off the bottom of the main.

    The valves on the radiators are all the way open, right?
  • Jamie HallJamie Hall Member Posts: 13,412
    "All that said, however, it was working for the first 8 years or so that we were here, so this trapping or backing-up of condensate that is now coming out of those 2 radiators must be the result of something having changed, like a clog, etc., no?"

    Always a good way to start! So think back -- what did change? What work was done?
    Br. Jamie, osb

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • motoguy128motoguy128 Member Posts: 182
    main vents can be anywhere on the main, but are most effective at the end of the main. But they will still work further upstream to supplement the main vents.

    I;ve added vents by drilling and tapping the top of horizontal elbows 1/4” flows a fair amount of air. Vertical Varivents work descent as main vents.
  • BobCBobC Member Posts: 5,128
    To check for a possible clogged return path, remove the main vent and devise a method so you can feed a gallon of water into that open pipe. Before adding the water mark the water level at the sight glass so you can see if the boiler water level changes.

    If the water does not appear at the boiler in a few seconds you know you have a problem.

    Bob
    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
    mattmia2
  • transplanttransplant Member Posts: 12
    Mattmia2 - We had the piece of the return that runs across the floor off and it was clear. Will see about checking the rest of the return.

    Jamie - That's the thing; nothing was changed -- radiators, vents, lines; nothing. As noted at the start, we did just have a new boiler put in, but this over-filling situation was going on with the old one. Just didn't realize it at the time; thought it was a faulty automatic feed.

    Motoguy - Problem is, on my current set-up there is no vertical portion past the last radiator riser to drill/tap. It's a tee, with steam coming in one side, the last riser out the other and the return going out the third. Someone had drilled/tapped the side of that tee and put in a 1/8" vent. Think I could enlarge it and put some nipples and an elbow to mount a larger vent up higher above the main?

    Bobc - You read my mind. I did exactly that, though I didn't add a full gallon of water -- not even a quart. Didn't see a rise on the sight glass, but might not have been enough to detect. Seemed to go down the return, but may be a clog down far enough for the piping above it to hold that small amount. But DID find that, after I put the vent back in and started the system, as it got hot it started leaking water out THAT vent (at the end of the main), suggesting that the water may indeed have been sitting at the mouth of the return and was now being pushed out as the line vented. I'll go back and do it again with more water to see if I can verify a clogged return.

    Thanks again to all for sticking with me on this.

  • transplanttransplant Member Posts: 12
    Update: took Bobc's suggestion. Marked the sight glass water level, took out the vent in the main, poured in a gallon of water. Didn't back up; seemed to go down the return just fine and sight glass water level rose accordingly. So, a plug in the return is not the culprit.
  • transplanttransplant Member Posts: 12
    Further update: Did same as above, but this time from one of the problem radiators. Disconnected it at the union; made sure steam valve was open and the disk hadn't fallen down and blocked the inlet. Then poured a gallon of water down the pipe. Went without any backup and ended up in the boiler as it should have. Can't check other problem radiator since that union requires a bigger wrench that I don't have. But suspect it will also drain fine. Now I'm really stumped. If there are no blockages in that leg of the system, the pipes and radiators all have proper pitch and the radiators have new vents on them, why am I getting water spilling out of those vents when things heat up?
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