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gurgling sound

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chrisw_2
chrisw_2 Member Posts: 2
in THE MAIN WALL
My wife and I had a small addition added onto our 1927 house. We have a one-pipe gravity-based steam heating system. The proejct extended our heating out to the addition, adding a new radiator in the new bedroom, and a new radiator in the new bathroom. These two radiators make a gurgling noise when the system is on for about 30 minutes. The gurgling sound can be intermittent - stopping for 30 seconds, then continuing again, and stays that way until the system cuts off. The original portion of the house is over a basement and crawl space. The addition is on a concrete slab. The plumber hired by my building contractor to do the work extended a 1.25" hard copper line off of a riser for one of the existing radiators out to the addition. He ran one line, then made a running-t connection to split off a second line for the bathroom. The line is not insulated, and is sitting in the dirt just under the slab. I have since found a consultant locally to look at my system. With his advice, we have made some changes to make this better. First, we changed out the air vents on the radiators to 40s, to reduce the amount of air they were releasing (it was making a loud "breathing" sound before this in the addition). We also lowered the pressure on the boiler, and reduced the steam being inputted into the system by lowering the firing rate of the burners. This has helped, but not corrected the problem. The plumber says this was his first work with steam heat, and he thought he did everything right. He insists that there's enough pitch in the pipes to allow condensate to flow back to the radiator. The consultant says there's probably not enough pitch, that the lines should have been insulated under the slab, that there should be separate lines for each radiator, and that the connection to the addition should have been made to the main steam line, not off of a riser. The bottom line is that I've exhausted all of my known options to make this problem go away. I'm concerned the only answer will be to rip out the wood floors over the concrete slab of the addition, hammer out the concrete and relay the pipes all over again. Does anyone have any alternative suggestions or solutions that won't be so drastic?

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  • Mark Eatherton1
    Mark Eatherton1 Member Posts: 2,542
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    That's my stomach you hear gurgling...

    and as soon as I get back from dinner, I will address to the best of my capabitiites, your problem. Got pictures? Got drawings? Even in Paint will work fine here.

    Sounds like your consultant knows more than your plumber tho...

    ME

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  • Mark Eatherton1
    Mark Eatherton1 Member Posts: 2,542
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    Hmmm..

    After re-reading your original post, I'm leaning even more towards your consultants theories. The panting is definately a lack of insulation issue. The steam is collapsing back into condensate before it has a chance to get to the end of the main (the radiator). A few questions for you. How big are the radiators attached to the 1-1/4 main? Are the shut off valves completely open?

    I'm sure we'll come up with more questions as time goes on.

    ME

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  • chrisw
    chrisw Member Posts: 1
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    gurgling sounds

    mark,

    thanks for responding. the radiators are about 37 inches tall. the radiator in the bedroom is about 20 inches wide. the radiator in the bathroom is about 14 inches wide. the valves are completely open. we have alternated each radiator, shutting one down and then the other, to see if we can isolate the problem. the radiator in the bathroom is a little less noisy. this is the line that tees off from the straight run going out to the bedroom radiator.

    cw
  • Dale
    Dale Member Posts: 1,317
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    Counter flow system

    I think from your post that your addition is a counter flow system and that 1 1/4 inch pipe was used for the supply main. If this is so I'm not surprised it doesn't work too well. If the pipe extended to supply the addition is copper and uninsulated the steam will condense in the pipe before it goes too far, since the condensate comeing back blocks the steam coming up, the rads will pant. Counter flow requires a steeper pitch and I think the pipe is too small for counterflow but without the rad edr I don't know, I have never seen counterflow smaller than 2" but perhaps it's possible. What ever you do insulate the pipes first and keep the vent rate down. If you have a same sized tee feeding both rads I can just picture the condensate colliding there. You could as an experment just try the system with one rad supply valve open.
    Good luck
  • Mark Eatherton1
    Mark Eatherton1 Member Posts: 2,542
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    Stop gap measures...

    Unfortunately, I don't think there are any easy good fixes for your dilemma. Maybe Steamhead or someone else will jump in and offer further advice, but whats done is done and now you have to learn how to live with it.

    Installing a thermostatic vent valve on the radiators with a slow bleed vent will help alleviate the gurgling. Make sure the shutoff valve is completely opened to allow the condensate a clear path to drain back to the boiler. If you have a set back thermostat, you also might try limiting the deep set backs to 5 degrees F or less to lighten the condensate load associated with cold start up. I've had success doing that in a couple of situations similar to yours. Also, make sure your operating pressure is less than 2 PSI.

    Let us know how you make out, and good luck.

    ME

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  • Steamhead
    Steamhead Member Posts: 16,842
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    Thanks, Mark

    Chris, I'm afraid I have to agree with your consultant. Copper on steam pipes is a no-no, and you're losing a lot of heat into the surrounding dirt, especially if it is moist.

    You might try looking at your main vents to see if they're big enough. Sometimes installing the right vents near the ends of steam mains will slow the steam velocity in runouts and risers, which would let the condensate drain back better. If you measure the length and diameter of your steam mains, and tell us what vents are on them, we can advise you further.

    If this doesn't work, however, you will have to repipe that runout. Use black steel, insulate it, and don't bury it in the dirt or it will rust out.

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  • chrisw_2
    chrisw_2 Member Posts: 2
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    gurgling sounds

    steamhead...

    the steam mains are 3" in diameter, i think (they're rapped in asbestos, which is sealed in a few layers of latex paint). i'm not sure what you mean by the length of the main lines - from where to where?

    my heating consultant also had some thoughts on this. upon his recommendation, i put 1/2" by 3/4" 4A main vents on both of the main lines, and on both of the main returns. i believe he called these "quick vents" to allow the system to vent out as much air as possible before sending the steam through the system.

    we also lowered the pressure on the system from 2 psi to about 0.8 psi. these helped, but certainly didn't correct the problem.

    would it be possible/workable to convert this line and the two radiators (to the addition) to a hot-water based system using my same steam boiler? i'm just trying to think outside of the box here...

    cw
  • Steamhead
    Steamhead Member Posts: 16,842
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    Length of steam mains

    is measured from where they come off the boiler to where they end. If they're 3-inch that must be a pretty big house! If you're measuring the outside diameter of the insulation, subtract 2 inches since the usual insulation was 1-inch thick, and this will give you 2 extra inches- one on each side.

    I'm willing to bet you need bigger vents than those Hoffman 4A units. Although they are called "quick vents" they don't vent very quickly! The 4A really only works well on very small systems with less than 20 feet of 2-inch pipe or so. I remove these vents all the time and install larger ones.

    Lowering the pressure is always a good idea- your system was designed to never need more than 2 PSI, and that was on the coldest day of the year. If you have the standard gray Honeywell Pressuretrol, the scale on the outside is where the burner comes back on. Inside there is a white wheel that adjusts the differential. Turn the power off before removing the cover, and rotate this wheel until the number 1 points to the front of the unit. This will lower the point at which the burner cuts off as far as it will go.

    I wouldn't try to run the new radiators with hot water- it would be more complicated and you'd still have to replace all the piping. Stick with the steam.

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