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Vent Spitting & Water Hammer in Condo

This is my first winter in a 25 unit prewar building (large building, formerly commercial) with a single-pipe steam system. I have two large radiators in my unit with adjustable vents and have a problem with both, although the smaller (about 4 ft) radiator is the most trouble. I have good pitch and new vents on both, so I don't think those are the culprits.



Essentially, if I turn the Vent-Rite to a high enough setting to get the radiator hot over a heating cycle, the result is water hammer and eventually the vent spitting water toward the end of the cycle (this is a new vent so that is not the issue). The setting to heat the whole radiator is not even the max (8) but only 4 or 5.



If I adjust the vent down to about 2, the hammer is almost entirely eliminated and there is no spitting, but less than half the radiator heats during a full cycle so the room stays too cold.



My super advised me to bleed the radiators, but I've done a fair amount of research as I understand it bleeding doesn't make any sense on a steam system.



Assuming the building piping is good, I gather from research that the building system might have either too wet steam or too much pressure. Does that sound right?



I can also hear what sounds like supply valves being opened and closed a lot in the unit above me - if they are misusing those in an attempt to control the heat could it have an impact?



I'm confused how to get this resolved, especially as far as convincing the condo to hire anyone to look at the boiler settings since I haven't heard anyone else with this issue. If it matters I am on the second floor, so I am essentially the very first apartment in the line of units receiving steam as it moves up.



I truly appreciate any advice as to how to proceed.

Comments

  • ChrisJ
    ChrisJ Member Posts: 16,231
    Pitch

    How is the pitch in the radiator?  Is it pitched back towards the pipe?



    Please post some pictures if possible.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • NYCSteam
    NYCSteam Member Posts: 10
    Yes

    Sorry edited to clarify the pitch is good on both - I don't have access to the boiler, are just radiator pics helpful?
  • ChrisJ
    ChrisJ Member Posts: 16,231
    Yep

    It will help just to see how the radiator is piped and what the overall situation looks like.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • NYCSteam
    NYCSteam Member Posts: 10
    edited December 2013
    Pics

    pics - thanks
  • Mark N
    Mark N Member Posts: 1,115
    Venting

    If you vent a rad to fast the condensate might not be able to drain out again the steam entering the radiator. Check the hand valve make sure it is all the way open.
  • NYCSteam
    NYCSteam Member Posts: 10
    thanks

    Valve is open all the way - I did read not to vent it too fast but shouldn't I be able to vent enough to heat the full radiator over a cycle? As noted I can't do that for now, only about half or the hammer and spitting happen
  • ChrisJ
    ChrisJ Member Posts: 16,231
    Venting

    Depends,



    I have vents on my radiators which are much faster than what you are using. However, pressure plays a huge roll as does how the radiator drains. We can't see where that pipe goes and whether it goes into a 90 deg elbow inside the wall or what the deal is. If that is like that for any length it will cause problems.



    How long is a cycle right now where the radiator only heats half way? 15 minutes? 30 minutes?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • NYCSteam
    NYCSteam Member Posts: 10
    15

    I think it is 15 or less but would have to time it - should I just try asking if they will make it cycle longer for starters?



    Am I correct in telling the super that you don't need to "bleed" steam radiators?



    Thanks
  • ChrisJ
    ChrisJ Member Posts: 16,231
    Bleeding

    No, you don't bleed a steam radiator.



    A 15 minute cycle shouldn't heat that radiator, at least not in my opinion. It would take my system over an hour to heat a radiator that size.





    However, you did say the room stays cold?
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • NYCSteam
    NYCSteam Member Posts: 10
    Will ask about cycle

    Thanks I don't want to sound like I haven't put in effort in research, just double checking before I tell him so :-)



    The radiator is definitely very hot for the portion that gets steam, it's just not enough heat for the room (so it stays around 66-67 when it's 25 degrees outside whereas I'd like 72 or above of course...)



    I'll ask about the cycle and go from there
  • Mark N
    Mark N Member Posts: 1,115
    Radiator Size

    The radiator should be sized to meet the heat loss for the room on the design day. That very cold day is the day the rad should heat completely across. It sounds as if the rad might be undersized for the heat loss of the room. If the rad heats half way across on a 20 to 30 minute cycle that should be plenty.
  • ALIGA
    ALIGA Member Posts: 194
    Maid of mist adjustable

    I recommend buying one of those to see if it improves the heating.
  • steamedchicago
    steamedchicago Member Posts: 72
    target temperature?

    Also ask what the target temperature is.  If it's 68 (pretty likely), don't be surprised if the response to "it's cold" is "buy a space heater" or "put on some clothes" or "move.".  
  • MDNLansing
    MDNLansing Member Posts: 297
    How Much

    How much of the radiator gets hot? 1/4 of it, 1/2 of it? On a 15 min cycle, a radiator that size probably won't heat much more than 1/2 way. You could try putting a higher cfm Gorton vent on it. That would allow more air to escape and the steam to distribute more evenly in the radiator. However, that will probably make the water and hammer worse. The thing is, the steam mains need to vent fast, but the radiators need to vent slow. You need all the air to leave it, but at a slower rate than the mains. Increasing the venting will probably get it hot, then squirt water all over.



    If they can increase the cycle time, that would be a good place to start. However, the longer the boiler runs the higher the fuel bill. They might not be willing to increase the burn time for 4 more degrees in one room of one condo. Never hurts asking though.
  • sounds like

    sounds like your bleeding the air and getting water hammer and only part of it is getting hot? might be waterlogged if u have too much water the steam wont heat up the excess water how old is it maybe its got 10 tons of crud in it as well stopping drainage
  • NYCSteam
    NYCSteam Member Posts: 10
    How do I remove the crud?

    That is the case - the radiator is quite old, do you have any advice on removing buildup or a link to a guide for doing so? Thanks
  • NYCSteam
    NYCSteam Member Posts: 10
    1/2

    About half gets hot.



    That is exactly my problem - if I vent faster it all gets hot but inevitably spits.
  • JohnNY
    JohnNY Member Posts: 3,287
    ?

    Is this in Manhattan? Brooklyn?
    Contact John "JohnNY" Cataneo, NYC Master Plumber, Lic 1784
    Consulting & Troubleshooting
    Heating in NYC or NJ.
    Classes
  • mcsteamy
    mcsteamy Member Posts: 77
    edited December 2013
    Hmmm...

    Lots of advice being thrown around, and as far as I can tell, very little of seems to pay any heed to the facts and physics at hand with one good exception:  Chris's comment that the feed pipe could be causing a problem.  Too bad all the pros are so busy right now!  Ah well, they gotta earn a buck, too.  



    First things first:  A Vent-Rite #1 wide open vents only .125 CFM at 2oz of pressure.  It is a very slow vent.  Akin to a Gorton #5, which is not a large vent at all for a radiator that size.  You should be able to run that vent wide open without water hammer.   If your room is cold, the vent is not too big.



    Second:  It should not necessarily take an hour to heat a radiator that size in a large building.  My office building with a Paul vacuum system would heat that in about 5 minutes.  In my house, that would heat in about 10-15 minutes, or less with a monster vent on it.



    Third:  Radiators can and should heat all the way across on a day that is not frigid.  The key is that they will not necessary STAY this way.  Even when hot, a radiator is still condensing steam and cranking out heat.  On the coldest day of the year, the radiator will stay hot all day long.  In November, it might just barely fully heat, and then slowly cool off since the building will not be calling for as many heating cycles. 



    Fourth:  Ask the super how high he is running the boiler pressure and tell him to CRANK IT DOWN if he has it over 2 pounds cut out.  This could easily be causing some of the hammer. 



    Fifth:  if there is, in fact, a long horizontal run-out to that radiator, it could have sagged or otherwise be improperly pitched.  This is the most likely cause of your banging.  You need to see where that pipe goes past that wall and put a level on it.



    Sixth:  If the people upstairs are, in fact, using the radiator valves to shut off the heat, they might be causing condensate to accumulate, which could cause banging if somehow it all dumped back into the run-out serving your radiator.  However, since this banging seems to happen all the time, this seems unlikely.



    From the description, water is building up where it should not be, and steam which ought to be moving at a perfectly reasonably velocity and pressure based on your venting is  picking up that water and slamming it into a pipe.  It stands to reason that condensate it in that pipe which should not be.  This sounds like bad pitch somewhere, or excessive steam pressure that is holding condensate in the pipe.  Guesses, but places to start.  Check the pitch on that pipe, and find out the pressure on the boiler, then report back.
  • NYCSteam
    NYCSteam Member Posts: 10
    Thanks

    Thanks for the great help - the super keeps telling me to bleed the radiators when I ask him the pressure unfortunately...



    For the pipe running from the radiator - it runs straight through the wall into the adjoining bathroom. Unfortunately a wood bench was built around it (in a shower) but I can see through the slats with a flashlight (but a picture isn't very feasible). The pipe runs about 5 feet and has a curved joint connecting to the perpendicular steam pipe. Although I can't get a level on it I can eyeball that there is definitely a decent subtle pitch on the pipe downward toward the riser, which I assume is exactly how it should be. The pitch and joint look pretty intentional and I can't see how it would be sagging anywhere. Unfortunately I'd have to tear apart this wood built-in to get full access, and given the visual and the other unknowns about the system issues I'm not sure if I want to go there unless I know the building system is dialed in just right. Other than this I've got to think it's the amount of pressure running in this system that's the issue...



    I appreciate your help. I'm sure heating half this radiator is pretty good for a Vent-Rite at 2-3, but again my issue is anything more leads to spitting and noise. Even now I get a couple knocks at the start.



    I guess I've got to find out the pressure on this system and if it's good I'd have to tear apart my built-in to check the pipe for sure...
  • ALIGA
    ALIGA Member Posts: 194
    buy another valve

    get a maid of mist adjustable, i am sure that will fix the spitting. its a 12 dollar fix.
  • NYCSteam
    NYCSteam Member Posts: 10
    edited December 2013
    Confused

    There was a worn out hydroscopic valve on there I already replaced with the Vent-Rite in hopes of tweaking the vent rate down enough to help the problem. I am familiar with the product you are talking about but I'm not clear on why it would produce a result different from the Vent-Rite? I assume if there is too much water hitting the vent for the Vent-Rite to properly stop spitting the Maid-O-Mist would have the same issue, or else would only not have the issue if I used a small enough fitting among the choices to keep the venting really slow and end up right where I am now. Either way can you just clarify why I'd have a different result with that product? Thank you!
  • ALIGA
    ALIGA Member Posts: 194
    my experience with the maid of mist

    they dont spit, if water hits it, they close.
  • ChrisJ
    ChrisJ Member Posts: 16,231
    Spitting

    In my opinion spitting is usually caused by condensed steam in the vent spraying out due to the pressure in the radiator or water from condensed steam dripping past the vent and being pulled into it by air rushing out. No vent will close under these conditions.



    A Gorton or Maid-O-Mist (I'm a Gorton man my self) may have more volume inside the valve housing allowing less spitting but I wouldn't guarantee it.



    Lowing the pressure, which you cannot do would likely stop it.



    My opinion right now is your only option is to vent slower, which is what you're doing. The fact the super keeps telling you to bleed the radiator proves he has no clue how to work on a steam system and shouldn't be in charge of it.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
This discussion has been closed.