2 pipe system-banging noises

LFsuper

Hi,



This has probably been posted here many times before but here it goes. ..We have a 2 pipe system in a large multifamily building. On one particular line there is a constant tapping noise from the riser. Sounds like more of a constant drip. I would not say it is a loud banging noise but a constant irritation.



Recently we raised the pressure from 3 pounds to 5 to help sustain movement of steam and retain heat in the pipes. We have baseboard heaters with the boiler on 30 min cycles.



Thanks!

jpf321

does it ever...

stop tapping?



needing to raise your pressure that high certainly points to other system problems...in have ben in 100+ unit buildings (600+ rads) running@ 2-3 psi...

BobC

Turn the pressure down.

That pressure is much too high, if they can heat the Empire State Building with 2-3PSI an apartment building will do just fine with 1.5PSI maximum. Higher pressure makes everything worse but it makes the people supplying your fuel very happy.



Has this system been noisy forever or did it start after some work was done on it? Have they checked the main air vents to be sure they are working? A lot of main vents do not take kindly to anything above 3PSI - in fact they lock shut and they can't work as they were designed - and then you pay the fuel company in spades.



Bob

LFsuper

Thank you

Most helpful-

LFsuper

Thank you

Very helpful also

Jamie Hall

Not to put too fine a point on it...

as BobC says, at 5 psi you are either in serious trouble or are going to be shortly.  You will trash your vents -- the little floats collapse, and then they are toast.  They don't even make decent paperweights.



Turn that pressure down to 0.5 cutin 1.5 cutout, and then set about fixing whatever problems there were that you thought could be cured by higher pressure. 



For starters, I would check all the main vents on the steam mains or the returns, whichever they are on.  It is possible -- we can hope -- that the high pressure hasn't damaged them, but I wouldn't count on it.  Make sure that they are adequate in size, and that they are venting properly.  My rule of thumb on that is that steam should travel in the main, to the far end, at not less than 15 feet per minute -- that is, for example, if you have a 75 foot main, if it is adequately vented it should take less than 5 minutes from the time it is hot at the boiler to the time it is hot at the end.  Anything more than that and you need more main venting.



The same principle applies to risers, but to a lesser extent and only if there are a number of floors.  Normally in a two story building you won't need riser vents.  You might in a three or four, and almost surely they will help in five or more stories.  They would be like the main vents, but placed at the top of the risers.



You do have insulation on all your steam mains, don't you?



And keep us posted on what you find!

LFsuper

Thanks

It was our boiler company that raised the pressure, To be honest I was not 100% confident in his decision to do so and probably should have said so... I will bring them back asap and re-adjust. They must be related issues...

jpf321

let me guess ...

your "boiler company" is also your "fuel supplier" .. I wouldn't call them back to undo what they did .. simply readjust it yourself .. send us a picture and we'll explain exactly how to do it .. if you have more than 1 "pressure" control .. please send pictures of all 3 controls. do you know what prompted him to turn it up? perhaps your pigtail needs cleaning .. but now that I think about it .. if he raised it b/c it was tripping off .. then your pigtail is likely clear.



where are you located??? .. perhaps you will be in need of a non-fuel-selling steam pro in there to straighten you out a bit and get you going on the right road towards quiet efficient comfort.

Charlie from wmass

Yes related to pressure

I would bet on the noise being a trap trying its best to stop way too much pressure. this is why pressure is the first red flag here. drop the pressure then find that bad trap. At least it should be located near that riser. It may also be a trap stuck closed and the condensate is dripping back from its radiator. Again get the pressure right them proceed. Any time the answer is turn up the pressure it is wrong, except when it is right. But here is not that case of it being right. 

LFsuper

Thank you all

Had a good tech here last night, I am kicking myself for not spotting it but our indoor heat sensor on the return line is shot. it is reading 40 degrees below actual temp. We are having new sensors installed today. He also took the pressure back down, Although I am still hearing the "drip sound" I am sure my problem now lies with a faulty trap. Would it made a difference if somebody above us being fed off the same riser has their valve radiator valve closed?



Thanks again