Rattling heater pipes

[toledo-nate]

First, Thanks for taking time to look at my question.

Alright, heres the situation. I have a 16 two bedroom apartment building using a central boiler to heat the apartments. The tubing ran through out is the old gray Polybuetelene (PB) connecting to baseboard radiators (alum. finned copper pipes). On the top floor of an end apartment I am hearing a pipe or something "vibrating" "rattling" inside the wall. The best way that ive found to describe it is like a cabinet door closing and boucing against the frame of the cabinet. I only hear it about every 5 or so min. Its very random on loudness and when it happens. I tried bleeding air out of the line from a small bleader port but just got water. Im stumpped and so is my parts house. Any suggestions. Thanks again for your help.

P>S> If anymore info is needed please let me know.

-Nate

[Diceman]

Air in there, call someone.

[Moose]

zone valve cycling?

[Senior Tech]

Air...polybutylene pipe was also the subject of a class action lawsuit due to random leaks for no reason among other things, google it and you should find the info.

[markwolf]

That old grey pipe has no oxygen barrier.Go check out rehau's site or wirsbro's.Pex intended for domestic water use will give you air problems until it is replaced with pex rated for heating use.

[propmanage]

A control valve at that location or any isolation valves. Oxygen in this system as they mentioned may have rusted or broken something that moved in the pipe line. Do you treat the system with chemicals?

[toledo-nate]

The only control valve on the system is a hand operated valve that moves an insert in and out to control the flow.

There currently isnt any chemicals in the water and havent been in years from what I know of. Im Working on changing that when the weather warms up enough to flush the system.

[willard3]

You know, complain as we might about plumbing codes, NY never allowed polybutylene piping and I'm glad they didn't.

[toledo-nate]

Would not having air in the expainsion tank cause this problem also?

[Senior Tech]

Originally posted by toledo-nate
Would not having air in the expainsion tank cause this problem also?

Ummmmmmmmm...I hope there's air in there...

[toledo-nate]

Well I found out that the expansion tanks didnt have any air in them (40 gal steel tank with an airtrol valve). Also replaced the air bleeders on the boilers. Hopefully this takes care of it.

[deltatee]

check pressure regulator, pressure gauge (I.e. give it a tap with the Maglite!) ensure there is air in the expansion tank. Can you connect hose from city water supply to boiler drain and flush system through to remove airlocks? Hammering is always a problem with air and/or flow. What is aquastat set at?

[sigma]

Toledo
Air traveling through pipes and baseboard heaters usually creates swooshing or gurgling sound.
Your description suggests a water hummer. Since there are no fast closing zone valves in this system I believe that you are looking for the problem in a wrong place.
You say that noise is in the wall. Maybe there are domestic water pipes in this wall that are loose. Now all you need is a toilet with Fluid Master fill valve and leaking flush valve. This would explain 5 minutes intervals.

[toledo-nate]

Awesome brainstorming! Thanks for the idea. I will definately look into that.

[al o]

maybe the piping is in contact with a floor joist or stud and your hearing expansion & contraction noise

[toledo-nate]

I am having a somewhat simliar problem in another building but I know it cant be air in the line because it is on the ground floor. I can actually see the radiator "shutter", but Im thinking this problem might be due to such a pressure difference on the control valve that is there. since no one in the building likes to have their heat on and this apt. is closest to the boiler room he gets to be the lucky one. Not sure on how to fix it unless i put in a bypass line or something

[drrtu]

It sounds like a zone valve, expansion pop, check valve or water hammer. Have you correlated the noise to pump operation? PB does not carry sound like metal pipe so your noise at the end BB is odd. Have you tried using a screw driver like a stethoscope? Try picking up the sound on other units BB pipe.

[propmanage]

You must have a loose hanger or something in that wall. If you have checked out these other issues, that banging may actually be a something loose banging in the wall do to pressure flow or temperature. You will never know unless you get in the wall and see for your self.

Good luck

[sigma]

An update please.

[onetime]

Depending on the way the system is piped it may be a velocity problem through the piping system as zones open and close, many systems basically deadhead if all the valves are closed, there may be a by-pass line between the pump disharge and return to relieve this problem, it may need to be opened some, they are sometimes closed by unknowing people. In our area we see many apartment bldgs. piped this way, not the best way, but cheap.

[otto]

On a side note: If you have a 40 gallon natural expansion tank with an airtrol fitting, then you shouldn't need any air vents on the boiler. Actually you should not have any air vents.