Hotwater boiler ( banging noise extremely loud and vibration)


Hello Dominick,

i have a few questions regarding my home boiler. I have recently changed out few set of heating pipes in my house. When i uncrew the union from the pipe lost of water running out. after changing out the pipe boiler water gage always full. when heat kicked on, at first extreme bang noise which vibrated the entire house.. scary…

I am trying to understand how the hotwater boiler heating system works. I notice the water are not stored int he pipe and not being return to the boiler, should they be water in the pipe or just the steam from the boiler going thru the pipe to the radiators?

after temp cold down then water to thru return pipe back to the boiler?

My main concern right now is the boiler always full but yet asking for water when needed… and the banging of the noise. please help . i would really appreciated it… please educate me on this.. i really appreciated it…


Thank you



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, Romie Rome 3 years 5 Answers 710 views 0

Answers ( 5 )

  1. Yes you need it. As the water heats up it expands. The expanded water needs to go somewhere. The tank has a bladder in it, one side water the other side air.

    You must have pressure in the system. If you do not, make sure the fresh water supply is open and left open all the time.

  2. if you meant the pressure gauge at the top of the boiler, that is working fine.  but i am not sure what psi it stated… I will check and get back to you.

    can you explain to me what does the water expansion  tank does and do i need that on my boiler??


  3. What does the pressure gauge dead? it should be 15-19psi

  4. Hello Dominick, ty for your fast response.

    I have bleed the system several times. same issues….

    when i changed the piece pipe and the excess water came out of the pipe, i noticed the boiler water gage went down a little.

    It seem like the excess water are not returning to the boiler, i noticed the pipe are not balance to return the water.  seem like all the excess water are being stored in the pipe causing it bang extreme loud when the boiler turn on.

    would that be an issues?  please help.. ty..


  5. You’ll need to bleed the system out.. Watch video

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