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Sounds like a water slide sweeping across the wall, into radiator

This concerns a Victorian home, we've lived in for decades. I've never heard the plumbing and heating system make a similar sound. 50's- to 60's furnace, 4 1/2 year old boiler, forced hot water into cast iron radiator heat. Not not a heating effected issue.

Yesterday when no water was running, it sounded like someone installed a water slide inside the wall, not in places pipes are likely situated. This sounded like separate trickling streams of water were running down from ceiling height, to mid wall height, on our 2nd floor in one wall, not at base board level, where I assume pipes would be.

The concurrent, individual trickles of water sounds, that seemed to be running down the wall from the ceiling then rapidly shifted to a sound like a water slide going whoosh mid wall range across the wall, and that then cumulated in a sound like a toilet has flushed within the wall, then one flushing inside the radiator. Then the sound, a toilet makes when it's bowl is refilling inside the radiator, then silence. There is a attic above our 2nd floor ceiling. No water or pipes at that level in the house. This sound display happened twice in an 8 hour period, and then nothing more was heard.

I'm familiar with the sounds radiators and pipes in older homes make, when radiators need bleeding. This does't sound like that. There's no knocking or sputtering, as though air were trapped within the line, or radiator.

I've never heard water sounds inside a wall when that occurred, doubt there are pipes in the the middle of the wall. There is a chimney smack in the middle of the wall in question, that the whooshing seems to go across, in it's path to the radiator.

When it happened the 2nd time, I went over to listen and given the loudness of the sounds, expected to find a pool of water on the floor. It was that pronounced of a sound. The only time I've heard anything like it, in my life time, was when a below sink seal rotted out, and started to shoot water hot water like a garden hose, That was in another home. There are no signs of leaking water, anywhere in the home. This sounded like it was raining inside the wall.

Does this just sound like the radiators just need to be bled, or that a pipe is getting ready to rot out in the wall? We have not bled the radiators in years. If there were leaks in the piping running into that radiator, we would see water, correct? Should we call a plumber in to look, or simply bleed all the radiators, and go from there, any thoughts?


  • Larry Weingarten
    Larry Weingarten Member Posts: 2,546
    Hello, It's a strange one! I think I'd want to have a look at the wall and surrounding areas with an Infra-red camera and see what it can show. Clearly, more info is needed to know how to proceed. I'm pretty sure people on this site will want to see pictures of the boiler and near boiler piping. Also, it would be good to know if the boiler was or had been recently running when you heard the sounds. ;)

    Yours, Larry
    JUGHNE Member Posts: 9,760
    Do you have thermostatic rad valves on the 2nd floor?
  • Intplm.
    Intplm. Member Posts: 1,376
    Just for starters, I would bleed , purge the radiators. I would do this just to make sure the radiators have no air in the system. It's the simplest thing to do. If that eliminates the noise, than you can look for the cause of the air getting into the system and making said noise.

    From your description, it seems that it only happens when the upstairs zone calls for heat. I'm guessing due to its age that you have over sized piping serving the feed and return to the upstairs? This might be why the volume of the noise is much louder than a common, say 3/4" feed and return would make?

    Purge the rads first than go from there.
  • Jamie Hall
    Jamie Hall Member Posts: 18,931
    Um... yeah, purge. But... is there any ice or snow on the roof in the vicinity of the chimney? Backed up somehow? Which might have melted?
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England