Weird consistent pipe knocking noise regardless of opening or closing ball valve

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mzhou184

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I recently moved into a high rise building condo(36 floors) and within the first night I noticed a consistent knocking noise in the wall that is more frequent during early mornings and late nights, it is very noticeable and can be heard anywhere in the entire unit, it is driving my wife and I crazy and we would wake up at 3-4am in the morning because of it. We can't go to sleep without ear plugs now.

My building has a central boiler in the top floor and sends hot water to each floor/unit, the hot waster runs through the fan coil unit in each unit zone and output hot air. It flows in the following direction: Central Boiler-->Building Zone Main pipe that goes through floors(wrapped with rubber insulation) -->flow control ball valve of my unit(it is right by the building main pipe)--> zone valve actuator -->fan coil unit. No hidden pipe is unaccounted for here.

I opened up fan coil unit cover and learned that the noise came from the hot supply valve and pipe going to the fan coil unit and I can feel the vibration in the pipe when the sound goes off . We have a four pipe system with 1 hot supply line/1 hot return line and 1 cold supply line /1 cold return line, the only pipe that vibrates when the sound goes off is the hot supply line, nothing on the other three. I asked my property manager and building engineer if my neighbors had the same complaint and apparently nothing had been reported, and if there is air in the pipes, everyone would hear it. This rules out the Building zone main pipe from the problem.

Please see the video I uploaded on Youtube documenting the sound:


I tried to troubleshoot on what might be the cause:

1. Turned off all the power in the entire unit (switched off breaker box main), noise persists
2. Manually closed the flow control ball valve of hot supply line, noise persists
3. Manually closed the flow control ball valve of all the pipes, noise persists

As mentioned before, the vibration can only be felt on the hot supply line as the sound goes off, this leads me to believe it might be the ball valve (valve that controls flow of water from building main pipe to our unit's fan coil unit) failing that's causing this noise because the noise kept going even after powering off everything and regardless of opening/closing the valve.

I hired a contractor to take a look and he checked over everything including the zone valve actuator to make sure it was opening/closing as intended and it was. He arrived the same conclusion as me: faulty ball valve because nothing else seems to be the culprit, but before deciding to change the valve I wanted to make sure this is indeed the issue because changing the valve requires draining the pipe of the entire building, that's a lot of water we are talking about and we'd have an entire building without heat for a couple hours.

Thanks for the help!
 

Twowaxhack

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I’m have zero experience with these systems.

But it sounds like a hot water pipe expanding and as it expands it makes a “ tick “

That would drive me nuts.

Good luck 👍
 

mzhou184

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Why is this your problem?

Building management should fix it.
They said if it's common element's problem, such as the main pipe, they are responsible for it, if it's anything within my unit itself I am responsible for it.
 

mzhou184

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I’m have zero experience with these systems.

But it sounds like a hot water pipe expanding and as it expands it makes a “ tick “

That would drive me nuts.

Good luck 👍
All the pipes are visible and it immediately connects to the main pipe that has a heavy rubber insulation wrapped around it throughout the run, that's why I don't think its expansion/contraction noise because the pipes are not hitting any hard surfaces.
 

Twowaxhack

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All the pipes are visible and it immediately connects to the main pipe that has a heavy rubber insulation wrapped around it throughout the run, that's why I don't think its expansion/contraction noise because the pipes are not hitting any hard surfaces.
If you say so then that’s all I have.

Good luck 👍, let us know what you eventually find.
 

Geofd

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If this fan coil provides heat for your unit and it's controlled by a thermostat is there a switch
That has a position for heat/cool/off have you shut off the thermostat,
 

JG plumbing

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It's very hard to say what this is. It doesn't sound like something a ball valve would do.

Question. When the guy came to look at it, did you tell him you think it may be the ball valve?
 

FishScreener

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The sound is very mechanical, more of a check valve opening and closing than a flow, or thremal expansion/contraction noise.
 

Amber11

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This tick tick is strange ..... have you identified the reason or not?
 

mzhou184

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It's very hard to say what this is. It doesn't sound like something a ball valve would do.

Question. When the guy came to look at it, did you tell him you think it may be the ball valve?
he thinks it might be the boiler's issue and that it needs to be power flushed
 

JG plumbing

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he thinks it might be the boiler's issue and that it needs to be power flushed
I thought you said he arrived at the same conclusion you did, a faulty ball valve?
I was asking if you steered him toward that, becuse it doesn't sound like a ball valve issue to me.
 

JG plumbing

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I don't think your problem is in the piping. I think the unit in your apartment is just being heat stressed. Things don't come from the factory exactly the same all the time, you probably can't see what's making the noise nor could you probably fix it. I'm guessing a new unit in your apartment would be the only thing I would get rid of that noise.

Instead of doing all that is there a way you can dampen the noise? Have you tried anything to dampen the noise? Rubber vibration isolators? Adding insulation? All sound is vibration, if you could find a way to deaden the vibration somehow it might be a good solution.
 

mzhou184

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I don't think your problem is in the piping. I think the unit in your apartment is just being heat stressed. Things don't come from the factory exactly the same all the time, you probably can't see what's making the noise nor could you probably fix it. I'm guessing a new unit in your apartment would be the only thing I would get rid of that noise.

Instead of doing all that is there a way you can dampen the noise? Have you tried anything to dampen the noise? Rubber vibration isolators? Adding insulation? All sound is vibration, if you could find a way to deaden the vibration somehow it might be a good solution.
Too bad I had just purchased this unit, can't really pack up and leave. What I noticed is that if there is no hot water from the boiler flowing through then there is no sound, for example when outside is over 70 degrees, but as soon as outside temperature dropped to a certain threshold and hot water flows from the boiler the noise would come back, regardless of leaving the ball valve opened and closed.

This noise wasn't there before because the property management never received complaints from prior owners, it's newly developed problem.

What type of products can dampen noise from valves/pipe? We can't just fill the entire space with insulation because we still need heating and ac to come out from it.
 
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