Continuous hammering noise

Hello,

We are hearing this continuous hammering noise from our plumbing lines. It happens through-out the day and night. Although it is very prominent during the night, may be bacuse it is quiet.

We hear a continuous hammering noise for a minute then it will be silent for a minute. Again it starts after a minute. We are not using water at all during that time. I think this is coming from our heating system lines (we have hot water boiler that circulates water thru' baseboards for heating).

Is anybody facing this problem? Any ideas/suggestions will be greatly appreciated.

Thanks
Vasan

Sounds like the heating system lines are going through flooring or studs and is touching the wood. As the pipes expand and contract they rub/move on the wood and make the sound you are hearing. It doesn't move smoothly it will jump and this is when you hear what sounds like hammering.

Just a guess, from where I am sitting.

humming

Water can slightly leak out the flush valve and cause the ballcock to barely come on and instead of hissing, there is a slight vibration.
I'd go to the toilets and listen first.

Shut off the water to the toilet(s) one at a time and see if it goes away. If it does, leave the toilets turned off overnight. My guess is that you will find the tank empty when you wake up. If so, then replace the flapper valve. You might want to replace the fill valve, too, if that is the case while you're at it. If this doesn't help, then try turning the heating system off for a couple of hours. If the pounding stops after awhile, then it is the heating system's pipes expanding/contracting. A third possibility that I can think of (I'm not a pro), is a prv (pressure relief valve) that is failing. This should give you a few things to check, then get back to us for some more ideas if neitherof these help isolate the problem.

If you have Honeywell zone valves and they are installed backwards they will make a clunking noise when there is a heat demand.

Thank you all for your reply. It seems to be coming from the Hot water supply lines from Heating system. I kind of know the pipe segment that's causing major noise, but most of the segment is hidden. Is there a way to locate it more accurately? I checked the piping and it seems tightly fixed to the ceiling. I mean pipe cannot move and bang. But I am not sure about the hidden segment.

This noise starts only when there is a water flow. I know this because when the heat is has reached the required level I don't hear any noise. When it drops, boiler starts to heat-up and after 10 seconds this noise also starts.

But the boiler starts to heat-up every 2-3 minutes and heats for about 30-40 seconds and stops. again it starts after 2-3 minutes. Is it normal?

One more thing to note is the way my expansion tank is installed in the heating system. I donot have a Exp Tank in my Hot Water system and it is not a Closed Loop. I have one Expansion Tank in Heating System that is located very close to the boiler, but on the hot water side. I have read in many posts that it should be located on the Cold water side. Is that a problem? (I had posted another message in this forum for this question: https://terrylove.com/forums/showthread.php?t=4996)

Thanks for all your help. My wife would greatly appreciate your help too. She is so upset with this house just beacuse of this problem.

Thanks
Vasan

I had a problem with my hot water boiler that was doing the same thing. It was caused by cavitation in the boiler when it was firing. A steam bubble is created when there is a hot spot in the boiler that exceeds the boiling point temperature for the pressure in the boiler. When that bubble collapses, it makes a hammering noise. It occurs only when the boiler is running. The sound is transmitted through the circulation system.

You can verify that this is the problem by looking at the pressure gauge on the boiler when it is happening. You will see the needle pulsating. You may also see the temperature gauge above 210 F.

The problem was eliminated by the following changes, all of which contributed a little to the solution.
1. Increased the pressure just a bit, well within the "green" range on the pressure gauge.
2. Decreased the maximum temperature setting on the Aqustat.
3. Changed the firing nozzle from 1.0 Gallon per hour to 0.85 gallon per hour.

The problem has not recurred since the changes.

Your pressure tank for the heating system is in the right position...it has to be within the closed system, in your case the heated side of things. If your supply system was also closed, then it would be prudent to put another one there and the preferred side is the cold side of that supply.