Troubleshooting Water Hammer

John R

Hi Guys,

Very novice guy trying to determine what's causing the water hammer like sounds from my hot water radiator system.

I've had banging noises off and on, so I logged them the last couple of nights:

Boiler turns on, then 30 seconds later, I hear a water-hammer like sound in the ceiling in my basement, right where the mains must rise to the upper floors and to a free-standing radiator right above.

Water temp. reads 80 F and PSI reads about 15 PSI when this happens.

Happened twice and both gauges were at about the same level.

Is 80 F water hot enough to cause the banging when it meets the cold(er) water in the radiator (if that is why it's happening)?

Haven't cleaned the boiler since we moved in (2003). Any chance this is the problem? Could it be the radiator up above the mains, and not the main itself that is making the terrible noise? It's hard to tell because the pipes are above the ceiling and the hammer-noise occurs right around the radiator's location on the floor above.

Also, when I've removed water from the system via the pressure overflow valve, I take the PSI to around 12. Then it somehow moves back up to around 15 when cold/off, then to 20 when running at 180 F. Is this anyway related to my hammer problem? Maybe air is getting in to system?

Could the valve that brings in fresh water be letting water in given that it is set (I think) to open only when pressure drops below 12?

Sorry for the wordy (not worldy!) post.

Any help would be mondo appreciated.

Thanks,
John

martin

Banging noise

way to many variables to come up with anything concrete. Need more info. Its hot water, forced or gravity.maybe a pic or 2

John R

Pics of Boiler Components

Sorry, I should have included pictures.

I think that it's forced, as it has a circulator pump (see attached picture).

The rad pictures are of the radiator at the point where I hear the banging noise, after the pipes go in to the chase and down the hallway into my office and then up(see pic of main going in to the chase - the one on the right is outgoing from boiler and left is return).

I was thinking of closing the valve for the radiator to see if that made a difference, but haven't yet done so.

If you need any more pictures, please let me know, or want me to try something with the boiler.

Thanks,
John

gary disney

relak

pipes do not bang when cold not unless the boiler is sitting hot and then fires up.chec that the boiler is shutting of when a cycle is finished r the radiators all heating up,pressure should be 5psi per floor . the boiler should not leak on a cycle unless the pressure goes ove 30 psi.do not believe what a guage on a boiler reads. ur system is full of air and hi water tempatures and needs a expansion tank replacement and a expert.do u even know if u have a steam system or a forced hot water system.

John R

The boiler is definitely shutting off when a cycle finishes; I only hear the circulator pump going after that. The boiler doesn't seem to leak but sometimes when I stick my finger up the pipe that leads out of the pressure relief valve, there is some cold water on the sides (and maybe a tiny bit on the floor below). The expansion tank is never hot on the bottom (which would indicate a broken diaphragm), but I can remove and check for water and pressure setting (can't recall what it should be set for).
I believe it is forced hot water, but I don't know how to tell other than my pressure gauge.
Thanks,
John

gary disney

> Sorry, I should have included pictures.

>

> I

> think that it's forced, as it has a circulator

> pump (see attached picture).

>

> The rad pictures

> are of the radiator at the point where I hear the

> banging noise, after the pipes go in to the chase

> and down the hallway into my office and then

> up(see pic of main going in to the chase - the

> one on the right is outgoing from boiler and left

> is return).

>

> I was thinking of closing the

> valve for the radiator to see if that made a

> difference, but haven't yet done so.

>

> If you

> need any more pictures, please let me know, or

> want me to try something with the

> boiler.

>

> Thanks, John



> Sorry, I should have included pictures.

>

> I

> think that it's forced, as it has a circulator

> pump (see attached picture).

>

> The rad pictures

> are of the radiator at the point where I hear the

> banging noise, after the pipes go in to the chase

> and down the hallway into my office and then

> up(see pic of main going in to the chase - the

> one on the right is outgoing from boiler and left

> is return).

>

> I was thinking of closing the

> valve for the radiator to see if that made a

> difference, but haven't yet done so.

>

> If you

> need any more pictures, please let me know, or

> want me to try something with the

> boiler.

>

> Thanks, John



try this. check boiler is cold when not on a cycle. turn up thermastat watch boiler dos it get hot fast feel the flow line, if pump is working water should circulate from the boiler slowly,if boiler is getting hot fast u have little or no flow from the pump, gravity circulation is possible.remember all is not what it seems.if boiler is over heating it can also leak water from the relief valve. ur boiler looks like a ao smith hi out-put boiler for hot water heating, which needs a hi flow rate,

gary disney

well no leak no problem in that department.check dos the boiler short cycle o n tempature,

John R

short cycling

I recently installed a honeywell digital therm and don't have any short cycling. Actually, I think I remember getting short cycling once about 4 days ago, but that was it. Sometimes it only stays on for 15-20 minutes though (my guess), but that is usually when the temperature falls down to my preset 'on' level (e.g. temp falls from 64 to 63, and 63 is the "turn on" temperature). But if the room is 64 and I set therm to say 68, boiler stays on for a long time.

Does it matter that there is some water on the inside of the outlet pipe for the pressure relief valve (but not any noticeable water on the floor, if any)?

John R

Boiler and Circulator

Yes, boiler is AO Smith. Not sure what hi-flow rate means though. It is not used for hot water heating though, as in hot water for cooking and showering. Have a separate hot water tank for that. I'll check flow line in the morning as I don't want pipes to bang this late at night.

Also, how can I tell if boiler is get hot fast - by reading the temp gauge you mean? Can you explain the part about pump working and water circulating slowly from boiler. Not sure how to tell if water is circulating slowly from the boiler. I can feel the main pipes, but they are thick so I'm not sure how fast they should feel hot when boiler and pump are operating correctly.

Thanks,
John