Water Hammer

Hello
Our 44ft Island Gypsy has multiple water tanks that we use daily for our water with a pump and a small Accumulator/Pressure tank. The system ran dry a couple weeks ago and since then we have had a racket in the plumbing. Sounds like water hammer to me. It only starts making noise once you shut off the water and the pump is building pressure in the tank.
Ive tried bleeding the faucets but no dice.
I opened up every water faucet and the showers then shut off the pump. I let the water run out then turned the pump back on. I then tried shutting off the faucets in order from closest to pump to furthest and vice versa . Still making noise. It's hard to tell which water fixture is closest to the pump because its located in the engine room right under the Galley sink which is separated by a wall from the Aft Master head w shower & Sink.
The sound moves around but tends to stay aft closer to the pump/tank.
Getting frustrated with it.
Would installing a Water Arrestor (sp?) help?
Any ideas?

Adam

Have you measured the pressure in your accumulator tank? It typically should be a pound or two below the cut-in pressure for your pump. Speaking of which , what is that set at? What kind of pump is it?

Sounds like the accumulator tank has failed.

When the FW pump shuts off , switch it off , and open a faucet to see how much water is in the accumulator , if any.

As mentioned, with all the pressure out of the system, check the accumulator tank pressure. Then turn on the pump. Close all the cold water faucets first. Then turn the pump off and let the pressure reach zero. Then turn it back on and wait a few seconds and close the hot water faucets. Some times getting as much air out of the water heater as possible, can be tricky.

Ted

I'll try to get in there this PM to get more info. I think it is a Sureflow pump. It seems like the bladder on the tank is ok because I do get water for 30 secs or so with good pressure without the pump on.

A

Well, another hour spent turning water on/ off w no results...yay!
Here is a little more info..
The tank at rest w no water is 20 PSI.
With water it is right around 60 PSI.
All my faucets except one do not have seperate Cold/Hot handles. They have a single handle with the mixing valve where you turn right for hot and left for cold. I tried the best I could to flush the cold then the hot but there is no way to do it 100%.
I get good flow w pump off for about 20 seconds.
Not sure where to go from here. Seems like there is air in the system and it moves around depending on which fixture I'm using but I can't seem to flush it out.

Fyi
The system tends to cycle with no water being used about once an hour. It seems to be mostly in the evening but it could just be me noticing it then. The previous owner said it has always done that and if the cycling gets to be too frequent then the tank may be low on PSI/Air? To me this means water is getting out somewhere and I've checked for leaking faucets but nothing.

A

"The tank at rest w no water is 20 PSI."


It should be a couple of pounds less than the cut ON pressure.

If it cycles there is a slow leak somewhere north of the pump. Fix that first.

Do you have an ice maker in the fw circuit? If so, it could be the cause of the random pump cycling.

Bill

Im guessing the pump has a built in pressure switch?

Best way to test cut in/off pressure?

Bildge is dry. Not sure where water would be going but it definitely cycles.

Anyone hear of using a water hammer arrestor like would be used in a house?

I have not tried flushing the heads as part of my bleeding the system. Not sure if the plumbing running to the 2 heads could be holding air.

A

Oh..and No Ice maker aboard

It’s possible to loose pressure back through the non return valve at the pump. This could explain the pump cycling with no use and no leaks but not the air in the system. Some times it can be tricky to get the air out as obviously it likes to try to stay a the highest point. If you have any obvious high points (that you suspect maybe trapping air) it is sometimes helpful to crack a fitting at this high point with pressure in the system to expel the air (and get a free shower).

Any air in the system would tend to cure water hammer , air is compressible liquid is not.

TrawlerTribe said:

Im guessing the pump has a built in pressure switch?

Best way to test cut in/off pressure?

Bildge is dry. Not sure where water would be going but it definitely cycles.

Anyone hear of using a water hammer arrestor like would be used in a house?

I have not tried flushing the heads as part of my bleeding the system. Not sure if the plumbing running to the 2 heads could be holding air.

A

Click to expand...

Find the leak

FF said:

Any air in the system would tend to cure water hammer , air is compressible liquid is not.

Click to expand...

BeeJay said:

It’s possible to loose pressure back through the non return valve at the pump. This could explain the pump cycling with no use and no leaks but not the air in the system. Some times it can be tricky to get the air out as obviously it likes to try to stay a the highest point. If you have any obvious high points (that you suspect maybe trapping air) it is sometimes helpful to crack a fitting at this high point with pressure in the system to expel the air (and get a free shower).

Click to expand...

I thought entrapped Air was the cause of water hammer ....not the cure.

Beejay-
Non return valve?
Are you saying I could be losing primed water back into my water tanks (source water) and that would cause the cycling but not show a leak or allow air to enter the system?
Would a check valve help?

TrawlerTribe said:

I thought entrapped Air was the cause of water hammer ....not the cure.

Beejay-
Non return valve?
Are you saying I could be losing primed water back into my water tanks (source water) and that would cause the cycling but not show a leak or allow air to enter the system?
Would a check valve help?

Click to expand...

Yes, it can sometimes be a problem. You can check if it is happening. Once the system is primed with all the faucets etc. closed, remove the power from the pump. Then remove and plug the inlet hose feeding the pump. (Hopefully you have a valve in this line). You say that you get a volume of water out of the faucets when the pump off. If you have a non return valve issue this water will leak back out of the pump inlet (over the time it usually takes for the pump to cycle). If this is the case then, yes, another check valve should make a difference. But it would be best to investigate what’s up with the valve in the pump 1st.

I'm still listening to lots of noise!
The water hammer noise seems to move around the Aft water fixtures but stays mainly by the Master shower and Galley sink which are in close proximity. It seemed louder than normal a week ago so I went in the engine room with the water running and the Hot water heater is making a very loud pipe banging noise when you close the faucet and the pump is trying to pressurize the expansion tank. I shut off the valve feeding the HWH and the noise stopped. I turned off the power to the HWH and left the feed valve closed and the water hammer noises from the Galley and Master shower were barely audible but after an hour or so the noise came back. I turned the HWH back on and it is still really loud too. [emoji36]
I called Raritan about the water heater but they had no ideas. He said people install water Hammer Arestors. I tried opening the Pressure relief valve on the HWH into the bildge and the noise goes away until you close the pressure relief valve. Then it returns.

I also noticed I have a trickle of water coming into the bildge from the stern somewhere. Seems like freshwater. I need to inspect all my tanks I guess?

Hoping to fix this before my pipes burst.....

TrawlerTribe said:

I'm still listening to lots of noise!
The water hammer noise seems to move around the Aft water fixtures but stays mainly by the Master shower and Galley sink which are in close proximity. It seemed louder than normal a week ago so I went in the engine room with the water running and the Hot water heater is making a very loud pipe banging noise when you close the faucet and the pump is trying to pressurize the expansion tank. I shut off the valve feeding the HWH and the noise stopped. I turned off the power to the HWH and left the feed valve closed and the water hammer noises from the Galley and Master shower were barely audible but after an hour or so the noise came back. I turned the HWH back on and it is still really loud too. [emoji36]
I called Raritan about the water heater but they had no ideas. He said people install water Hammer Arestors. I tried opening the Pressure relief valve on the HWH into the bildge and the noise goes away until you close the pressure relief valve. Then it returns.

I also noticed I have a trickle of water coming into the bildge from the stern somewhere. Seems like freshwater. I need to inspect all my tanks I guess?

Hoping to fix this before my pipes burst.....

Click to expand...

When you open the pressure valve you are reliving the pressure and the noise goes away. This sounds like air trapped in the top of the water heater tank or it's getting to much pressure.


I don't think you'll have a pipe rupture unless the plumbing is shoddy.


Is the piping, or tubing mounted solidly? It shouldn't be mounted in a way to limit expansion and contraction with temp changes. This can cause noise but it usually only happens with metal plumbing such as copper or galvanized pipe.

Ben2go..
I think you are onto something..
It seems like air is trapped in the HWH. Any ideas on how to remove? Not sure how I go about draining the HWH. It's all Copper pipe.

I doubt it is due to air in the hot water tank. The biggest problem I see from air in the hotwater tank is the danger of overheating the electric elements if they are ever exposed. Actually air in the tank would act similar to how an accumulator tank works. i.e. When the water pressure goes up the air compresses when reduces the "hammer" effect.

Assuming what you are hearing is a pulse of noise when the water pressure rapidly expands due to the pump coming on (note: many pumps put out pulses of water rather then a continuous flow), or a sudden shut off of a faucet then my guess is that either your accumulator has lost its air or one of your copper pipes have come loose and it is "jumping around" when the pressure changes.

I'm in agreement with FF. Air in the system will not cause water hammering. It often cures it since the air is compressible and stops the shock load on the pipe.

Water hammering can be caused by loose pipework, or water pressure set too high. It could also be that your accumulator pressure is set too high.

I'm thinking now that the issue I am having is technically not water hammer. Water hammer is typically a quick thud or a few but not prolonged noise. What I have going on is prolonged. I think this is Air in the pipes. Could the heat exchanger in the HWH vibrate due to air in the tank?
Any advice on getting air out of the HWH?

A

Is there a way to post video?

You probably have a swing check in the cold inlet to the water heater. You're hearing it slam shut as the pressure wave from shutting off the faucet finds its way to the check. If you have an accumulator tank, make sure it has a charge. Check it with the water shut off, drain the pressure off. Should be a couple psi lower than the cut-in pressure of the pump. It probably would help reduce the hammer if the the cold supply to the water heater is piped via a side outlet of a tee. The closer the tank is located to the check, the better the accumulator will absorb the shock and prevent the check from slamming. If you can duplicate the noise, listen at the check with a stethoscope or screwdriver to confirm the source.

All this going on about air in the system overlooks the fact that for air to be in the system, it has to be put there. It doesn't magically appear out of the blue. So the likelihood of air causing the problem is very slim. The water hammer, although intimidating, will not cause the piping to rupture, leak or otherwise fail. It's just an annoyance. If the accumulator isn't the issue, you could add a small hammertrol in the piping, it's just a small air bladder device like the accumulator tank. It's used in domestic applications where a fast-acting valve like a washing machine solenoid is causing water hammer. Very effective. Placement is most effective on the end of a long run of pipe.

FF said:

"The tank at rest w no water is 20 PSI."


It should be a couple of pounds less than the cut ON pressure.

Click to expand...

The pressure pump cuts in at 25PSI & cuts out at 40PSI
at rest 20 sounds low, should be closer to 40?

Soo-Valley said:

The pressure pump cuts in at 25PSI & cuts out at 40PSI
at rest 20 sounds low, should be closer to 40?

Click to expand...

What should be closer to 40?



Typical pump settings are on at 20, off at 40. Your settings are OK. If that's not providing what you believe is adequate flow, then there are likely some restriction issues that higher pressure may mask, but won't solve. You could leave the cut-in at 25, then the accumulator should be set at about 2 psi less, 23 psi. static (pump off, pressure bled off). If you get the tank pressure too close to the cut-in setting, the flow may stop as the pump starts, that'll compound your noise problem.

TrawlerTribe said:

I'm thinking now that the issue I am having is technically not water hammer. Water hammer is typically a quick thud or a few but not prolonged noise. What I have going on is prolonged. I think this is Air in the pipes. Could the heat exchanger in the HWH vibrate due to air in the tank?
Any advice on getting air out of the HWH?

A

Click to expand...

You may have a check valve that's chattering. A spring check can very easily create some odd noises if it's rattling around in the flow, a swing check can also make noise. Water piping can transmit that noise so that it appears to move around the system. Check around the pump and the water heater with a mechanic's stethoscope or long screwdriver to zero in on the source of the noise. If you have air in the pipes, it will come out spitting at the faucet. Is that happening? If not, no air.


The pump probably has an integral check valve. If it's not seating tight, it can cause the pump to cycle as the pressure bleeds back past the check into the water tank. There's no visual clue to that action.

No, it's unlikely that the heat exchanger in the water heater would vibrate for any reason. Air in the tank? If you've drained and refilled the water heater, there may be some air trapped, it will vent naturally. Otherwise, there's no source for air. It's highly unlikely that your problem is related to air.

Soo-Valley said:

The pressure pump cuts in at 25PSI & cuts out at 40PSI
at rest 20 sounds low, should be closer to 40?

Click to expand...

should have said closer to 40 on shutoff. OP says it is 60 going past rating.

Update....
Finally figured out our "water hammer".
It was a pipe/tube inside our Raritan water heater vibrating due to our fresh water pump. The pump was only a little over a year old and was functioning but vibrating a lot. It would take a long time to fill our pressure tank. I temporarily connected dock water via a hose connected to our outdoor shower as a feed since our boat doesnt have an actual dock water connection. Only water tanks and the pump. This was a good temp fix to avoid all the noise untiI i could figure it out.
I bought the same pump new to replace the existing to see if it would help and low and behold....no more loud annoying noise.
New pump Installed
No noise and way quieter. I didn't realize how loud the other pump was.
Fills the pressure tank way quicker.
I will keep the old pump as a back up.
Now onto the next project....

Add some hose length by adding a loop. Short hoses can telegraph the pump vibration to what ever the pump is connected to.

Also, try a different mount for the pump. I improvised these and it’s cut the noise down significantly.