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Old 09-11-2021, 08:23 AM   #1
JBR160
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Water Hammer

Trying to figure out my water hammer issue that started this season. I replaced the water pump last year with a Shurflo 4008-101-E65 and everything ran great all last season.

This season the water hammer started on our first trip. I have checked for leaks thru out the camper and could not find anything. I had a small drip leak at the water tank fill. Tightened the hose clamps and that took care of that problem. It does not hammer when I hook up to city water at all, only when on the pump. Also, the pump does not run constantly and this only happens when I turn and of the faucets or flush the toilet. Tightened all the pump fittings and even pulled the pump to check the diaphragm and could not see any splits or cracks.

Thought I would check with the experts before I either go and purchase a new pump or drop it off at the RV mechanic. Really do not want to pay the $150 per hour to tell me something I could have done myself!

Any help would be appreciated!
Thanks
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Old 09-11-2021, 09:19 AM   #2
wiredgeorge
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Quote:
Originally Posted by JBR160 View Post
Trying to figure out my water hammer issue that started this season. I replaced the water pump last year with a Shurflo 4008-101-E65 and everything ran great all last season.

This season the water hammer started on our first trip. I have checked for leaks thru out the camper and could not find anything. I had a small drip leak at the water tank fill. Tightened the hose clamps and that took care of that problem. It does not hammer when I hook up to city water at all, only when on the pump. Also, the pump does not run constantly and this only happens when I turn and of the faucets or flush the toilet. Tightened all the pump fittings and even pulled the pump to check the diaphragm and could not see any splits or cracks.

Thought I would check with the experts before I either go and purchase a new pump or drop it off at the RV mechanic. Really do not want to pay the $150 per hour to tell me something I could have done myself!

Any help would be appreciated!
Thanks

John, Start by explaining what you mean by "water hammer". Is this only when you are using the fresh water tank and pump or with the city water connected?
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Old 09-11-2021, 09:31 AM   #3
JBR160
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Originally Posted by wiredgeorge View Post
John, Start by explaining what you mean by "water hammer". Is this only when you are using the fresh water tank and pump or with the city water connected?
Only when I am using the fresh water tank an pump. Does not happen when connected to city water. The hammering/shaking sound starts as soon as you turn a faucet on and continues after the faucet is turn off as the pump is still running for a second.
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Old 09-11-2021, 09:44 AM   #4
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Check your water heater bypass valve to make sure it is not partly open. Also check your toilet vacuum breaker, located just behind the seat hinge.

I'm not sure how to "fix" your problem, but I'd think installing an accumulator tank would "mask" the problem by allowing an expansion capacity to "soften the hammering".

Shur-flo markets an expansion tank specifically for use with their RV water pumps.

https://www.amazon.com/SHURFLO-182-2...46988215&psc=1
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Old 09-11-2021, 09:48 AM   #5
Diver
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your waterline is banging against a wall .. floor or cabinet
try to find a loose area that it moves i pit pipe insulation around mine and secured a few areas
mine was hittin shower enclosure ... thankfully i could access it under sink enclosure
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Old 09-11-2021, 05:03 PM   #6
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My Montana has water hammer occasionally and I cannot figure out why, For the most part, the water pump runs and all is relatively quiet. But sometimes, right after filling the fresh water tank, for about the first 10 gallons used, the pump will all of a sudden go into this "hammer" mode. Then just go quiet again.

Sometimes, after traveling and after getting set up for camp, the first few gallons will all of a sudden start the "hammer" sound. Then, it just quits. It doesn't make any sense because when this happens, the camper is usually sitting stationary for a while. Like I said, happens mostly right after filling the fresh water tank. Then sometimes, not at all.

I do know the actual water pump runs very, very quiet. I replaced one in my previous camper and they barely make a purr sound. The vibration from the pump amplifies through the pipes like a megaphone and can sound like the camper is going to explode from the sound. In my previous campers, I've tried all kinds of things to quiet the noise and very little worked. Mainly, because the vibration occurs where pipes pass through the walls and floors where access is impossible.

With my current camper, the pump is up front behind the wall in the fifth wheel over hang pass-through. But the hammering sound comes from under the shower pan, which is near the rear of the trailer. Also, the fresh water tank is in the rear also.

When filling the fresh water tank, it's done from the front, goes to a tank in the rear. Water pump is up front, so it pumps water from the tank in the rear, back to the front. From the front, it passes through the water pump and then to the back again for the shower, toilet, washing machine, and bathroom sink. That's a lot of pipe to vibrate.

Really, there is nothing getting damaged when you hear the noise, nothing is broken, nothing is wrong. It's just annoying noise. We just live with it. It's not worth the effort to tear (this) camper apart, like I did my last one to do a fix that never fixed anything.
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Old 09-12-2021, 04:29 AM   #7
JBR160
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Quote:
Originally Posted by JRTJH View Post
Check your water heater bypass valve to make sure it is not partly open. Also check your toilet vacuum breaker, located just behind the seat hinge.

I'm not sure how to "fix" your problem, but I'd think installing an accumulator tank would "mask" the problem by allowing an expansion capacity to "soften the hammering".

Shur-flo markets an expansion tank specifically for use with their RV water pumps.

https://www.amazon.com/SHURFLO-182-2...46988215&psc=1
Thank you for the info. I will double check the water heater bypass and the toilet today. The Shurflo accumulator is reasonably priced so I might order one of those as well.
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Old 09-12-2021, 04:34 AM   #8
JBR160
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Quote:
Originally Posted by dutchmensport View Post
My Montana has water hammer occasionally and I cannot figure out why, For the most part, the water pump runs and all is relatively quiet. But sometimes, right after filling the fresh water tank, for about the first 10 gallons used, the pump will all of a sudden go into this "hammer" mode. Then just go quiet again.

Sometimes, after traveling and after getting set up for camp, the first few gallons will all of a sudden start the "hammer" sound. Then, it just quits. It doesn't make any sense because when this happens, the camper is usually sitting stationary for a while. Like I said, happens mostly right after filling the fresh water tank. Then sometimes, not at all.

I do know the actual water pump runs very, very quiet. I replaced one in my previous camper and they barely make a purr sound. The vibration from the pump amplifies through the pipes like a megaphone and can sound like the camper is going to explode from the sound. In my previous campers, I've tried all kinds of things to quiet the noise and very little worked. Mainly, because the vibration occurs where pipes pass through the walls and floors where access is impossible.

With my current camper, the pump is up front behind the wall in the fifth wheel over hang pass-through. But the hammering sound comes from under the shower pan, which is near the rear of the trailer. Also, the fresh water tank is in the rear also.

When filling the fresh water tank, it's done from the front, goes to a tank in the rear. Water pump is up front, so it pumps water from the tank in the rear, back to the front. From the front, it passes through the water pump and then to the back again for the shower, toilet, washing machine, and bathroom sink. That's a lot of pipe to vibrate.

Really, there is nothing getting damaged when you hear the noise, nothing is broken, nothing is wrong. It's just annoying noise. We just live with it. It's not worth the effort to tear (this) camper apart, like I did my last one to do a fix that never fixed anything.
I wish mine would only do it for a short period. It seems it does not matter what the level of the tank is at. If you just run the faucet to wash your hands or just flush the toilet, it is not too bad. If you want to take a shower though, it gets really annoying!
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Old 09-12-2021, 06:11 AM   #9
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My OEM Shurflo water pump has been doing what you describe since 2014... Its not an issue ... IMO
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Old 09-12-2021, 07:21 AM   #10
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If "water hamering" is only present while using the FW pump then the FW pump is obviously the source. The pump will naturally "pulse" as the pressure increases/decreases and thatcan cause the water line to vibrate. If the vibration occurs at the pump a water pump "silencing kit" may help or padding or rerouting the water lines may help.

In my limited experience I've found the accumulator tank the best option. Inside that tank is a bladder that you inflate with air. As water cannot be compressed and air can, it acts as a shock absorber to dampen the fluctuations and deliver an even flow. The other advantage, depending on the size of the accumulator, is in reducing the number of times that the pump cycles on and off. Drawing a glass of water, a quick toilet flush, or rinsing out a tooth brush may not require the pump to run.
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Old 09-12-2021, 11:52 AM   #11
JBR160
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Originally Posted by flybouy View Post
If "water hamering" is only present while using the FW pump then the FW pump is obviously the source. The pump will naturally "pulse" as the pressure increases/decreases and thatcan cause the water line to vibrate. If the vibration occurs at the pump a water pump "silencing kit" may help or padding or rerouting the water lines may help.

In my limited experience I've found the accumulator tank the best option. Inside that tank is a bladder that you inflate with air. As water cannot be compressed and air can, it acts as a shock absorber to dampen the fluctuations and deliver an even flow. The other advantage, depending on the size of the accumulator, is in reducing the number of times that the pump cycles on and off. Drawing a glass of water, a quick toilet flush, or rinsing out a tooth brush may not require the pump to run.
I appreciate everyone's suggestions. Checked out the water heater bypass valve and the toilet this morning and everything is normal there. I will be ordering an accumulator and giving that a try. I will post my findings once I get it installed.

The only thing that makes me keep shaking my head, is that this did not happen last year when I installed the new pump! The whole system was very quite. Oh well, I guess you know what happens sometimes!

Thanks again!
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Old 09-12-2021, 12:42 PM   #12
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I appreciate everyone's suggestions. Checked out the water heater bypass valve and the toilet this morning and everything is normal there. I will be ordering an accumulator and giving that a try. I will post my findings once I get it installed.

The only thing that makes me keep shaking my head, is that this did not happen last year when I installed the new pump! The whole system was very quite. Oh well, I guess you know what happens sometimes!

Thanks again!
I'm just guessing but perhaps a water line shifted so it now hits a wall or the floor where it "just missed" it previously.
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Old 09-13-2021, 06:57 AM   #13
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When it hammers does the water flow pulse as well? I have only used my FW tank a couple times but it seems like mine does this as well (hammers) but the water pulses somewhat too.

The way mine is set up is very strange. First, no gravity fill so you have to have pressure to get from the back wall of the trailer where the connection is, up to near the kitchen where the tank is located. Then the water has to flow all the way back from the tank to where the water pump is located, which is also near the back wall of the trailer.

I just figure that there is a kink in the run from the FW tank back to the pump, causing the hammer, but still allowing some flow. But maybe a kink like that wouldn't cause enough to make it hammer and pulse?
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Old 09-13-2021, 10:08 AM   #14
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When it hammers does the water flow pulse as well? I have only used my FW tank a couple times but it seems like mine does this as well (hammers) but the water pulses somewhat too.

The way mine is set up is very strange. First, no gravity fill so you have to have pressure to get from the back wall of the trailer where the connection is, up to near the kitchen where the tank is located. Then the water has to flow all the way back from the tank to where the water pump is located, which is also near the back wall of the trailer.

I just figure that there is a kink in the run from the FW tank back to the pump, causing the hammer, but still allowing some flow. But maybe a kink like that wouldn't cause enough to make it hammer and pulse?
Yes, the water pulses as well. The way my rig is set up in that the water pump is located under the kitchen sink just about mid cabin. The water tank is directly below there, maybe just a little forward. There is not a very long way the water needs to go from the tank to the pump. Just a few feet.
The kitchen faucet and bath tub/shower seems to pulse the most. The vanity sink and toilet do it the least. Those two are plumbed in between the other two. Not sure if that means anything or not.
Going to try and find out what pipes are making the most noise and see if I can insulate them be fore I put the accumulator in.
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Old 09-13-2021, 07:06 PM   #15
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Before you buy an accumulator, you can test to see if it will help by draining your water heater, the refill it from the fresh water tank. Don’t open any hot water faucets, you want the HWT to have extra air it. Then run cold water from the faucets that have had the most pulsing. The air on top of the HWT will dampen the pulsing just like an accumulator would. If that works to reduce the noise, bleed the excess air off the HWT through one of the hot water faucets to see if the noise comes back. RV water heaters are supposed to have air on top to allow for expansion but that air also dampens vibrations that travel through the water in the piping. If you somehow lost that air, you would experience more noise from your water piping
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Old 09-14-2021, 06:13 AM   #16
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Before you buy an accumulator, you can test to see if it will help by draining your water heater, the refill it from the fresh water tank. Don’t open any hot water faucets, you want the HWT to have extra air it. Then run cold water from the faucets that have had the most pulsing. The air on top of the HWT will dampen the pulsing just like an accumulator would. If that works to reduce the noise, bleed the excess air off the HWT through one of the hot water faucets to see if the noise comes back. RV water heaters are supposed to have air on top to allow for expansion but that air also dampens vibrations that travel through the water in the piping. If you somehow lost that air, you would experience more noise from your water piping
Thanks for the suggestion. I will give that a try!
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Old 09-16-2021, 02:27 PM   #17
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As mentioned about expansion tank, this is what I also put in.

Before you spend money… open up the area to get access to pump and water lines.
Then have someone turn on pump and then water.

Listen for the knocking that you call hammering.
Anywhere a water line to/from the pump touches something or each other will vibrate and knock. Move the lines gently and listen where it is.

This is a good place to use hvac split foam tubing to cover lines. I split some pool noodles and insulated the lines from each other or where they touched a wall.

Since RV manf use pex tubing to tge pump or near it, the pump vibration is very noticeable.

I disconnected lines on both sides of the pump and got flexible plastic water lines (like some houses). Match the ends to your water line and pump fittings so the screw right on. The trick is to put a large loop in the lines do get lines about 24” long.
The loop and soft waterline nylon/plastic absorbs alot of vibration.

Be certain you isolated your new pump from directly mounting on a wall or floor. You need a rubber isolation pad.

So I have rubber isolation pad, expansion valve, longer flexible water lines and used split foam pool noodle.
RV water pumps will still make some noise.
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Old 09-16-2021, 02:31 PM   #18
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They make "pump silencer" water line kits. Here's one .. https://www.amazon.com/RecPro-Water-.../dp/B0861CHLBR
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Old 09-19-2021, 06:29 PM   #19
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[QUOTE=JRTJH;468037]Check your water heater bypass valve to make sure it is not partly open. Also check your toilet vacuum breaker, located just behind the seat hinge.

I'm not sure how to "fix" your problem, but I'd think installing an accumulator tank would "mask" the problem by allowing an expansion capacity to "soften the hammering".

Shur-flo markets an expansion tank specifically for use with their RV water pumps.

https://www.amazon.com/SHURFLO-182-2...46988215&psc=1[/QUOTE
Installed one of those]

Installed one. Worked well, but fulltime & 35k miles in18 more things change.
About 1/2 the moves , no hammering. The others may hammer immediately or wait days to start.
IMHO, it's not worth chasing any more.
We've Installed pipe foam, pool noodles Etc.
Only thing left is drop the base & put expanding foam @ every near to anything pipe.
Good luck.
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