Reduce "Water Hammer" in a Permeate Pump Brine-Out Line

[Jimbus]

Hi Plumbing Experts,
I'm brand new to this forum and I know nothing about plumbing. I installed a 7 stage RO system under my sink early last year and never really got the system to meet my expectations. The last part of the system I'm trying to fix is the operating volume. Please if you know how to reduce the noise of an under-sink RO system, help me out...

Description of Problem: very loud sound & vibration (like a "water hammer?") when the Brine-Out Line begins draining from the Permeate Pump. This is not a new occurrence, it has happened for the entire lifetime of the system. I'm hoping to find a way to reduce the volume of the sound.

It's a very simple system, as you can see in the attached diagram, the Permeate Pump is an ERP 500 and I've got a 35 GPD membrane. The filters and everything are in good condition, they're relatively new. The hoses/lines are all ez-fit and there are no leaks. I have bled the system multiple times to ensure there is no air trapped inside. I recently input a flow regulator on the inlet line to the system, reducing the pressure to 60 PSI. This was a good decision, because it helped remove tiny bubbles from faucet water. It helped reduce the "water hammer" before the tank gets fully pressurized; but when the tank is near full, jeez the permeate pump is noisy.

So far, I've considered adding a pressure regulator on the brine-out line and/or foam pipe insulation. What are your thoughts?

 

[Reach4]

Water hammer" is not the term that applies here. That does not mean that your permeate pump is not loud.

I would look into acoustic panels.

Sound Absorbing Panels - The Home Depot

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[Sponsor]

 

[Jimbus]

Water hammer" is not the term that applies here. That does not mean that your permeate pump is not loud.

I would look into acoustic panels.

Sound Absorbing Panels - The Home Depot

Get free shipping on qualified Sound Absorbing Panels products or Buy Online Pick Up in Store today in the Building Materials Department.

www.homedepot.com

Hi there,
Thanks for pointing out my ignorance, easy spot!

Anyway, sound absorbent panels were the first thing I tried for noise. I have inlaid the entire area under the sink with the highest grade sound absorbent panels and then made a few sound boards out of sticking them together back to back and rested those in between the clanking hoses.

Maybe you have another idea?

Thank you for trying!

 

[Fitter30]

Ever talk to factory tech? Brand and model of system?

 

[Jimbus]

Ever talk to factory tech? Brand and model of system?

Hi there,
Yes of course, I called a US Water Systems tech first thing. They didn't seem convinced that it was much louder than a typical permeate pump and generally dismissed the problem. I asked them if there were any similar complaints and they said that permeate pumps typically make sound and its a good way of knowing that they are working. So, the reps were not helpful in finding a solution.

 

[Skeizer2009]

Jimbus - did you ever come up with a solution to your issue? I have an ERP-1000 with the same exact issue.
I've been meaning to install a "sound dampening" layer between the mounting bracket and wall to see if I could reduce the "hammering" sound that is transferring into the basement wall framing and travelling through a good portion of the end of the house where the R/O system is installed, and just realized the majority (if not all) of the annoying sound is transferring from the brine line itself. I'd guess the brine line is bout 1/8"ish, so I might try to find some sort of insulation wrap, as the brine line is clipped along my wall studs and travels along some floor joist cavities - anything to lessen the amount of contact that it has with any walls/flooring/etc. As you know, extremely annoying! Thanks

 

[Jimbus]

Jimbus - did you ever come up with a solution to your issue? I have an ERP-1000 with the same exact issue.
I've been meaning to install a "sound dampening" layer between the mounting bracket and wall to see if I could reduce the "hammering" sound that is transferring into the basement wall framing and travelling through a good portion of the end of the house where the R/O system is installed, and just realized the majority (if not all) of the annoying sound is transferring from the brine line itself. I'd guess the brine line is bout 1/8"ish, so I might try to find some sort of insulation wrap, as the brine line is clipped along my wall studs and travels along some floor joist cavities - anything to lessen the amount of contact that it has with any walls/flooring/etc. As you know, extremely annoying! Thanks

Hey Skeizer,
I put some more sound dampening in cupboard that houses my system along with a foam pipe jacket on the brine-out. I also put a pressure limiter (60PSI) on the intake to the system. I did all that at the same time so I'm not sure which one helped the most, but overall the sound is much less noticeable.
If you're curious about the pressure limiter: I added this because I noticed that the brine-out doesn't get super loud until the system reaches it's full storage volume. These systems at full volume will also be at max pressure. So, putting the limiter just slows the whole thing down and reduces the potential that you are going to have a full tank. If you have a lot of water usage or low incoming water pressure, you probably shouldn't use a limiter.

 

[Fitter30]

Pump gets a max load when tank gets almost full. Try a expansion tank for ro water. What shuts off the pump?

 

[Bob from accounting]

I saw this post, which is seems you have done some thorough homework on this, so this is probably not helpful and you probably already read this. But is was about replacing your check valve. Seems like one of those things that still probably will not fix it, but thought I would point this out. Sorry I can not be more helpful. I am about to install an RO with a perm Pump too, so I found this thread. Ugh, hope it is not too loud with mine.

If RO Makes Noise: - RO-PERM

Find out how to address noise issues with RO systems. Discover solutions for reducing unwanted noise from reverse osmosis water filtration systems effectively.

www.apecwater.com

 

[Bannerman]

A common complaint with permeate pumps is the constant clicking noise while the unit is producing permeate (purified RO water).
The ERP 500 is designed for RO membranes ranging from 10 gpd up to 50 gpd, and so is less noisy compared to the ERP1000 which is designed for membranes exceeding 50 gpd.

I located my RO unit and permeate pump in the basement laundry room below our kitchen. In this manner, we rarely hear the permeate pump unless we are actually in the laundry room while production is occurring.

I suspect the square Black box shown above the membrane housing, is depicting the connections to the permeate pump, but what is not shown is an ASO/ASV (auto shut-off valve) which continues to be recommended even as the permeate pump will stop production when the storage tank becomes filled.

A standard ASV will stop production when the RO storage pressure has risen to 60% of the supply pressure, and will resume production when water use causes the pressure to drop to 40% of incoming pressure. This pressure variance causes production to resume once there has been a substantial quantity of water drawn from the storage tank.

Using only the permeate pump to control production, production will resume immediately when only a tiny quantity of RO water is drawn from the storage tank, which will result in higher TDS creep across the membrane compared to when production time is extended by replacing a larger quantity of RO water.

Because a permeate pump eliminates back pressure on the membrane caused by the storage tank pressure pushing back on the membrane, the pressure differential across the membrane will be increased, which increases the membrane's efficiency and production rate, thereby causing the storage tank to become filled more rapidly in less time compared to when no PP is utilized. This then will reduce the RO unit's run time throughout an average day, and will reduce the amount of rinse water flowing to drain.

To increase the production rate, when the supply pressure is low, a booster pump will be often utilized to boost the membrane supply pressure to 80 psi or greater, by plumbing the booster pump in the line between the carbon block filter and membrane housing.

Because of the elimination of back pressure on the membrane, a standard ASV maybe replaced with a 90% version, which will allow the RO storage pressure to be increase to 90% of the supply pressure, with production being resumed when the storage pressure drops to 70% of the supply pressure.

As your supply pressure exceeds 60 psi when not reduced (psi ?), you may want to increase the supply pressure and replace the membrane with a 50 gpd version, and install an ASV, all of which should reduce the operation time when the PP is producing noise.