inside an American made anti water hammer device

Рет қаралды 284,228

16 күн бұрын

Water hammer is the loud thud from pipework when a valve closes suddenly. It's often caused by the sudden stopping of water with momentum, causing the pipes to jump. It can put a lot of stress on fittings.
The normal approach to fixing this is to provide an air buffer in a pipe or pressure vessel. This device does exactly that in a miniature form. Traditionally a stub of pipe with a cap on the end was used as a crude air reservoir, but there is a belief that the air gets absorbed into the water. I was under the impression that the tiny bubbles of air that often occur in the water supply would refill the air pocket. The piston or diaphragm in dedicated units ensures that the air can't get depleted.
Did you spot me repeatedly mixing up air and water during the video? That's the peril of doing live-take recording with a one-way trip into the device being explored.
I fitted a similar style of unit to try and resolve an issue when my washing machine (laundry washer) is cycling its main solenoid valve, but while it helped, it couldn't cure the decades of random plumbing modifications and unsecured pipes under the floor.
The pressure vessel diaphragm failure I mentioned is fairly common. The usual failure mode is for the diaphragm to perforate, and water to displace the air that was there. If a very brief press on the schrader valve stem results in a squirt of water, then your pressure vessel needs replaced. Some manufacturers recommend checking the pressure from time to time and adding more air if needed.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:- www.bigclive.com/coffee.htm
This also keeps the channel independent of KZfaq's algorithm quirks, allowing it to be a bit more dangerous and naughty.
#ElectronicsCreators

Пікірлер: 1 000

@SaberTail Ай бұрын

Claims to be not an electrical video. Joke's on us. Turns out it's a capacitor, but for water.

@ralphshoop8822 Ай бұрын

proof once again that plumbing and electricity are the same thing.

@markiangooley 15 күн бұрын

@@ralphshoop8822they are surprisingly analogous at least!

@yourimpossibletoisgn 15 күн бұрын

@@ralphshoop8822 I think automatic transmissions show this best.

@straightpipediesel 15 күн бұрын

And that's because long pipes have too much water inductance.

@scottzehrung4829 15 күн бұрын

Great comment!

@michaelgoettsch7744 14 күн бұрын

As someone who not only was a sales man for these products, but also has toured the Sioux Chief factory in Peculiar, Missouri, these things are sold by the tens of thousands. The tube is just spin closed at the end by friction, then the piston is inserted and that traps the air at the top of the closed end. Then is squeezed at the other end to trap the piston. Then, depending on what you ate connecting it to, that tube is soldered to the tee with the appropriate fittings. Available in hose thread, like you have for connecting to washing machines in the US, PEX ends, copper tube ends, and threaded copper tube ends. They make several different sizes with the MiniRester designed to be mounted as close as possible to the problem valve. They also make larger units designed for whole house protection and unuts with internal stainless steel bellows for commercial applications.

@narnbrez 14 күн бұрын

thanks for adding some more context

@squelchstuff 14 күн бұрын

To elaborate on the spin closure - the open pipe is spun in a lathe at high rpm, and then a tungsten carbide tool is traversed across the open end using the cross slide. The tool essentially applies a flat surface to the end of the pipe, but set at an angle. This both heats the material, and pushes it towards the centre. With the right speeds and feeds, a gas tight friction weld is made that closes off the end. Baxi boilers have a similar, but made of steel, part that was manufactured in the same way.

@RicoElectrico 14 күн бұрын

Peculiar, MO is where Todd from Project Farm is :)

@patrickvanden8322 14 күн бұрын

@michaelgoettsch7744 You seems to know your stuff. But why is the plastic piston not deformed? as the soldering puts quite some heat in the squeezed pipe where the plastic piston sits.

@comparedtowhat2549 14 күн бұрын

Maybe you are the sales rep that sent me one of these free for use at my chattering dish washing machine about 25 years ago when I complained at an MEP luncheon in St. Louis that the Watts bladder type I was using was not helping matters a bit. Thank you very much! It solved the problem and it is still in use many washing machines later.

@WanJae42 15 күн бұрын

A lot of people think that the residential water pressure in the US is only 1/2 of what you have in Britain. This isn't true. We actually have the full pressure coming into the house. It's just that we center-tap the supply and split it into two "legs". It's the reason why it takes so long here in the US to fill a kettle. You'll be relieved to know that commercial buildings have three phase water pressure.

@sundog486 15 күн бұрын

Very good!

@davidnull5590 15 күн бұрын

And in the U.S. it Hertz more too, we get an extra 10.

@PRR1954 15 күн бұрын

"commercial buildings have three phase water pressure." Uh, right. But water pumps for RV campers are often built "3 phase" (3 diaphragms) to save the space of a "surge tank" to take out the pulsations.

@deltab9768 15 күн бұрын

We definitely have natural gas in a lot of places, that’s in the high 10’s of psi at the street, and then goes through a regulator to drop it to less than 1 psi. And then there’s an excess-flow valve that shuts it off if a line is damaged and releases an abnormally high flow rate. There’s surprisingly a lot of parallels to the electrical service.

@andyruse4670 15 күн бұрын

It’s also the fact that all fixtures inside of an American homes post 1992 have a restrictor. 2.5GPM or less depending on the fixture. If I used my outdoor spigot which isn’t required to have one, it’d take under 1 second to fill a kettle. Since that faucet rips away at around 10GPM. Edit: Tub faucets don’t have a flow restrictor per se, but modern cartridges do tend to reduce flow unless modified.

@KevinKadow Ай бұрын

The inverted "T" was very common in the USA, near washing machines and dishwashers with fast powered valves likely to cause water hammer. It can eventually lose effectiveness (the air dissolves into the water over time), the fix was to drain down the pipes entirely (so all lines are full of air). When the water is turned back on, the vertical stub maintains an air pocket again for years, if not decades.

@52chevy3100 15 күн бұрын

My house is full of them. And I have to drain everything about every 10 years. Sadly they are all just pinched, and sweated to dead head them. And two have leaked since buying this place.

@cranelord 15 күн бұрын

Issue is that many homeowners are unaware of this being in their homes and stagnant water is stuck in that pipe

@52chevy3100 15 күн бұрын

@@cranelord I learned about mine real quick when water started coming from my baseboards. Lol

@VernKlukas 15 күн бұрын

Here in Canada as well. As far as I know they fell out of favour because they would waterlog as you say and stop working.

@IceBergGeo 15 күн бұрын

@@cranelordthe water doesn't stagnate there as much as you would think. The changes in pressure and flow into and out will clear out a good bit each time it is cycled. Even a little bit will get the chlorinated water into that T.

@farmboy6218 13 күн бұрын

I worked in the Tool and Die department as a Machinist before my health forced me to retire early. This really is a top notch company.

@1978garfield 2 күн бұрын

I am just an idiot home gamer/ DIYer with a house that is over 100 years old. It has been my experience that Sioux Chief products are top notch and fairly priced.

@mikemorgan5015 14 күн бұрын

I my father was a plumber. When I was a kid, he did a lot of new construction work. He taught me how to run copper lines and all the steps involved, including adding air chambers at the end of each run and at every fixture. Just a tee with a 12 inch vertical capped length of tubing as close to the valves as practical. Never had a water hammer complaint. He was religious about flushing water heaters and draining water systems once a year. One reason was to "recharge" the air chambers. We could knock out one of these services in about an hour usually. The extra valves, caps, or plugs he installed during rough in made it quick and easy. Years later, the code changed an all businesses and residences were required to install backflow preventers between the meter and the first fixture or tap. Faucets, water heaters, and pipes started leaking all over town. But not at the places we installed the copper. All those air chambers were evidently enough to handle the thermal expansion.

@f1reguy587 10 күн бұрын

…the backflow preventer is not involved in that issue, we have a double check in our acuflo toby’s not sure all brands do the same, from that toby you will hit a storage water heater at some point, that storage water heater will either have a header tank and ballcock, (natural backflo system) or youll get into mechanical valves eg pressure reducing valve or pressure limiting valve, theres a simple check valve in both of these by the design, there is however a checkvalve in the 3 in one isolater, (filter,stopcock,non return). The “thermal expansion” is monitored by a relief valve and a cold water expansion, obviously boiled water expands, that water expands and overcomes those relief valves spring and drips outside the system. Now assuming in hotter climates theres no huge temperature change in the town supplied cold water i cant see how leaks all over town could be due to installation of a backflow device protecting the towns watermain from peoples property and potential contamination chance. All this was based on a scenario in america where someone was filling a cylinder truck trailer to wash it, the watermain plumbers meantime did work on that water line and backsiphoned the contents of that truck into the water main, when the water repair was done and water returned to normal, some people got chemical burns from using their shower or bath. This is why everything gets a backflo or back siphon control, and each risk has a different minimum requirement, sorry for long reply.

@mikemorgan5015 7 күн бұрын

@@f1reguy587 I stopped reading at your first sentence. When the water comes into a closed system and is heated, it expands. When it expands the pressure increases. Things tend to leak more under higher pressure than lower pressure. The work I did with my father was in the1970s and early 80s. Expansion tanks pressure reducing valves, and backflow preventers weren't required then in our city. Expanding hot water was free to push back a bit into the main. Not much, but it wasn't a closed system. It was free to expand. The backflow preventer stops that. The expansion had to go somewhere. the relief valve on a water heater is generally 150 psi. Mains pressure was 40 -60 depending on where you lived. That's a 90 to 110 psi difference before the relief valve activates. See last sentence first paragraph.

@KeritechElectronics Ай бұрын

Surge protection device, only for plumbing rather than wiring, and fully reusable too :)

@bigclivedotcom Ай бұрын

It's literally a decoupling capacitor for water.

@KeritechElectronics Ай бұрын

@@bigclivedotcom this one is a bit too small, it's good for transient suppression but not pressure stabilization. Large pressurized tanks, on the other hand, are a good counterparts - where pumps acts as generators or transformers, and check valves acts as rectifiers.

@G3rain1 2 күн бұрын

@@KeritechElectronics It's MEANT for transient spikes in pressure, a.k.a. water hammer. And it's an appropriate size to handle that.

@Chrisamic 15 күн бұрын

Pretty commonly used here in Australia. They make different types depending on what your mains pressure is. High pressure areas need a stronger water hammer arrestor. Some actually do seem to have a spring in them, you can hear it scrunch when they operate. Apart from the noise, a water hammer will eventually damage a copper pipe because the hammer/movement causes the copper to work harden and eventually it will get fatigued and crack. Similarly, plastic pipe gets more brittle as it ages and more likely to crack from a water hammer. As a metal worker, that one looks like it's friction welded on the flat end. They're made out of a simple piece of copper tube. It's a common manufacturing technique. For the threaded end the tube is heated and then pressed into a die to neck it down and then a thread can be cut on the narrow part since the material wall is now thicker. For the flat end, it's heated and pressed down flat but with a very narrow tube. A conical die is then spun very fast to friction heat and weld the narrow pipe shut. That's why it looks the way it does. It is literally called "friction welding" and is very economical to do at scale since the tooling is usually simple and you don't need any shielding gas. For the necking down operations sometimes they are heated very quickly with a very hot flame (oxy/lpg or similar) but sometimes they just spin the part very fast as they push it into the die. You can normally tell which one it is by looking at the marks left by the tooling (which is the giveaway for the closed end in this case).

@deltab9768 15 күн бұрын

I definitely have seen a splice in an irrigation line fly apart from waterhammer. It can definitely break something if the pressure peak is high enough or as you said the system is worn out by it over time.

@AgentOffice 14 күн бұрын

How do you pressurize it at the top

@bogdan_n 14 күн бұрын

WTF are you talking about? These are made from a copper blank (technically a thick copper coin) which is formed into a single side ended tube by pressing into a die, or deep drawing (that divot on the sealed end is from the plunger used to shoot the tube off the mandrel), then the plastic puck is inserted and the neck is formed by roll forming it in a machine like a lathe that has rollers instead of a cutting tool. Just search how high pressure gas cylinders are made.

@Chrisamic 13 күн бұрын

@@bogdan_n I'm quite aware of how pressure vessels are made, but they are made from a billet, not a disk. You can see the spall marks on the cone, and it's hollow. You can also see the copper carbonate degradation products on the inside of that end, ergo gas heated.

@Chrisamic 13 күн бұрын

@@AgentOffice As you can tell from when it was opened, it's at 1 atm. The water pressure pressurises the bulb. This one is probably intended for relatively low pressures, maybe 220 kPa, and that might be why it didn't work for the previous owners.

@RT-qd8yl 15 күн бұрын

I've got drawers full of these at work. I test and refurbish dishwashers/washing machines/refrigerators etc, and these are a necessity on the outlets of our water manifold system. They're also really handy if I need to make some kind of adapter or coupling; just cut the ends off and sweat them onto some pipe!

@gary_rumain_you_peons 14 күн бұрын

Now if someone would invent a solenoid that doesn't slam shut so quickly, then we could all get some sleep.

@RT-qd8yl 14 күн бұрын

@@gary_rumain_you_peons I think the only thing holding them back is cost; we've got EEV refrigerant solenoids and expansion valves that open/close MUCH more gradually than an electromagnetic solenoid, but they're also 3-4 times as expensive. They'd probably have to be engineered differently to hold up to water rather than nearly sterile refrigerant as well.

@gary_rumain_you_peons 14 күн бұрын

@@RT-qd8yl OK, thanks.

@JamesPotts 15 күн бұрын

My highschool physics teacher had a glass tube under vacuum with a small amount of water in it, to demonstrate water hammer. It was impressive.

@Chrisamic 13 күн бұрын

I've been trying to figure this out. Water in a vacuum is a gas. How was it demonstrated? Physics teachers always have lots of cool demo apparatus. They often don't like explaining them however...

@robertt9342 13 күн бұрын

@@Chrisamic. I agree, suddenly increases of pressure would just cause it change from gas to liquid in the setup described.

@JamesPotts 13 күн бұрын

@@Chrisamic if I recall correctly (which is questionable after 34 years) it looked professionally made. He wouldn't let kids handle it, because if you weren't careful, the water could smash its way out the end of the tube.

@leocurious9919 12 күн бұрын

@@Chrisamic You apply a shock load, this will accelerate the container away from the water. Due to the vacuum, it is easy for this to happen, as there is no air pressure you would need to overcome. Once the acceleration of the container stops, the acceleration of the water takes over until it smashes back into the container. The gas bubble collapses into itself, as it is only made of water vapor, so no gas cushions the blow.

@Natediggetydog 11 күн бұрын

You can actually feel the water hammer if you put water in a small plastic hose like what you’d have in a chemistry lab. Fill it about half way, put your fingers over the ends, and tilt it back and forth.

@pikafu6641 15 күн бұрын

I do really enjoy your videos where you're a little more out of your element. Makes me feel like I'm not alone in not knowing how anything and everything works. The genuine joy and inquiry in your voice as you ponder how it works always makes me smile!

@RedKincaid 13 күн бұрын

I absolutely love people who get excited about what they don't know, the desire to learn is such a great trait

@mikebashford8198 15 күн бұрын

Many years ago I had a tour of Bonnington hydroelectric power station. They have a gigantic version of this device - a surge tank (difficult to see but I would imagine about 20 feet diameter and 30 feet tall) fed by 2 6ft diameter pipes.

@bigclivedotcom 15 күн бұрын

There are videos of surge tanks operating on KZfaq. Quite scary amount of water.

@michaelkhoo5846 14 күн бұрын

Ah yes the Obere Wasserschlosskammer: kzfaq.info/get/bejne/nLCGdc-ZzNqdmmw.html&ab_channel=EdgarM%C3%BCller

@straightpipediesel 15 күн бұрын

Air-bladder expansion tanks are now required pretty much everywhere in the US. If you have city water, regulations require a backflow prevention valve at the street, for sanitary and anti-terrorism reasons. An expansion tank is installed at the water heater to prevent high pressure developing due to temperature changes. If you have well water, you have a giant bladder pressure tank unless you have a fancy VFD-based well pump.

@kittytrail 15 күн бұрын

only them 'merkuns would say it's for anti-terrorism reasons. looks like they've bought their masters propaganda on instalment for the rest of their lives... 🤡🌎

@JJRD222 15 күн бұрын

😂 antiterrorism

@dougerrohmer 15 күн бұрын

@@JJRD222 I think that's what terrorists like to do - how can we simply and cheaply screw these guys in a new way that they don't see coming? Who would have thunk back in August 2001 that a bunch of aircraft will be hijacked and buildings will collapse?

@dashcamandy2242 14 күн бұрын

The pressure tank on a well serves two basic functions: maintains steady water pressure throughout the pipes, and acting as a reservoir for the pump. The well pump circulates on/off to fill the pressure tank as needed in a basic single-speed pump setup. Fun fact, a 2021, 110-volt water pump is more efficient and moves more GPM than the 220-volt 1980s pump it replaced. Most times when our pump stopped running during all those years, it was either a worn-out pressure cutout switch, or a failed starting capacitor.

@stephenj4937 14 күн бұрын

I have city water but no backflow prevention; those are only required if you have an in-ground irrigation system. And because there is no backflow device there is also no expansion tank on the water heater.

@johnwiley8417 15 күн бұрын

1:01 Those of us who are on well water (Emergency system for my family. Primary is treated "city water.") usually have one of these to smooth out the water pressure coming from the well pump. They still allow 10-15 psi change as the pump switches on and off. The large ones used with well pumps have the air pressure range stamped into them, so you can refill the air above the diaphragm.

@deltab9768 15 күн бұрын

Yup. Probably a big tank for off-and-on water usage and pumping, and then these little guys to absorb the shock when a valve closes.

@brianleeper5737 14 күн бұрын

My well has a constant pressure, variable speed Grundfos pump, and while it has a pressure tank, the pressure tank is small, maybe 1 gallon. When I say it's constant pressure, that's exactly what it is--it maintains 70PSI or close to it at all times. This pump is also capable of being run off a 12V inverter with a step-up transformer (to go from 120V to 240V), as it only consumes about 800 watts when one faucet is open and, being variable speed, doesn't have a huge start up surge.

@Dwigt_Rortugal 14 күн бұрын

Right, on our well we have a large diaphragm tank that gives us pressure at the tap. They're almost all that way here. As Clive alluded to, we also have a smaller diaphragm tank on the main hydronic heating pipe. There's also a PRV as he mentioned.

@jttech44 10 күн бұрын

You need a larger pressure tank, likely much larger. That plus a regulator and you'll have water pressure for days.

@mrDarktrooper 15 күн бұрын

The third and often overlooked solution, if you don't wish to modify your plumbing, is to simply crack open the valves to the washer just enough to limit the flow rate to where the velocity of the water in the pipes is not enough to cause a hammer situation. The only side effect is that your washer will take a little more time to fill.

@andymerrett 14 күн бұрын

Yes if you want greater wear and tear on the valves.

@MrMichiel1983 14 күн бұрын

@@andymerrett why would that cause greater wear?

@paulmeynell8866 14 күн бұрын

@@MrMichiel1983 it’s a solenoid valve it’s on or off!

@James_Bowie 14 күн бұрын

While this works, I have found that it can eventually burn out the solenoid because it's working to hold the valve open for far longer than anticipated.

@pootispiker2866 14 күн бұрын

If your washer is new enough it will notice the lack of flow and error out

@petersage5157 15 күн бұрын

I've put in some time in the home hardware retail industry and I recognize Sioux Chief as a common brand of plumbing fittings. As I understand this (and my understanding could be completely wrong), hammer arrestors are made and specified for ranges of pipe volumes; presumably the installer does some back-of-the-envelope calculations and selects whatever arrestor is the best fit, just like selecting a debounce capacitor for a switched input.

@michaelgoettsch7744 14 күн бұрын

@@petersage5157 this is true, however when it comes to residential water piping in the United States, almost all fixture supply lines are 1/2 inch copper tube size regardless of the actual material used for the pipes, so these size water hammer assessors are all the same size. For larger applications they are indeed sized based on pressure and pipe size.

@Dwigt_Rortugal 14 күн бұрын

It strikes me as offensively dark humor to go to a retailer and buy a "closet" (i.e. toilet) flange that is from the Sioux Chief brand. Last time I installed a toilet in our house, I chuckled. So offensive, but also just odd.

@petersage5157 14 күн бұрын

@@Dwigt_Rortugal The company name is actually intended to honor the culture of the Lakota. All too often, offense is only in the eye of the beholder.

@randycarter2001 14 күн бұрын

The trouble with the dead end pipe is after time the air would diffuse into the water and eventually disappear. And yes, they don't allow it in modern plumbing inspections.

@LogicalNiko 14 күн бұрын

100% accurate. The inverted T was extremely common in homes from built/renovated 1940s to about the 1980s when arrester devices became common. Most of the homes throughout the Midwest and west coast build in the post World War Two boom had inverted T setups. Surprisingly in the New England coast you saw this a lot less. Many more towns tended to have lower pressure supply systems or they predated the requirements for back flow prevention systems on the city water supply. So many houses just depended on the water main to kind of act as a buffer or even the water heater (and usually washing machines were in basement close to the main supply). Of course in cheaply built homes with PEX you now get people complaining about “things moving in their walls” as badly secured PEX flops around.

@mouseTN Ай бұрын

Larger air bladder tanks are also commonly used on water supplies that come from a well. They provide water pressure without forcing the well pump to run constantly.

@YagiChanDan 15 күн бұрын

Also known as accumulators....or super capacitors. We use them as an alternative booster pum0s.

@louf7178 14 күн бұрын

Those might also be called compression tanks.

@50srefugee 14 күн бұрын

My folks had one. It was a tank, about two feet across and four or five feet high. I learned that every few months, you have to turn off the pump, open a bleed valve, and let the tank drain out to about half full. Otherwise, the pump would cycle continuously. It turns out that the air in the tank would actually dissolve in the water, and get pumped out to the house. (Originally, it just had a pressure gauge, which you would remove to allow air in. I installed the bleed valve on a tee. Pretty proud of myself for that....)

@YagiChanDan 14 күн бұрын

@louf7178 the surge arrestor Big C was playing with might he. Not what we're talking about here though.

@nraynaud 15 күн бұрын

generally we try to put the device in a straight line with the pipe, since it's an inertia issue (the water doesn't want to brake), you're dealing with water that doesn't like taking a turn either. So you put the device is a straight line, it gets most of the pressure spike, and when the water has dealt with its feelings, it's ready to turn gently and do nice work in the washing machine. Otherwise you divide the pressure spike between the washing machine and the device.

@bigclivedotcom 15 күн бұрын

That makes sense.

@Tranquility-Base_on_the_move 14 күн бұрын

That is what I was thinking too.

@nickwallette6201 9 күн бұрын

"... has dealt with its feelings" ... haha love it.

@tjsynkral 15 күн бұрын

For a moment I thought this was a rude product and you were speaking in code again.

@bigclivedotcom 15 күн бұрын

I bet a few people have used it for that.

@deltab9768 15 күн бұрын

Anything is a “rude product” if you’re brave enough. Just ask Tom Bomdildo.

@michaelsimpson9779 14 күн бұрын

Water Hammer.....lol Benny Hill would've (probably did for all I know, he was slightly before my time) had a field day with that. I'm not all the way through the video yet, do we get to hear Clive say the word, "moist" again as per the tiny electric motor recovery video...?

@AlbinoAxolotl1993 11 күн бұрын

Guess that's why bubbler pipes are sometimes called a hammer pipe.

@barrieshepherd7694 Ай бұрын

Good to see your hand on the mend.

@Coconut-219 15 күн бұрын

"plumbing new depths"

@bigclivedotcom 15 күн бұрын

I like to throw in a plumbing component from time to time.

@massimookissed1023 14 күн бұрын

A simple dead-end pipe without the puck can have the problem of the air pocket gradually dissolving into the water. That puck will prevent that, while still just using air as a spring.

@silentbob1236 14 күн бұрын

I am not a plumber, but a controls engineer. The diaphragm is not necessary. We add several vertical tubes in our system that naturally collect gases entrained in the fluids. The result is a cost-effective buffer that automatically maintains itself and helps reduce pressure spikes throughout the system. I also looks like they stir welded the end to seal it.

@stargazer7644 12 күн бұрын

"I am not a plumber, but a controls engineer. The diaphragm is not necessary." That's because you're not a plumber.

@233kosta 15 күн бұрын

Ooh! Traveling shockwaves! My favourite!!! By the way that's what water hammer is. A sonic shockwave. They can get pretty strong too.

@oikos_9000 Ай бұрын

Maybe having an air pocket above the water in a blind pipe is promoting something grim to grow? That could explain why the version with a diaphragm was safer - no space for an air pocket to form.

@g3neration216 15 күн бұрын

so now plumbers just install thermal expansion tanks above your water heater with pre-set pressure to about 40 psi. Then they turn the water on and the tank immediately absorbs it's maximum capacity and the bladder hits the expansion limiter (if it's a nicer one with one of those) and does nothing. Now you have another tank full of stagnate water likely growing some funny stuff.

@whitesapphire5865 15 күн бұрын

Legionnaire's disease springs immediately to mind, followed by listeria and salmonella..... Which is also why water from the hot tap is not to be used as potable water 🚰

@jonathanbott87 14 күн бұрын

@@g3neration216 what they're saying is the bladder tank doesn't have an air pocket touching the water so that *could* make a difference.

@parmesanzero7678 14 күн бұрын

Could produce a backflow issue to boot.

@ssl3546 12 күн бұрын

Yes, specifically legionnaire's disease.

@CKOD 15 күн бұрын

I think the most impressive thing here is Clive's ability to not mangle the pronunciation of Sioux. Usually Native American based words just have Europeans falling on their face. Like when Brits laugh because people try to pronounce all the letters in a town name when its actually made up of 50% silent letters, but usually we get to do the laughing for once. "Whats wrong, Sioux, Iriquois, and Navajo too hard to pronounce?"

@tsobf242 15 күн бұрын

sioux is actually a french exonym, so he might just recognize french words

@bigclivedotcom 15 күн бұрын

I did google the pronunciation before making the video. My guess was correct.

@Poodleinacan 15 күн бұрын

It's Iroquois 😂 I guess you made a typo lol

@manicminer4573 14 күн бұрын

We had a pop star in the 80s called Siouxsie Sioux, so those of us of a certain age do know how to pronounce it!

@andymerrett 14 күн бұрын

Wow, how many nationalities/continents can you stereotype in one paragraph?

@rjk7104 15 күн бұрын

You can see that the area is damp above the plunger and has corrosion, which to me means that the o-ring seal leaked and let water through. These normally have a nitrogen precharge above the plunger and that is why the top has that button seal thing. The one you have there is designed as a retrofit option for existing clothes washers, as indicated by the "GHT" style threading, AKA Garden Hose Thread, which is commonly used for washing machine hookups in the US.

@stargazer7644 12 күн бұрын

Why would it be damp and corroded? It's a new device.

@rjk7104 12 күн бұрын

I suspect it is in fact very used, even if it were billed as "new" on the eBay auction he bought it from.

@Zanthum 15 күн бұрын

In the old style the same thing happens as what happens with the bladder tanks for the water heaters: the water absorbs the air in the pipe and replaces the volume with water eliminating the spring effect. A larger version of the same system is used for well water systems so the well pump doesn't cycle every time you turn on the tap and that is probably the most common failure mode. In a pinch you can refill the backside of the bladder with air and repressurize it, but it is a very temporary solution as it will fail the same way again, the steel on the air side of the bladder is not protected against water contact, and you will have trapped water in an environment condusive to growth.

@fengatormx6 13 күн бұрын

As a maintenance person I think you just sold me on buying a bunch of these to install on washing machines. I constantly have issues with water hammer damaging my solenoids, and on some machines it leads to flooding when they cant turn off.

@LethargicSquirrel 14 күн бұрын

I'd never experienced such noticeable water hammer until I moved into the place in in now. Every time the washer valve closed, it sounded like the pipes were coming apart. I bought two similar to these a couple years ago and haven't had any problems since. The peace has been restored!

@craxd1 15 күн бұрын

In hydraulics, they're called accumulators, but that's a very small one. Most, like these, will use a piston with and without a spring.

@rwbishop 15 күн бұрын

In the hydraulic world, known as an 'accumulator'... and a somewhat crude one at that. In the plumbing world they were ofter called 'water hammer arrestors'. They act similar to a capacitor in electronics. The little vertical dead end pipe versions were usually located just out of sight back in the wall, and worked well enough; but every year or so, you needed to turn off the water and open all the faucets to drain everything, and allow air back in the arrestors'. It wasn't that big of a deal, but people just didn't do it.

@bansheedearg 15 күн бұрын

Indeed, and to answer Big Clive's question, they start with air and fill up over time because the water will dissolve the air, making them ineffective. To remedy, you have to turn off you main water supply, find the highest and lowest taps in your system, and open them to drain as much pipe as possible. They are simple, cheap, and rock solid (no rubber or seals, just an air pocket). Maintenance is super important, a hot water heater has an anode they you should replace every so often, in addition to draining junk from the bottom.

@evanschwartz5526 3 күн бұрын

I used to live in a scholarship hall that had this exact water hammer device attached to our commercial dishwasher. Fascinating to learn how it works! Wonderful video, thank you very much for the knowledge you’ve given me :)

@protowave 7 күн бұрын

a similar device, referred to as a bladder or piston accumulator, is also used in hydraulic applications. well, i guess this is hydraulic as well since there's water involved. one of the most interesting uses is on some launching roller coasters, where several very large accumulators are used with nitrogen as the air spring in one side, and hydraulic oil in the other side.

@dang495 15 күн бұрын

I had these on the back of my washing machine. The "professional" installers of my new washing machine didn't take them off and put them on the new machine. They just hauled them away with the old machine.

@transmitterguy478 15 күн бұрын

Hey Clive, that would make a heck of a bong.😎

@dr.deborahkatharinestevens318 14 күн бұрын

I recall being so shocked when reading that The Elizabeth Tower at the Palace of Westminster is home to the biggest bong in London!🤯......but perhaps that may explain "things"🙄

@railgap 14 күн бұрын

Also I love the conversations / comments your videos engender.

@helipilotuh1 13 күн бұрын

In older homes you cold also get a pulsing harmonic if you barely cracked a valve sometimes. Terrified me when it happened to me at my grandparent’s house. Sounded like every pipe in the house was shaking.

@masteryoda394 15 күн бұрын

In french the phenomenon is called " coup de bélier" and devices to deal with it are "antibélier"

@KernelLeak 15 күн бұрын

Am I assuming correctly that they're also sold by "Sous-Chef" instead of "Sioux Chief"? :D

@Richardincancale 15 күн бұрын

Being hit by a ram - male goat variety!

@masteryoda394 14 күн бұрын

@@Richardincancale sort of, yes

@masteryoda394 14 күн бұрын

@@KernelLeak never heard of Sioux chef, do people really say that? Interesting

@Zoroaster4 14 күн бұрын

@@masteryoda394I think it's a joke. Sioux is the name of an American Indian Tribe and their leader was obviously the chief.

@benespection 15 күн бұрын

They would likely have a hole in the end for air to escape during assembly, inserting the "puck" as you say, then once it's positioned to a point where there's enough "cushion" they would seal the end off.

@bigdave6390 14 күн бұрын

Way back when I was a plumber and still worked with copper pipe, I had to fabricate these air chambers. Usually used a 3/4 x 1/2 x 1/2 tee. 1/2 being the water supply and the 3/4 being the air chamber. 12 inch piece of 3/4 pipe with a cap. It had to be vertical and at every appurtenance.

@richardhall5489 14 күн бұрын

Domestic plumbing is typically a small scale version of the supply / sewerage system - fresh water is pressurised, waste water (most countries) uses gravity flow. The equivalent of water hammer in large pipes is not just a louder version of the domestic banging sound. If you close a valve too quickly the resulting shock wave may rupture the pipes. In order to avoid this valves are closed very very slowly (there's maths involved). And if it's a valve in the middle of a long pipe run there's a danger of collapsing the pipe by causing a vacum on the downstream side!

@Pyroteknikid 15 күн бұрын

Not to be confused with "Sous Chef"

@joeboatwrench9315 Ай бұрын

4:30. The hand looks lots better. 😊

@IceBergGeo 15 күн бұрын

This may have been prior to the hand receiving it's wound... Originally privately posted a month ago, or so...

@Puffalupagus360 14 күн бұрын

Clive remember that when you explained how the expansion tank work you explained that when the water heats up it expands and presses on that diaphragm. That means that when the water in the system cools down it's going to push back to a certain extent. That naturally happens every water heating cycle so you're moving some water in and then back out of that pressure vessel preventing it going dangerously stagnant.

@dantuck5242 11 күн бұрын

You are spot on sir. Some do contain springs. The top end was spun closed. The only thing I could enlighten you on is the reason we no longer use air chambers is because over time water will absorb the gasses in the dead end and become ineffective, making it necessary to periodically drain the entire system to refill the air chamber.

@bigclivedotcom 11 күн бұрын

Hi Dan. Long time no see. (Great beard.)

@LawpickingLocksmith 14 күн бұрын

Civilised areas of central Europe do not really get water hammer. I first experienced this in Australia and bought such a device to find it made hardly a difference. Surprised yours did not have a spring to return the plunger. Probably designed to last less than 10 years. Now you have scored 2 O-rings and some copper to recycle.

@mlies37 15 күн бұрын

i’d think something this simple could just be in every washing machine for 3 cents extra and save everyone a bunch of trouble

@problemsolverstoothlessold5803 15 күн бұрын

They are part of laundry boxes (hot and cold supply valves and a drain) for your clothes washer here in the US.

@mlies37 15 күн бұрын

@@problemsolverstoothlessold5803American dryers have a water supply? 🤯

@tomschmidt381 15 күн бұрын

Or just slow down the solenoids, we did not have a problem until we purchased an LG front load washer.

@mattmanyam 15 күн бұрын

@mlies37 yes, as a "steam" function, for static reduction and "quick refresh" of items you may not want to wash immediately (sweaters, for example).

@adamhutton4165 11 күн бұрын

Interesting to know how they're made but as far as utility, this thing changed my family's life. My washing machine used to made such a "bang" that it would rattle the walls and wake the family. Plumber wanted a bunch to fix it. This thing cleared it up instantly. I can't recommend it enough if you've got the dreaded "water hammer" problem.

@Transit_Biker 14 күн бұрын

These are great. I’d recommend them for toilets, washers & sinks. Will extend the life of your toilet fill valves (plastic) & your washer hoses.

@andrewsmythe-lg5ce 15 күн бұрын

I was wondering if there was a huge spring, it might not have ended so well, but it wasn't live, so must have ended well, as it did.

@jonathanbott87 14 күн бұрын

Nah, that would have been the *perfect* ending for Clive's videos. 😂

@CanizaM 14 күн бұрын

Look at the area of the piston, and consider what a typical water pressure is, to estimate what force a spring would have if there was one present. As this is a closed device, there would also have to be consideration of whether there is pressurised gas in the space above the piston.

@andrewsmythe-lg5ce 14 күн бұрын

@@CanizaM Pressure of a water hammer*

@JendaLinda 15 күн бұрын

I have never seen such device. Washing machines are usually connected to the water supply using a flexible hose so that probably reduces the pressure pulses.

@Tomd4850 15 күн бұрын

Nope, those flexible hoses don't provide very much expansion action to soften the blow of the near instantaneous valve shut off. Newer washing machines are supposedly much worse than older ones, due to sometimes quickly alternating valves on and off to balance the water temperature. I have polybutylene plumbing in parts of my house, so installing water hammer arrestors on both lines just before the flex was a necessity. It's still highly recommended for all newer washing machines and dish washers to increase the lifespan of your pipes and fittings.

@disjustice 15 күн бұрын

15 years ago when I bought I new machine I didn't get them. The last 2 machines I bought since then (one for each of 2 moves in the last 10 years) the installer insisted on installing them. May be a change in code here in Massachusetts.

@michaelgoettsch7744 14 күн бұрын

@@JendaLinda here's a secret. Most of the time when those hoses fail, it is due to the forces exerted on them by water hammer over time.

@JendaLinda 14 күн бұрын

@@michaelgoettsch7744 Something else usualy fails before the hose would.

@JendaLinda 14 күн бұрын

@@disjustice These are just not needed here. European washing machines are probably built differently.

@CedroCron 14 күн бұрын

Always wondered what was inside but didn't want to destroy one to find out... Thanks Clive!

@sziltner 14 күн бұрын

👍🏻 Love the change of pace! 👍🏻

@phonotical Ай бұрын

Made in the USA, and not entirely plastic? Wow 😂 Best way I've found to avoid water hammer is just to close the tap slowly, maybe make sure you don't have weak pipes

@volvo09 15 күн бұрын

Can't really do that with washing machines though, they often bang closed, but they seem to have gotten better these days.

@PainterVierax 15 күн бұрын

@@volvo09 absolutely. The issue is mostly solenoid valves inside automated machines. And yeah I can confirm they got better these days: I changed my 30 years old dishwasher few months ago and the classic "clong" from the water hammer is gone now. My washing machine never had this problem though, probably because this is a more recent equipment bought when moving to the house 15 years ago.

@rarbiart Ай бұрын

4:10 having a fountain in the house would be quite mundane!

@OOZ662 13 күн бұрын

Use one of these on a bidet that was honestly very well designed in every aspect except the water tank section. It has a substantial (for the size of the unit) water tank to it so that it can keep a decent amount warmed, and yet it will only run for about two seconds before opening the intake valve (and by the sounds of it, even turning on an intake pump), taking in water for about two seconds, then slamming the valve shut, then repeating until the user is finished. It was beating the everloving hell out of the pipes. I added both this sized mini-restor and used a valve meant for showerheads to limit the flow rate; now it just slams as much as the toilet does when it finishes filling.

@RODALCO2007 15 күн бұрын

Great autopsy, always wondered what was inside these devices.

@zncon 15 күн бұрын

For how much these dang things cost, I was really expecting something a bit more complicated.

@tomschmidt381 15 күн бұрын

$15 US or so on this side of the pond.

@hammerth1421 15 күн бұрын

Could the top be friction welded shut?

@bigclivedotcom 15 күн бұрын

Not sure.

@DelticEngine 15 күн бұрын

Thanks very much for posting this video, Clive, I had often wondered what was inside such devices. Not knowing and the lack of information as to what method a particular device used caused me to not take the chance in purchasing one. I ended up restricting the flow to the problem machine to limit the hammer and still allow the machine to operate without error. There is another way to stop water hammer and that is to modify the solenoid valve itself so it opens and closes in a more controlled manner and eliminating the hammer. This is done by modifying the hydraulic apertures inside the valve. I appreciate that your primary focus is on electronics, a video on a solenoid valve and its modification would be very interesting.

@jacobs7764 11 күн бұрын

I drove past the Sioux Chief plant all the time growing up, and always wondered what they made in there. Never would have guessed a Brit would be the one to tell me. Neat video, thanks for the info!

@pomonabill220 15 күн бұрын

If that was new, or still pressurized, the gas in the tube could have been dangerous when you cut it. It could have about 60-100 psi of gas in it (either air or nitrogen). These usually fail because the o-rings become damaged and the gas leaks out so the piston is pushed to the end and no hammer arresting is done so they need to be replaced. The strange blob in the end is probably a copper seal, either welded or spun on after it is pressurized.

@dennisphoenix1 15 күн бұрын

The average pressure in the UK IS 3 bar or 44 psi. Any pressure above 45 psi would render it useless.

@makinbac0n 8 күн бұрын

Thanks for reminding me about water hammering. My dishwasher keeps blowing out the sprayer on my sink faucet. The water hammer makes the cheap plastic sprayer split on the seams. Sounds like I need what you got. Guess I have some plumbing to do.

@Satchmoeddie 13 күн бұрын

We have hot water, condensation hot water heating systems as well as steam heating. We use a pressure vessel on those too. My father was a pretty good plumber, and a professional hydrologist. The dead end anti-water hammer piping he installed actually made the water hammer effect even worse. They still sell 1/2" to 3/4" and 3/4" to 1" dead end pieces, or they used to. I bought the Sioux Chief arresters for the washing machine solenoids.

@jimbodee4043 14 күн бұрын

Interesting as usual Clive thanks for the video.

@korishan 14 күн бұрын

I use one of the Dead Head hammer arrestor designs. In my primary hub I have a 1.25" ball valve for the main flow, then it Tee's left/right. The path to the left has another Tee down that goes to my house. Then continues another Tee which feeds a "true" 3/4" hose fitting, continues to another Tee, which is turned up/down in relation to the others, with another drop but this one is an open 1" ball valve. The portion that goes up goes into a 1ft piece of dead-ended pipe. Works really well and I rarely have any hammering. Every few months I'll go out and turn off the main valve, open the end valve to valve to allow the water to drain from the dead-end to flush out the stagnate water and replenish the air. Over time w/o a diaphragm, the air will eventually be pushed back into water. This is what happened with old water well tanks and they had to be "bled" every year to replenish the air supply.

@kevinyancey958 15 күн бұрын

I still run a piece of vertical pipe with a dead end. As long as it's vertical, it will trap air and arrest water hammer. Water hammer can cause damage to any fixture attached and even to the pipe and water heater. In homes with backlog prevents, you have to put an expansion tank in the hot water line. The best way to mount expansion tanks is with the threaded end down. If the bladder fails, the water stays in the tank. If you mount it horizontally, the water will push against the bladder on the bottom side and the air will push against the top. It will fail much faster than vertically.

@Livingreciever 11 күн бұрын

I dont know why but I always love seeing the little wavey "M" burn mark in the middle of Clives table.

@w49660 15 күн бұрын

We have these on our washer connections and they work great for us and got rid of the water hammer from that.

@AlexSwavely 9 күн бұрын

The "just a piece of pipe" arrangements aren't filled by bubbles in the water, but when the system is initially filled with water (and any time it's shut off at the main valve) it just gets ambient air trapped in it.

@SirBoden 15 күн бұрын

I have two dead end water hammer buffers in the wash room. Once a year I drain the two lines completely to refill the vertical section with air. They are 1.5” OD x 2’ long black iron pipe.

@Dragonwarrior125 13 күн бұрын

Oh hey!! I worked at the place they made those! Short walk around the block to my house. (and a cold one in the winters. Good folk tho, they'll make you throw your bicycle in the back of a truck and drive you home) I myself worked on a number of things there, but "my" machine made the ones that were a bit different from that (Tub/Shower Valve Tee), but same fundamental principle to it. As already mentioned here, the back end is spun closed with just metal rollers, essentially, and the ones i did pressurized. Each one is also pressure checked too, by hand. They explained exactly what you had here about how they work as part of my training. The text stamped around the edge there has the size and date stamped on there, so they can track down when stuff fails, since they're supposed to have a lifetime gauruntee. July 2013 by the looks of things. And let me tell you, besides the heat of a humid Peculiarly Miserable (;D) summer, applying the stickers sucked the most. You essentially plucked them from a roller with the side of your pointer finger, and then curled them around. Peeling 1,000s of them off makes that patch of your skin STING I tell ya what.

@seanstrain1 10 күн бұрын

Exceptional explanation!

@DominikJaniec 13 күн бұрын

neat disassembly! thanks :)

@etatsopa 14 күн бұрын

We’ve got two sets of two water tanks collecting rainwater. One of the pumps has a large pressure vessel on the top of it, with some pressurised air in it. The pump runs until the pressure reaches its upper limit, compressing the air at the same time. The air pressure forces water through the pipes when a tap is opened, until the pressure reaches the lower limit, and the pump comes back on. It means the pump doesn’t need to run 100% of the time when a tap is open.

@BTAJoe 15 күн бұрын

Verrry effective! I use them on my washing machine.

@endcgm9277 9 күн бұрын

I’ve installed dead heads at fixtures in all my plumbing new and rework projects. I’ve often had complaints of water hammer and noises in the walls eliminated with just an inverted dead end pipe. Stops Pex from moving around so much as well. Quite simple to recharge the air. Drain the system at the water heater, as you should once a year or two anyway.

@dnel83 14 күн бұрын

I installed one of these 2 years ago between my washing machine and the feed pipe and it solved my water hammer problem. Assumed it was a very simple device inside and i was correct!

@wisteela 14 күн бұрын

Interesting and educational. Nice simple device. That pipe cutter is cool too.

@a-borgia4993 14 күн бұрын

We (in Fort Wayne, IN, USA) had one installed in our old house.... It worked great to reduce "pipe noisy vibration" when dishwasher or clothes washer opened and closed its valve. (likely a clamp loosened somewhat and the arrestor fixed it. The end is "hot formed"

@Milosz_Ostrow 11 күн бұрын

I've found that substituting PEX tubing for copper or iron pipe works great for eliminating water hammer. If one has a run of the stuff half the length of one's house, it expands sufficiently to act much like the Sioux Chief Mini-Rester. Where I had a substantial rattle and banging whilst running the shower, after I replumbed with PEX there still is an oscillation in the system at times, but it is just a gentle chuff-chuff-chuff.

@paulphillips675 14 күн бұрын

Donkeys years ago I had a problem with pipe hammer and my grandfather suggested adding a vertical blanked off length of pipe. Added about a 12 inch length with a stop end off the rising main to the water tank in the loft (before we had a combi) which solved the problem. My understanding is not that the blanked off pipe filled with bubbles from the mains but because it is vertical the rising main water rushed in to fill the pipe but the air has nowhere to go, e.g. it can’t work along the pipe to a tap to be released later because, so you are left with a column of air above the water (just like submerging a glass open end down in a bucket of water) which compresses to absorb the pressure changes that cause pipe hammer. My grandfather was not a plumber but a very able handyman!

@ncot_tech 15 күн бұрын

20 years ago I used to work in a very old building in the Lake District, I also lived on site. The tap in my room had the most spectacular water hammer whenever I ran the cold tap. You could hear it all through the floor I was on. It made the tap vibrate if I got the flow just right 😆

@tomcripps1876 15 күн бұрын

interesting little device :D thanks clive

@Legomanfred 14 күн бұрын

I've had one under my sink for years. I knew what it was for, but never knew how it worked. Great video. Thanks for sharing. 👍

@jonathanbott87 14 күн бұрын

Under the sink might be for the dishwasher too

@Legomanfred 14 күн бұрын

@@jonathanbott87 yeah dishwasher it was.

@CanizaM 14 күн бұрын

Very appropriate video for the 4th of July weekend.

@JVR2019 15 күн бұрын

Thanks for this video. I was wondering what was inside this exact type of device over my washer.

@davidbwa 14 күн бұрын

(not a plumber but worked on fluid systems) Here's a thought on why it is designed like that. Air slowly absorbs into water over time. So if you had the old time stand pipe like you talked about, I THINK that over time they can end up filling with water as the air trapped in them gets absorbed. The device you took apart is the same idea, but I'm thinking the plastic plunger / o rings / silicon grease serves as a barrier between the air and the water. Kind of like a really tiny version of the air pressurized rubber bladder tanks. Air can migrate into and out of water. I've had to deal with it in water systems for nuclear power plants and when I worked for a hydronic heating supply company.

@smoorej 15 күн бұрын

Sioux Chief mini arrestors work exactly as advertised, every time. Once I had to replace mine after many years of service but my local hardware store only had Chinese made junk which simply did nothing. I got new Sioux Chief ones and problem solved. Great product.

@polymath9372 14 күн бұрын

You didn't declare that you owned very large numbers of Sioux Chief shares! 🤣

@daveys 14 күн бұрын

I’ve used these before, but easiest thing is to just part close the inlet valve a little if there is one. Toilet cisterns can be prone to a bit of hammer. Used to see loads of issues after water tanks had their annual cleaning.

@erickleven1712 13 күн бұрын

Needed to add a pair of these to my washing machine. The water hammer through even 4' of rubber hose was enough to blow a crack into the Chinesium Brass valves. I kinda don't like having to shut down the whole house on a Saturday to go buy a valve, change it, and mop up the laundry room. These things are great.

@dilaliotube 14 күн бұрын

Similar to the baffle used in a Megaflo unvented cylinder. Used to maintain the air gap to allow for expansion of water in the store, as it gets heated. In a cold water supply pipe, I'd concur that the "Puck" is used to separate water from air and reduce the risk of legionella bacteria establishing a base camp.

@MacCaughey 12 күн бұрын

I can't speak for the UK, but the lower mains pressure in Ireland usually meant there was no need for these although, back in my plumbing days, I would occasionally find old inverted-Ts in the loft, just before the ballcock on the cold water storage tank. The 'modern' fix is a plastic paddle that clips to the float arm and dampens the bouncing of the float. Many years ago I got a call one Saturday evening for a house well outside my usual area. They had a deafening hammering from the loft and, on climbing up I could see that the paddle had broken and of course I didn't have a replacement. It took about 15 minutes to add a vertical, air-filled stub of pipe where the mains entered the ballcock. Silence and happy customers!

@OrlanDave 14 күн бұрын

Thanks for this video! I have been seeing these a lot at work (all I can say with my NDA), and I have been wondering what they are... now I know!

@jugularSignal 2 сағат бұрын

My parents have a pair of these on their washing machine. Cool to see the inside

@matthewholzinger1042 13 күн бұрын

The reason I heard about the old style was that over time, the water slowly erodes the air bubble away, which leaves no air buffer. Our US house was built in 1967. We have the inverted T style. We still had some occasional hammering, so we increased the length of one pair (hot and cold), and we have not had a problem since.

@SunriseLAW 3 күн бұрын

Recently replaced 12 y.o. tankless water heater due to some corrosion and a slight gas leak. It was installed w/o permit and did not meet code. Building code here in Eugene OR (and probably all over) REQUIRES the use of a thermal expansion tank on the cold water pipe going into the water heater, whether tankless or tank-style. It was a $40 part and is necessary because there is a check-valve at the water meters to prevent backflow into the water supply.