Banging Zone Valves

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Banging Zone Valves

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khalaired

I have this exact problem with a 2 zone valve installation where if any valve closes either on its own or when the other valve is open or shut there will be a loud bang where pipes will hit each other and there will be some sort of water hammer. Any suggestions?

hot_rod

Check the flow direction, there should be a flow arrow on the valve.

Generally valves bang when they are trying to close against excessive pressure. It could be the circulator pump is oversized.

newagedawn

do you have pics of the boiler and piping, id bet its the piping, do you have 3 zones on a 1 " pipie?

DanHolohan

Who made the valve?

Steve Thompson (Taco)

Assuming this is a new problem and the system ran ok for years, what happened prior to the noise starting? Any service work done?

Big Ed_4

Normaly you want to zone valve furthest away from the circulator . If its an spring loaded like an Honeywell ,you can try disconecting one of the springs to slow the shut down

weatherman

I have been in the HVAC business for many years and never had that problem
We always installed valves in the return side (Taco)
I prefer valves to circulators in that I could instruct our customers how to change the valve by phone saving them s service call
I'm just saying!

pitman44

We have run across this problem many times over the years. Our usual fix is to replace the fast closing valves (Honeywell, Erie) with slow closing valves (Taco). And like Weatherman we too always use Taco valves.

DanHolohan

Yes

fastd

I had a Honeywell zone valve on my system that gave me trouble a couple of times, though never had this problem, happily enough. Changed it to a Taco a few years ago and no problems since. It's on the supply side of the system. I like that electronic device idea to solve the problem of the banging. Too bad nobody picked it up.

ChasMan

If it is a Honeywell, slip off one of the return springs, that helped mine a lot and it is a reversible mod.

HomerJSmith

I'm with 'hot rod' on this issue. I had the same problem on a system. The Honeywell zone valve was a long distance from the boiler and the installer mis-identified the supply and return piping and tried to correct the problem with an expansion tank, supposedly using it as a shock absorber, to no avail. I switched the valve direction and removed the tank. Walla!

Removing the spring, especially on the supply side valves, can lead to incomplete shut off and bleed thru. These valves are designed to shut off against the flow. There is a point where pump pressure will push thru these valves. In that case use a Taco Sentry Zone Valve.

Had a case where Honeywell zone valves allowed push thru and replaced them with Caleffi zone valves and that solved the problem.

ChasMan

If you remove the little one, it won't affect the shut off clamping force, they probably designed it to shut off on big pumps. On a 007, you do not need that much force to shut it off. If the piping is long, and has a lot of water in it, it has a bit of momentum to it. There is no sign of it bouncing when it closes, it just closes, 1 spring or two. Cheap easy homeowner fix. If it doesn't work, hook it back up. No harm no foul. Or, you could move it around, cut pipe and solder half the day hoping it might fix it.

hot_rod

When you watch that valve close with a slow motion video you will see it bounce 3 or 4 times. Usually only when it is closing against a high flow velocity.

The best fix would be confirm the circulator is sized correctly.
Or a pressure bypass valve or delta P circulator.

Removing a spring will change the close off pressure. Zone valves are available with higher close off pressure for jobs with high flow velocity; high delta P in the systems.

Air handlers generally include a low Cv high shut off valve as they are often installed in systems with large circulators in multi zoned systems like hotels, etc. Lower Cv (smaller opening) higher shut off delta P.

Properly sized and installed no zone valve should bounce or need field modifications

ChasMan

I have delta P circs and Zone valves on the return which are properly oriented and I can still get a bang now and again. So, what's not designed correctly? When all five zones are open, and one particular zone closes, I get a slight bang out of it. That zone has a lot of pipe, about 200 feet. It really banged loud with the Honeywell. Removing one spring fixed it. Fixing the Z One was not as easy, I had to take a couple of winds out of the spring, quiet as a mouse.

HomerJSmith

3/4" pipe @ 200' @ 2 gpm is a lot of stored momentum. By removing the spring you are making the valve a slow motion shut off slowing the momentum, reducing the water hammer. Remember flow is the same in all parts of the circuit. You could still have bleed thru.

What would happen if you soldered in a washing machine water hammer arrester before the zone valve, at least 1 ft away? Hmmm!

hot_rod

2 gpm in a 3/4" pipe is a bit less that 2 fps, that should not be an issue for any ZV to close off against. Usually velocity well above 4 fps is where sudden stopping of the fluid is a concern.

I've never heard the momentum theory? 200' of 3/4 pipe isn't all that much volume. If that theory was possible what about cast iron rads piped with 3/4 ? I think it is fluid speed more so than volume.

With 5 zones open and a properly adjusted and working ∆P circulator it should not be an issue either.
What mode are you running the ∆P circ in? Did you try it in all 3 modes?

If it only happens with that one zone with 4 or 5 others flowing I'd suspect a loose pipe somewhere?

HomerJSmith

'hot rod' that's what momentum is "speed plus mass". You can adjust either one to achieve the same result. Lottsa mass at low velocity = low mass at high velocity = same result. You can store energy in mass.

The Universe seeks equilibrium, that's the theory of entropy. Sooner of later, equilibrium is achieved and the lights go out, speaking of the Universe. Man expends energy to create disequilibrium and uses that Law to create work. Think of a battery. Man's energy goes into it to transfer that energy in another place or time. The battery's energy isn't free it was stored by the energy man put into it, earlier.

That's what a pump does, creates disequilibrium that moves mass that is stored with heat energy. This is what you alluded to when you suggested that maybe the pump was sized too big, creating a more energetic flow.

hot_rod

Be that as it may,

In this drawing what is the pressure at the two points 10 feet below the water level?

Would it not require the same force to close off flow in either?

HomerJSmith

The static pressure is the same in psi.

"Would it not require the same force to close off flow in either?" I would say yes.

There is a difference between static pressure and dynamic pressure.

hot_rod

What about this drawing, same static, same dynamic, same amount of force required to shut down?


I think you may be thinking more about area in regards to shut off pressure.

Here are 3 zone valves,
1 Cv, 2.5, 7.5 in a 3/4 and 1-14 size

The 1 Cv can shut off against 75psi ∆P,
the two on the right 7.5 Cv only 20 psi ∆P, regardless of tube size of the body.
Due to the larger orifice the shut off is lower in the higher Cv valve.

The point is, it's not about how much volume, mass, weight is above the valve.

A zone valve rated for the shut off should be able to close off ∆P regardless of the length of the circuit or volume of the fluid in the piping.

HomerJSmith

There is kind of a fallacy in your drawing when I think about it because it wasn't stated that the levels of the ocean and tube were the same. I assume they are. It looked like they were.

Static pressure is the weight of the mass pressing down as a result of gravity's pull on matter. The level of the ocean and the top of the fluid in the tube must be equal. Any variation would lead to a difference in psi. That's my thinking.

ChasMan

I don't think it is a static dynamic thing since that has to do with velocity vs area and not mass. It's one of those things I can not explain exactly. The only difference between my hammering zone and the ones that do not is the length of pipe and the fact it has a vertical component. It is my second floor zone. The behavior is consistent. I can make the third floor bang like bejeezus in my triplex but the first and second floor zones are ok.All I know for sure is that the Honeywell closes way too fast, The Caleffi should close about 20% slower and a differential bypass is on my list next time I put in a new boiler which might be sooner than later but opening up all this pipe to put in a bypass seems like too much work for the size of the problem. Not just the work, It is an unplanned add and will look like spaghetti in my case. As for tying pipes down, you can't really do that. Mine are all in hangers mostly except where they go upstairs. I have not opened the walls to look but my guess is they put a piece of 1/2 inch pipe between the 2x4's and soldered the riser together to support it. That may very well be the source of the bang.

HomerJSmith

'hot rod', were off topic. I'm talking about momentum, not just about volume. The water mass of a 200' circuit is greater than the water mass of a 1' circuit, I think you would agree. Mass in motion has force, the ability to do work.

A rain drop hitting your car at 60 mph does less damage than an 18 wheeler hitting your car at 60 mph. The crushed metal is the work that momentum created.

A Honeywell zone valve closes against the flow. When it is installed backward the ball closes with the flow and the spring energy is added to the momentum of the water and a sudden decisive water hammer occurs. The Honeywell zone valve closes slowly and more slowly against a flow. The momentum of the water causes the ball to bounce several time as you stated before shutting the flow completely. It is the spring energy that balances out the flow energy and overcomes the flow energy for a complete shut off. By removing a spring, you lessen the spring energy and the valve closes more slowly against the flow allowing the flow energy more time to dissipate. But...the remaining spring energy must be sufficient enough to overcome the flow force to close the valve.

My only concern is if the spring energy can't overcome the flow force and a bleed thru happens. It's not the end of the world and probably no one would notice. It is a solution that satisfies the annoyance without solving the cause of the problem.

HomerJSmith

Chasman, It is not area, it's mass. These are two different things. Static pressure in a closed system is irrelevant. It is a dynamic pressure thing. The pump creates dynamic pressure.

There are some good suggestion here, just needs follow up.

ChasMan

Yeah, but none of the formulas for calculating dynamic pressure include mass as a component. The momentum, changes the force which is not the same as pressure. Related for sure though. Anyhow, I know if you remove the actuator from a caleffi valve, it ain't opening for anyone without a pair of vice grips. So the spring holding it closed theory doesn't wash with me
On the Honeywell one though, I don't recall any issues doing it but I have not used a Honeywell for a long time. I am not one to trust engineering from commercial enterprises so much. A lot of this stuff is underdeveloped in one way or another. My latest pet peeve is with Tacos ZVC Boxes. They have a red hot resistor limiting current to the power LED. No excuse for that except lazy engineering and non-existant or ineffectual QA
.

hot_rod

Here is what I'm questioning, you suggested:

3/4" pipe @ 200' @ 2 gpm is a lot of stored momentum. By removing the spring you are making the valve a slow motion shut off slowing the momentum, reducing the water hammer.

A 2 gpm flow in a 3/4 tube, the water is barely moving, under 2 fps, very easily stopped.

I'm suggestion there could be thousands, maybe hundred of thousand HW and other brands of spring return ZV closing off against the circuit you suggested without any noise or water hammer problems. Spring return ZV are by far the most common, built by a dozen or more companies, millions installed world wide.

Valves bang when they are trying to close against high velocity or excessive ∆P. That is why valves are offered in different shut off pressures.

Radiant manifolds have much more tube length and spring return ZV close them off without banging.

I suggest something else is going on like possible inadequate pipe support in the circuit. Maybe more like a whiplash effect with unsupported pipe?

The cause of the valve bounce we observed in the slo-mo video is the spring tension loading into the motor, it becomes a mini flywheel. Once that energy dissipates by bouncing the ball several times the valve will seat. Think of an old lawn mower engine with a heavy cast iron flywheel, compared to a chainsaw motor.

You can also observe this by removing the thin metal cover on the motor. The motor will stop, reverse, bounce back and forth several times before coming to a complete stop. The hammer is created by that bounce, high velocity makes it worse, but that is not the case with Chas, as far as I can tell.

There is a reason for the dual springs on the HW, I doubt the intension was to remove one to fine tune the valve Removing one is treating a symptom, not the cause of the problem.

Springs have a profile not unlike a pump curve. The challenge with a pull back spring like some valve use is a lot of pull back when fully extended, not much at the closed, near relaxed position. Think of how a screen door slams when fully open compared to partially open.

Some ZV brands use a coil type spring which has more wraps and the tension is much more equal from wide open to completely closed. More like a flat curve pump as an analogy. In addition a lost motion gear disconnects the spring from the motor so you eliminate the flywheel potential effect when power drops off.

ChasMan

As anecdotal as my evidence is, I would hazard to guess that there are a lot of hammering valves out there. Judging by the big box store shelves, the wax actuator valves are by far the most popular. The close slow. I just could never get over the power draw and the pulsing It feels like pre war engineering. I had high hopes for the electronic ones. They were super slow closing but proved in reliable. You asked what speed I had the pump set at. I put it on the slowest speed unless it gets real cold then I flick it up to high. It hammers about the same. It is rare though because Iyt will only do it when other zones are running and I don't have the heat on in that zone most of the tie anyways. There is some water velocity wooshing noise that preceded the bang too. As you might remember, I am on a mission to get rid of my flowchecks. That may help as well.

hot_rod

ChasMan, you mentioned you have a ∆P circulator, have you tried it in AutoAdapt or one of the ∆P modes. Although if it bangs when other zones are still open it should not be an excessive velocity issue.

The flow checks could be the cause of the noise?

It really doesn't matter the height of the building, spring return valves are used in high rise all the time. The Z-one has a 300 psi pressure rating and close off up to 75 psi ∆. That should cover a very wide range of installations.

We do a lot of flow testing on valves and have taken that valve well beyond the listed numbers both for leak by and close off. Properly applied it is a 100% bubble-tight seal.
We sell boatloads of these valves to OEM fan coil manufacturers as they tell us they outperform other common brands.

I know the Caleffi Z-one takes 10 seconds to close fully. While not a slow close per say, much slower than solenoid type zone valves.


Here are some pics of what is under the hood.

HomerJSmith

Interesting. 'hot rod' says, "The hammer is created by that bounce, high velocity makes it worse..." I would want to see proof of that. My thinking is that water (mass) and flow (velocity) is energetic (force). When the water is suddenly stopped the energy has to go someplace (dissipate). That stored energy stored in water does shake the pipe and will slam against the the pipe along the length of the pipe as water is basically incompressible. I'm thinking of a washing machine solenoid shutoff valve. There is no bouncing there that I'm aware off and water hammer arrestors work very well in adsorbing the flow energy. My contention is that flow is suddenly stopped that energy is converted into vibration of the pipe which makes the sound. In the case where a Honeywell zone valve is installed backwards, the flow shuts the valve off rather quickly and there isn't any bounce because of the springs and flow forces the ball to the closed position, but the noise is still there.

I think I would install a water hammer arrestor near the valve and take things from there.

There is the possibility that there is a swing check or such in the circuit somewhere that's slamming shut and that's making the noise. Sound travels very well thru dense material like pipes and water.

By the way, Caleffi makes a hell'va good valve and it isn't much more expensive than a Honeywell valve.

hot_rod

Homer, I'm not disagreeing with your energy in motion comments. In fact I have researched elastic or hydraulic shock in regards to intermittent back flow preventer spits. Fast closing valves like commercial dishwasher solenoids, wash machine solenoids, in some cases flushometers can create a shock that carries thru the piping. High flow rates and high pressure domestic water applications. 80 psi systems can jump to 120psi or more, then drop below the incoming pressure. Looks like a AC current wave on paper, see below.

The expansion tank does also absorb some of the fast close impact, should not need hammer arrestors on hydronics.

My point is I don't think in the 200' loop at the flows suggested in this case would/ should cause a hammer with any of the spring return zone valve. One spring or two Low flow and low ∆P from the circulator mentioned, in addition to other zones open.

Certainly ZVs installed backwards all bets are off.

Solid_Fuel_Man

I have installed many Z-one zv's and habe yet to have one bang. I'm with @hot rod you have excessive velocity.

I do understand what you are saying about a long pipe run and that momentum having force etc. However, with 2gpm that momentum is very small, turn the Alpha down and see what happens.

HomerJSmith

Look, velocity doesn't cause water hammer. Velocity is nothing more than distance over time, like speed or what we call flow rate. We can measure it in mph or ft/sec, but you are measuring something real in motion. Velocity is one way to describe what is happening to something that's real, solid, matter, or mass (property of a physical body), in this case water. It is the mass that causes water hammer. It is the velocity of that mass that does the work (vibration=sound).

Solid_Fuel_Man, when you say velocity what you mean is the velocity of water. We assumed that, and you're right. It might be the cause of the water hammer. The way to deal with that as has been posted on this thread, is a delta pump. I might add two more: a balancing valve limiting the flow rate and re-piping with larger diameter pipes which would reduce the flow rate (not practical, but a solution , none the less).

The other suggestions deal, not with velocity of water, but with the effect of the velocity of water, which I call the momentum of water (force) and that is: remove a spring in the zone valve or install a slower acting zone valve, which deals with the "time" element of velocity. A gradually closing zone valve slows the flow rate and allows the flow energy to dissipate over a longer time frame, that will work. My only concern was that removing a spring might result in bleed thru (incomplete closing of the ZV with a continuing flow thru the circuit, albeit, at a much slower rate). The spring force must over come the flow force to have a complete closing of the ZV because the ball is pushing against the flow. You have force pushing against a force. The greater force will overcome the lesser force.

A slower closing valve, by design, with complete shut-off would be the better choice. I suggested a water hammer arrestor to absorb the flow energy when the valve closes. I have never used one in a hydronic circuit nor have I ever seen one use in that manner, but I think it would work.

There is a dearth of information by the persons who post as to the problem that they have and assumptions are made that the problem is accurately described which may not be the case. That is why you'all, repeatedly, ask for pictures.

Nuff of this, stick a fork in me, I'm done.

zipper123

My husband and I just did a conversion from
Oil to gas so everything is brand new including the boiler and hot water heater. It’s been about 2 months and all
We have us problems. First we had leaking that took about 6 weeks for them to find the problem now the next problem is that there always seems to be air in the system no matter how much they purge the system. On one of Honeywell valves there is this knocking sound everyone the boiler turns on and especially when the hot water is used. It almost sounds like a boiling noise. They changed the valve thinking there was a defect in it but it’s still happening in the new valve. It’s very loud and annoying. It sounds like the problems that are listed above. I’mGoing to ask the plumbers to change it out for a taco valve hoping it won’t make any more noises but can you mix and match Honeywell and taco because we have 2 other valve zones that are honey well I have a video of the noises but I can’t seem to figure out how to upload it

Solid_Fuel_Man

Some pictures would help if you cant get the video.

zipper123

Solid fuel man....Here is a link I believe u can see a video
https://share.icloud.com/photos/08x5owj_rnQ634KBI1N0c_EOg

DanHolohan

Regarding the Honeywell valves. This should help:
https://heatinghelp.com/systems-help-center/banging-zone-valves/

zipper123

https://share.icloud.com/photos/08x5owj_rnQ634KBI1N0c_EOg

Jamie Hall

Actually, without getting too enmeshed in the physics or it, there are two sources of water hammer with a fast closing valve (if you think you have problems, try a 4 foot diameter aqueduct, 6 miles long...). The first -- and much the more obvious, is the flow velocity acting on the valve, whether it's a flapper or a plunger doesn't matter. That velocity increases as the valve starts to close, grabs the valve element and slams it against the seat. This stops the flow, of course -- the energy in the flow is taken up by expansion in the pipe itself (and a little in compressing the fluid) which sends a pressure wave back up the pipe. Which action, if it is enough, can lift the valve back off the seat... then the returning pressure wave from the other end cause it to bang down again... and so on. The other is much less obvious: closing the valve will cause a reduced pressure on the downstream side. If this reduced pressure is low enough, you can get cavitation there, and a returning positive pressure wave from somewhere downstream, which lifts the valve briefly, which then closes with a bang. Rinse and repeat.

There is quite an extensive literature on water hammer related to valve closing, but almost all of it has to do with much larger applications -- water supply systems and hydroelectric power -- where the problems can be far more destructive than just a noise. Most of it, also, is old -- much of the research was done in the late 1800s. But that doesn't make it of less value.. The ultimate answer in those applications both then and now was and is to either provide slow closing valves (always manually controlled or powered open/powered shut), nearby (very near by) standpipes to absorb the pressure waves, or bypasses which took the water flow if a rapid change was needed, which could then be closed slowly (mostly for hydroelectric work, where a near instantaneous change in flow is sometimes required).

Troubleshooter

What a brilliant article! Thanks a lot for your sense of humor too, you gotta right some short stories.
I'm long time an elevator trouble shooter. Last year replaced my Electrozone boiler (installed 1969 with 20VDC solenoid zone valves) with Weil McLain and Honeywell valves and right away had this banging problem only on the top (fourth) zone. It's funny but as I can see this problem chooses only bedrooms so we had the same scenario. Due to the highest zone the air was my first thought and even having Spirovent on the boiler I made an air bleeder on the highest pipe. No success. I was also puzzled why it didn't happen all the time.THANKS A LOT, it's quiet now after one spring was removed but it's not a big deal to come up with new circuit stopping the pump when valve closing and then restart it again, I just don't need it..