Water pipe has started "hammering" - how do I fix?

[ColoradoSkier]

Have started to get a water hammer when I run hot water through one of my faucets in my house. Seems to be isolated to one specific room. Any idea what causes it, or how I can fix it?

[denverd0n]

Shut off the water in the house. Find the lowest faucet in the house. Open it up. Find the highest faucet in the house. Open it also. Let all the water drain out of the system. Shut both faucets. Turn the water back on. Voila! The problem should be fixed.

If it is not then you need a new anti-hammer thingy (technical term :D ) in the pipe by the faucet that is hammering.

[JeepWheelin02]

I believe it is caused by air in the lines. Like said above, shut off the water to the house and you can actually open all the faucets in your house to drain the water out then turn the water back on to your house.

Im no plumber though but I did stay at the Holiday Inn Express last night.

[ColoradoSkier]

Will give this a try - thanks. I trust that this doesn't mean I need to drain the HW heater, even though the hammer is in the hot water line?

[denverd0n]

No, you don't have to drain the hot water heater.

It's not caused by air in the lines, it's actually caused by a LACK of air in the anti-hammer thingys. They soften the hammering by providing air space that can compress when the faucet is closed. Not sure how, but sometimes they get filled with water and then you have hammering. Draining the water from the system fills them all (there are usually several in the system) back up with air.

[Trango]

Water hammer is caused by abrupt cessation of flow, not of air in the lines. It is caused by a shockwave that travels back through uncompressable water away from the quick-closing diaphram or valve. Interestingly, the way to prevent this is to create space that the water can compress... and this means getting air in the lines. In plumbing, if you insert an inverted, capped pipe into the circuit (with air), you will give the shockwave something to push against.

They also make fancy springloaded things, but it's just as effective to have an inverted, capped tube.

If you don't have an arrestor of some sort, the shockwave travels through the plumbing, and hammers everything it touches - joints, valves, pipes, and any appliance connected. Ultimately, this can lead to component failure.

[JeepWheelin02]

Well there you have the correct explanation.

[satan]

while you're "draining"...

... since this is localized to a single faucet (if I'm reading the OP correctly), I would highly recommend inspecting the condition of the stem, seat and washer (or whatever type valve is used there on the hot-side). It's not terribly uncommon for a loose stem or floppy washer to oscillate -- the effect is essentially a high-speed cycling between flow rates through the valve that will cause the pipe to hammer.

I mean, since you'll be draining the system anyway ;)

[Sound_Man]

What you need is a thermal expansion tank on your hot water system. Many states/counties require it to be within code. I do not believe that it is required in Colorado but when I was in Fl it was. It will stop the "hammering" or rattling pipes.

http://www.watts.com/pro/divisions/watersafety_flowcontrol/learnabout/learnabout_thermexpansion.asp

[ColoradoSkier]

I'll start by draining the system and seeing if that fixes it. Starting to see some conflicting ideas in here.

[Steve]

What you need is a thermal expansion tank on your hot water system. Many states/counties require it to be within code. I do not believe that it is required in Colorado but when I was in Fl it was. It will stop the "hammering" or rattling pipes.

http://www.watts.com/pro/divisions/watersafety_flowcontrol/learnabout/learnabout_thermexpansion.asp

Dunno about CO, but it's code here.

[Sound_Man]

Dunno about CO, but it's code here.

When I replaced my water heater about a year ago in Fountain it was not necessary to pass code. Interesting...

[Hippie]

Skier - Did you drain the system before this started happening if not I doubt draining it now will fix it ( how would you get air in the system unless you drained it).

Most single family houses do NOT require a water hammer shock/expansion tank. It sounds to me like you had a pipe break loose from the strap holding it in place and everytime you turn on or off the water and the "shock" occurs of the water starting or stopping inside the pipe the loose pipe is vibrating and bouncing off the drywall, etc in the wall.

[ColoradoSkier]

Jeff - no, haven't done anything to the system for quite some time. Your thought seems more plausible since it is one pipe in one room - not system wide.

[Sound_Man]

I agree with Jeff. However if the retainers are in a wall you will be hard pressed to find and fix it. When I put a thermal tank on the water heater in Fl it was under $30 IIRC. Easy fix to stop the pipes from moving around.

[Steve]

When I put a thermal tank on the water heater in Fl it was under $30 IIRC. Easy fix to stop the pipes from moving around.

Yep. Home Depot and Lowe's sell them.

[Trango]

That may be the case, but pipes should not move at all, that's the whole point. Strapping down a pipe does not fix water hammer, it just removes one symptom of an overall, really bad disease, which can end in a flooded house.

[starbreaker666]

I have this same issue on our ranch style house. So opening the all the faucets after the water has been totally shut off can help?

[teamextreme]

When I replaced my water heater about a year ago in Fountain it was not necessary to pass code. Interesting...

Codes are based on the national code, but are enforced and determined on a county basis, so depending on the county it may or may not be required. I know my condo in Arapahoe county that was built around '97 has one, so I'm sure it must be a code requirement there. The builder is not going to install one unless he's required to.

[CapnCrunch]

I trust that this doesn't mean I need to drain the HW heater, even though the hammer is in the hot water line?

While you wouldn't need to drain the HW heater for this, if it's been a year or more since you last drained it, you should just take the opportunity to drain it now. This allows the built-up calcium in the tank to drain out and will help to maintain the life of the tank and the heating elements if electric.

HOWEVER...if it's been several years (or you have no idea how long it's been) since it was last drained, you may want to evaluate whether or not you drain it. The reason is that although draining regularly helps to prolong the life of the tank, if it's been a really long time since it's been drained you run the risk of the drain not being able to fully shut after you've drained it.

You make the call.

EDIT: Forgot to add...before you drain it, turn the water heater off, else you may burn-up the heating elements.

[Hippie]

Codes are based on the national code, but are enforced and determined on a county basis, so depending on the county it may or may not be required. I know my condo in Arapahoe county that was built around '97 has one, so I'm sure it must be a code requirement there. The builder is not going to install one unless he's required to.

Do you have hot water heat ? or is the entire building a shared water system ? if yes that means you are on a boiler which also has a recirculation pump that causes the hammer effect. Most city water systems are pressure regulated entering the house which remove the need for a shock - boiler systems and well water systems need the shock or expansion tank due to the additional pumps inside the house.

[Hippie]

I have this same issue on our ranch style house. So opening the all the faucets after the water has been totally shut off can help?

No

[Steve]

Do you have hot water heat ? or is the entire building a shared water system ? if yes that means you are on a boiler which also has a recirculation pump that causes the hammer effect. Most city water systems are pressure regulated entering the house which remove the need for a shock - boiler systems and well water systems need the shock or expansion tank due to the additional pumps inside the house.

Interesting. We do have hot water baseboard heat, but the boiler has its own surge tank seperate from the one on the potable hot water system.

[denverd0n]

I have this same issue on our ranch style house. So opening the all the faucets after the water has been totally shut off can help?
Yes, possibly, depending on what exactly is causing the problem. If you have some of the anti-hammer thingys (I still don't know their REAL name!), and they have gotten water in them, so that they are not softening the hammer anymore, then draining the system will put air back in them and make the problem go away. This has worked now for me twice. I'm guessing I have a problem with one of those anti-hammer thingys, but I only have to drain the system once every three years so that's a good enough band-aid for me.

If the problem is something else then this will not fix it.

On the other hand, draining the system is dead easy, takes very little time, and costs almost nothing, so you might as well try it.

[funon41s]

That may be the case, but pipes should not move at all, that's the whole point. Strapping down a pipe does not fix water hammer, it just removes one symptom of an overall, really bad disease, which can end in a flooded house.

x2

[Mkeeper19]

Have started to get a water hammer when I run hot water through one of my faucets in my house. Seems to be isolated to one specific room. Any idea what causes it, or how I can fix it?

I have the EXACT same thing in my kitchen... it drives me CRAZY!

[Hippie]

That may be the case, but pipes should not move at all, that's the whole point. Strapping down a pipe does not fix water hammer, it just removes one symptom of an overall, really bad disease, which can end in a flooded house.

Correct they should not move that is why they need to be secured to keep them from moving.

Water Hammer happens like you said earlier - ABRUPT CESSATION OF FLOW the vast majority of household systems do not have enough volume or pressure of water to create a problem ( I.E. bursting a pipe or joint and flooding)- that is why Water Hammer Arrestors are not required by code in most residential applications. Also, most of the valves used in a residential application do not ABRUPTLY stop the flow they slow it down prior to stopping it.

While I agree that an arrestor will cover the problem if the pipes are moving around in the wall eventually a joint will fail and cause flooding.


Here is a quote from the FAQs from this site (http://www.plumbingsupply.com/waterhammerarresters.html)



http://www.plumbingsupply.com/images/q.gif"Will water hammer arrestors stop all banging inside my wall? Will it solve my noisy pipes problems?"
http://www.plumbingsupply.com/images/a.gifThe water hammer arrestors will not compensate for poor strapping practices. If they are needed and work it is because faucets or valves can be closed too rapidly and create a water hammer. In other words, water hammer arrestors can solve some problems but not all. If you have both bad brakes and bald tires on a car then getting new tires won't solve all of your problems. Same with water hammer arrestors. They can't solve expansion and contraction issues or poor strapping issues but they certainly can usually help somewhat with water hammer issues.

In Skier's case this started abruptly, he lives in an area that by code did not require an arrestor when the house was built so chances of one being installed on the system now is about 0.0009%. More than likely a strap failled after ? years causing the pipe(s) to begin moving around banging against something.

[teamextreme]

Do you have hot water heat ? or is the entire building a shared water system ? if yes that means you are on a boiler which also has a recirculation pump that causes the hammer effect. Most city water systems are pressure regulated entering the house which remove the need for a shock - boiler systems and well water systems need the shock or expansion tank due to the additional pumps inside the house.
No hot water heat and no shared system. Standard forced air heat and gas hot water heater. Maybe what I have is not a water surge arrestor. It's a blue 8 to 10" diameter tank mounted (I think) off the cold water line entering the water heater (or maybe on the discharge side of the heater). I think I remember it having wording on it to the effect of "surge tank" though.

[Hippie]

No hot water heat and no shared system. Standard forced air heat and gas hot water heater. Maybe what I have is not a water surge arrestor. It's a blue 8 to 10" diameter tank mounted (I think) off the cold water line entering the water heater (or maybe on the discharge side of the heater). I think I remember it having wording on it to the effect of "surge tank" though.

Sounds like an expansion tank - not sure tho.

[CSP]

Interesting. We do have hot water baseboard heat, but the boiler has its own surge tank seperate from the one on the potable hot water system.

As it should. The water in a hot water system is isolated from domestic water as it can have anti-freeze additives (glycol) added to the water. That can't get into your drinking water.

I'm not sure how hot water heat entered the discussion, but any hot water heat system, unless it's very old and hasn't seen any service in the last twenty years, is going to have an expansion tank. This is because of the nature of a closed system and the natural expansion/contraction of the system as temperatures change.

It sounds like teamextreme does have an expansion tank. I've seen several with the wording "surge tank" on them.

[Steve]

As it should. The water in a hot water system is isolated from domestic water as it can have anti-freeze additives (glycol) added to the water. That can't get into your drinking water.

Never seen a house system with glycol or any additive but I 'spose it's possible. Ours is connected to the potable water system through a regulator to keep it full so it's not truly isolated, but there is no additive of any kind in it. We have an expansion/surge tank on both the boiler and the water line going into the water heater.

[CSP]

It is isolated in that there is a one-way valve between the hot water loop and the domestic supply.

In some locations the water is full of minerals or is corrosive. Those cases are examples of where glycol is used as/added to the liquid in the system. It is added to some systems also when a house is winterized and all of the water can't be removed from the hot water system.

A friend of mine specializes in hot water heat and I spend some weekends helping him with installs on big jobs, which are usually monster custom homes.

[teamextreme]

Sounds like an expansion tank - not sure tho.

Could be that. So how does an expansion tank differ from a surge tank (for minimizing water hammer)? Wouldn't it perform the same function by providing an air trap to absorb shock in the system.

[CSP]

Expansion/surge tanks have an air bladder inside of them which absorbs changes in pressure. At the end opposite of where it attaches to the water line there is probably a plastic cover screwed onto a shraeder valve just like the valve stem on a car tire.

People who are on well water also have one on a much larger scale which helps regulate the pressure in the house, keeps the well pump from starting/stopping as often, and keeps the well pump from deadheading when it's on, leading to premature failure.

This is probably similar in appearance to what you have teamextreme. Notice the nipple on the bottom. That's where the air valve is.
http://media.mydoitbest.com/imagerequest.aspx?sku=405264&size=2&warehouse=C&newsize=600

My house is on well water and the big one in this picture is what I have in the basement where the water enters the foundation. It has the same air valve on the top.
http://www.accentshopping.com/globals/images/vault/P/150818/normal/10033.gif

[Rando]

holy shit!! all this for some loose pipes. :D

all the service calls I've been on for "water hammer" are almost always just loose pipes banging around when as mentioned above there's a sudden cessation of flowing water. usually on a solenoid controlled fixture like a dishwasher or washing machine or ice maker. a faucet turned off really fast can cause it too.
just get under the house if possible or put your ear against the wall and have some one turn the valve off to cause the noise. secure the line and thats it.
check your water pressure too. if the reg is out to much pressure will make the problem worse.
installing a water hammer arrester is a big waste of time and money in a residential system.
the only time they are required is on a solenoid controlled application in my opinion.
putting the extra piece of pipe in the vertical with a cap on the end doesn't really work either. the water absorbs the air pretty quickly since it's under pressure and then it's just a dead end filled with water.
there's more to a water hammer arrestor than just a dead air space.


just noticed this,

Could be that. So how does an expansion tank differ from a surge tank (for minimizing water hammer)? Wouldn't it perform the same function by providing an air trap to absorb shock in the system.


two differences.
a surge tank ( I've never seen one for a domestic water system anyways) wouldn't work. water hammer happens at the end of a water line branch.
thats also why an expansion tank won't work either.
the arrestor needs to be at the end of the line not in the middle. plus the rubber bladder in the expansion tank isn't really designed to absorb shock. it expands and contracts slowly to accommodate hot water expansion.