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Tanklets > Strange Noises

Q: There is a very strange noise coming from my hot water heater. When I sit in the kitchen, it sounds like I am in the belly of a Spanish galleon on the open sea! What on earth does this mean?

A: Hello: Get a pressure gauge and watch it as the unit makes noise. I'll bet it's a result of very high pressure. You likely need a working relief valve and possibly an expansion tank. -- Larry (12/4/10)

Q: Hello again everyone. I replaced our natural gas water heater about two years ago and have recently started to have an issue, and doing some searching here I have a new idea and want to see what y'all the experts think before spending $$ and wasting my time.

Basically we have a rattling hot water line, that shakes and rattles violently right at the water heater. This used to happen once in a blue moon with the dishwasher, but now it happens every time we run the dishwasher and also when we run the washing machine (not necessarily at the same time). Just turning on the dishwasher will cause the noise at some point in its cycle, and turning on the kitchen faucet when the dishwasher runs is guaranteed to make it happen. Shutting off the faucet or stopping the dishwasher/washing machine will instantly stop the rattling.

I can grab the hot water pipe where it goes into the wall and move it from the drywall cutout, but it still shakes in my hand and I can't stop it. Now what i have done. First I tried to turn down the heat on the water heater. Didn't help. I have it set almost all the way down, it is in the "WARM" section of the thermostat. Then I shut off the water at the street and starting at the back of the house opened every faucet/toilet inside and out and turned on the washing and dishwasher to get all the air out. No help at all. Last night I went and bought one of those cheap little water hammer arrester but have not installed it yet because I don't feel like this is really water hammer.

So now I read on here about those little check valves. Yes, I have one of the silver check valves installed on the hot water side of the heater. Not sure if there is one on the cold side, but I know I also have a ball-valve on the cold inlet side that I keep wide open (replaced this heater twice because of a "flammable vapor" safety device inside that blew out last time I cut drywall in within 6 feet of the heater and wanted a faster way in case it happened again). Could this check valve be my issue? I seem to remember when I installed it, it looked like simply a cheep piece of plastic inside the nipple.

I'd love to simply need to replace that nipple and not have to install an ugly air chamber since we are about to sell the house and I also don't want to cut into the wall to hide it in there. Sorry for the long post, but I think I listed everything out and hoping someone will shed some light on this annoying and noisy problem.

A: It's most likely the heat trap nipple causing the noise. Replace the nipple with a regular nipple. -- Undee70ss

Q1: Thanks for the reply. I just got through replacing the nipple with one that is just plastic lined, both the hot and cold side. Still getting the noise, actually it is worse now. Before I would only get it on the kitchen faucet when the dishwasher was also running, now I get it as soon as I turn the hot water on.

A1: Hello: It would be nice to have a description of whatever the water flows through to get to the dish washer and washing machine. Softener, check valves, filter, pressure reducer...? What does the water see? Also, what is the static water pressure? It might be WAY too high. Do you only get noise using hot water? Is there water hammer? Do other hot water fixtures ever get noise? The more we know about the system, the more likely we'll be able to tell you something intelligent sounding. -- Larry

Q2: Larry, I'll answer all of those questions because they ended up being very relevant, but I solved the problem last night. Hopefully by putting all this info down someone in the future can read this thread and solve their own problem, saving a lot of time and money.

The house is old, and the kitchen faucet and dishwasher flow off of the same shutoff valve in the kitchen. I checked the water pressure and it wasn't too high, I check it a couple of times a year and it is always around the same number. With an old house and large trees I check it to make sure I'm not leaking under the house somewhere.

Yes, I only got the noise when using hot water, and only on the kitchen faucet or the dishwasher. The washing machine would also cause it, but more on that in a minute. I've never had water hammer, just the shaking and clanging of pipes. No other fixture in the house EVER made the noise. So that last line should have keyed me. When working on an engine, if I hear a tapping I'm not going to tear down the transmission, but that is basically what I did here.

I ended up replacing both of the check valve nipples on the heater, then draining the whole system. The sound got much quieter, less banging and more of a humming/vibrating sound. So I thought I was on the right track. I let the noise go and traced it through the wall, under cabinets and decided to start right at the source that i could get to, the shutoff valve under the sink. I decided to turn that off, and noticed that when I did it only went about 1/4 turn to complete shutoff. That was odd, so I immediately turned it back on. The faucet started to shake, and then as I turned it more on the noise completely stopped.

The ENTIRE PROBLEM WAS A PARTIALLY CLOSED VALVE. Two seconds to fix. The noise and rattling I was hearing was because the faucet and dishwasher were starving for water, and trying to basically suck water through a restricted valve. The washing machine, thinking about it only made the noise when the kitchen faucet was then turned on, never made the noise on its own.

So I got good practice in replacing the nipples on the water heater, but could have fixed it with a simple twist open of the shutoff valve under the sink. I guess it might have been bumped when cleaning out under the sink and nudged just enough to start it making the noise. But, it is fixed. That is the important part. Thanks to all who read this and gave it any thought.

A2: Hello: Thanks for the detail. Along those lines, it happens sometimes that with the old-style valve stems that have flat washers, the screw holding the washer works loose. This allows the washer to "flap in the fluid breeze" under the right flow conditions. Drives people loony. Simply tightening a screw eliminates the noise. -- Larry (8/11/10)

Q: Our water heater made such a loud squealing noise that it woke up the whole family. We also have a water softener system that recycled at the same time (twice weekly). I'm not sure if this had something to do with the noise since this was the first time we heard this sound. It lasted about 3 minutes. We have a 50 gallon tank that was in the house when we purchased it last year. I have no idea how old it it. We haven't had any other problems.

A: Sound travels much faster through water and metal than it does through air. I've heard similar loud squealing sounds, but they came from pressure regulators that were having water leak backwards through them due to thermal expansion. Do you have high water pressure and a pressure reducer? If so, do you have an expansion tank? That might help prevent the high pressure that ultimately causes the noise you describe.-- Larry (12/11/06)

Q: I have a 9 year old Bradford White electric water heater. I have been using this same heater since it was installed when house was built. After returning home from a vacation of 10 days I have started to experience a continuing water hammer type noise at the inlet gate valve of the heater (I think).

I have regularly drained sediment from the heater monthly since it was new. This noise only seems to occur after one or more shower is taken. Once it starts it does not stop unless I turn off the water supply to the tank and then reopen the valve. Then no noise!?! Using the clothing washer does not cause the noise. Water pressure at all outlets appears unchanged.

In my past experiences with any water hammer noises they were always a single sharp sound, no repetition (in another house). This does not seem as strong or loud but keeps knocking until water is turned off. I have turned off the house supply and drained all the valves and have also operated the tank pressure relief valve. Noise persists. There are no leaks in the system. Do you think a "Water Hammer Arrestor" is the way to solve this? Any help is appreciated.

A: The possible culprits: Heat trap, check valve, pressure reducer. I've had all three cause this sort of trouble. From your description, I'd place heat trap as the "most wanted". Quiet heat traps are made now. It would be nice to know what the water pressure is too.-- Larry

Q1: I have checked the installation and can find no heat traps, pressure reducers on check valves installed. Strictly a valve in the line of the water supply. Would adding heat traps cure this condition?

A1: Try turning the gas control down when you hear the noise. If once the flame (and thermal expansion) stop, the noise stops, then it is a clue that something may be restricting back flow. Is there a hot water recirc line with a check valve in it? What you describe is the sound of a mechanical part. We need to find out where that part is..-- Larry

Q2: It is electric. I suspect the inlet ball valve is causing this noise problem. I drained the house pipes again and left all faucets open, flushed toilets and opened heater pressure relief valve. I also made sure the inlet valve to the tank was fully open. Let the system stand for a few minutes then closed everything back up and opened main water valve. After all pipes were bled for air, next two showers had no hammer effect. My thought is the valve may have been slightly closed and caused the water hammer effects. I will monitor this but I am now fairly sure the trouble is in the pipes and not the water heater. (6/27/06)

Q: Lots of great information on this site, perhaps someone can help me out... Recently purchased a house, has new electric water heaters in it (less than a year old, but more than 6 months). There is a 40-gal one for just the master bathroom in the ceilng. Works great, haven't had a problem so far...

Last night we heard a pop/crack/bang type sound. Not too loud. Sounded metallic. Too sharp to be duct work. Didn't sound like wood settling. Didn't give it much thought. A little while later same sound, twice in quick succession, maybe a little louder. Within half an hour same sound, much louder. Time to investigate... Was up and around trying to figure it out when we heard three extremely loud and sharp bangs in quick succession. As if a very impatient person rapped very hard on a large doorknocker. Became suspicous that it was coming from where the water heater is.

I opened up the taps in the bathroom. Hot water came out, not at all scalding, but perhaps hotter than usual. Checked outside where the relief valve pipe exits the house and it was bone dry. After letting water run awhile, closed taps heard heater refilling. Didn't here anything else all night. Just prior to the whole incident two showers were taken which would have probably used up most of the water in the tank.

So.... Any brilliant ideas? Haven't been able to repeat the condition. Evidence it is the water heater a bit circumstantial, but enough to make me worry about the thing leveling the whole house. Thanks in advance for anyone's wisdom!

A: Do you have a check valve, back flow preventer, pressure reducer or anything else in line that may get in the way of thermal expansion? Try using a lot of hot water again and then putting a pressure gauge on the heater's drain valve. If pressure rises, there is a problem you need to find. High water pressure won't level the house, but will break the heater or some other plumbing. You may want to test the relief valve too (and be prepaired to replace it)! -- Larry (4/08/05)