Thumping noise in home

[Gordon Shumway]

I agree with your diagnosis with one minor exception. Not only could it be the hot water supply lines expanding due to the heat, but it could also be the drain line for the same reason.

[Dom]

Thanks to everyone again. I'm really interested in that mechanics stethoscope deal. Do most plumbers have that? Or do I have to call someone special?

[nestork]

No, most plumbers wouldn't even know what it is.

Just look up "Tools" in your yellow pages, and phone the places that sell automotive tools. All of them will know what a mechanic's stethoscope is and will probably either carry them or will be able to order them for you.

Don't pay more than $20 for one because even the cheap ones work well.

Also, there are electronic mechanic's stethoscopes that have a LED read out that tells you when you're pointing it at something loud. I don't know how these this work, or even if they work, but the cheap ones you put on your ears have been a benefit to me in pinpointing all kinds of noises, from washing machines to furnaces to electric motors to the engine in my car.

Our hearing is simply not precise enough to pinpoint the souce of a noise by hearing alone. A mechanic's stethoscope allows you to pinpoint the source of a noise because it has a metal diaphragm that reproduces the noise in the ear phones you're wearing. When the metal probe is touched to the source of the noise, that diaphragm moves the most, making the noise you're trying to find sound the loudest in the mechanic's stethoscope.

So, in practice, you would go into your crawl space and touch the probe to any of the pipes you suspect of making that noise. The pipe that sounds the loudest is the pipe making the noise. Then you would move the probe of the stethoscope along the pipe until the noise you're hearing is the loudest, and that's where the pipe is rubbing on something, and the rubbing movement of the pipe is causing the noise you're hearing.

Or, at least, that's what I suspect is causing the noise, and that's how I'd go about finding the source of the noise and correcting the problem.

[RobertMacy]

Here in Arizona the well water is known for hardness, not as bad as being able to stand a spoon up in a glass, but so bad that when any water driess it leaves a chalky white sheet over the area. With our electric water heater the bottom element makes a LOT of those little 'rings' that fall off [sometimes] and accumulate in the bottom, or simply leaves a huge quantity of sludge right up to smothering that bottom element. We're talking REPLACE the bottom element because it becomes coated with a sheet of solid scale and thus burns out any where from 6 months to 12 months. Living here for 4 years, we've gone through six elements. HOWEVER, I have avoided replacing the whole heater tank when I discovered a simple technique.

I had a bottle of cheap muriatic acid from HD, about $5 a gallon. Everytime I have the bottom element out, and the tank is almost drained I use a funnel and pour some into the tank through that bottom access. Major sizzling sounds insue, I let it sizzle until subsides, then slightly fill the tank and drain again [plug the hole though] repeat until I hear no sizzling sound. sometimes twice sometimes three times. Then completely fill and flush, put in the new element and the whole heater now is going about 16 months between element changes! In another home I used to shovel out sludge, but that is riskly for damaging the tank liner. So far, I've headed off a complete hot water heater replacement, had great quantites of hot water, so happy.

Faced with the choice replacing the hot water heater [costly] to trying to flush the tank at a cost of about 1/4 gal of muriatic acid valued at $1.25 which may, or may not, bring back the tank, you might consider trying it.

[nestork]

Robert:

Since this is an electric water heater, any scale that collects on the bottom of the heater is scale that has fallen off of the heating elements. Those pieces of scale won't be sticking to the bottom of the water heater tank or grow in size like the scale will on a gas fired water heater. They probably won't even be sticking to themselves.

Why not try using a couple of plastic pipes connected to each other with either a 45 or 90 degree elbow and a wet/dry vaccuum cleaner to vaccuum the water and scale out of the bottom of your tank.

Each time the vaccuum cleaner sucks the water out the bottom of the tank, remove the motor from the base of the vaccuum cleaner, pour the water into a pail and shovel the scale out of the bottom of the vaccuum cleaner base. Then, pour the water back into the tank with your funnel and the plastic pipe assembly, and vaccuum the water out of the heater again. Each time you do that, you should remove more and more of the scale from the bottom of the tank. Note that you don't need to remove all of the scale from the tank, but enough to make sure that the scale is well below the elevation of the bottom heating element in the tank.

It would take some trial and error testing to find out how large a pipe and 90 degree elbow you can get into the tank through the opening for the bottom element. Once you know how large an elbow can be made to fit through that opening, it would take more testing to determine how long the section of pipe inside the tank needs to be to reach to the bottom of the tank, but that would simply be a matter of cutting that section of pipe shorter each time until the end of the pipe is maybe only an inch off the bottom of the tank.

Or, at least, for the small cost of a couple pieces of plastic pipe and an elbow, and some makeshift way of connecting that plastic pipe assembly to a wet/dry vaccuum cleaner, I'd be inclined to give that a try.

Even if it didn't work to remove the scale, you could use that plastic pipe assembly to vaccuum the spent muriatic acid out of your tank in the procedure you're using now.

[TomR]

I think the later posts about scale in the hot water heater being part of the problem are interesting. If it were me, I think that I'd want to try some kind of fix or partial fix of that issue.

If I was feeling brave, and was being extremely cautious (including taking off the pressure relief valve first, etc), I may want to venture into some kind of acid project to try to clean out some of the scale.

Or, maybe I would first try to flush the system to get rid of some of the scale. In the past, I have opened a gas hot water heater drain valve and found that it had problems draining due to scale and crud blocking the valve. In that case, I tried taking the valve off and putting a flexible probe in the opening to try to clean out some of the crud. Maybe another option would be to connect a hose to the hot water tank drain and force water back into the hot water tank -- maybe by connecting the other end of the hose to a laundry sink faucet. You may need a fitting adapter or two since both the hot water tank drain and the laundry sink drain have male fittings to which a female fitting would need to be attached. If you are lucky and have a laundry sink next to or near the hot water heater, maybe you could use a washing machine hose which has 2 female ends. Or, maybe (if they are not near each other) use a regular hose and a washing machine hose combined so the washing machine hose would serve as the male to female fitting adapter.

Those are just some goofy and cheap tricks that I would probably try just to see if it helps.

[TimR]

This is just idle speculation.

But would adding a water softener eliminate scale and make your water heater last forever?

Of course there's the cost of the equipment, the salt replacement, and the power to run it.

[nestork]

That's exactly what people living in small towns that don't have soft water will do; soften their own water. I don't know how the process works, but all the hardware stores around here sell water softener salt. The houses that get city water don't need that salt because Winnipeg's water is soft, but if you live out of town or in a small town that has hard water, each house will normally have it's own water softener to soften the water the family uses.

[TimR]

Well, what kills a water heater?

Elements wear out but they aren't hard to replace. They'd probably last longer if they didn't scale up.

And the tank wall corrodes through after the sacrificial anodes are gone. They're theoretically replaceable but I don't know anybody who does.

What if you used impressed current instead of sacrificial anodes? Maybe you could get a lifetime water heater, with soft water and corrosion protection.

[nestork]

Tim: Enameled steel water heaters are common in residential applications. Commercial water heaters are usually stainless steel. For example, in my building I have a 100 gallon stainless steel water tank with a copper heating coil inside it. If the copper coil springs a leak, it can be replaced, but the stainless steel tank generally doesn't have any problems, doesn't need an anode rod, doesn't corrode and therefore generally doesn't have any downtime.

But, stainless steel tanks cost considerably more than enameled steel tanks do. My understanding is that my indirect fired water heater cost about $6000 $Cdn.

If you have an enameled steel tank, it IS a good idea to replace the anode rod in the tank every 7 to 10 years. The root cause of enameled steel tanks corroding is the cumulative thermal shocking that the tank endures. Every time the tank heats up and cools down, there is thermal shocking to the tank. The hotter the metal gets before it cools down, the greater the thermal shock with each heating cycle. The most effective way to increase the life of your water heater (besides replacing the anode rod) is to opt for a larger water heater which won't cool down as much when water is drawn out of it each morning for showers and making breakfast.

It's the enamel coating on the inside of the tank that cracks after a certain amount of cumulative thermal shocking. Once that enamel coating cracks, the steel in the tank is exposed to water. If the anode rod is depleted, the steel then starts to rust at the cracks in the enamel. Once the rust works it's way through the steel and a leak develops, you need a new water heater.

[TimR]

Hmm.

If a water softener will prevent the scale, then preventing corrosion shoul d extend the life of the tank.

I see powered anode rods for sale for about $240. I wonder if that's cost effective. That would eliminate the problem of the sacrificial anode being eaten without your knowing. On the other hand, it might not be easy to te ll if the powered circuit is working.

[RobertMacy]

interesting thought, don't have a wet 'n' dry, it's in storage, so NOT allowed to buy another. Plus, I am reluctant to put anything inside th tank. don' want ot do any damage to a liner? But seriously like the idea of vacuuming out that sludge. Plus, dedicated plastic tubing could be reserved just for this application. Not a bad idea at all. I'd be tempted to thow all the sludge and water out and keep refilling from a clean source. The idea of recycling water into my hot water heater FROM a workshop vacuum tank wouldn't go well with Ms. She has me sanitize the heating element before it even gets installed!

[nestork]

I would expect that any company selling those things would have a 1-800 tech support phone number where you could get instructions on measuring the DC voltage impressed on the anode/tank/or both to check the system is working.

[TimR]

We have steel gas lines at work protected by impressed current systems.

We pay a specialist company to come in and do "instant-off" readings periodically. It's not clear to me that the water heater circuits are actually possible to test. It's not as simple as measuring voltage.

[nestork]

It seems to me that it would be because all an impressed current corrosion protection system does is energize the metal to be protected with a small DC voltage. Electrons lost from the metal are immediately replaced by the voltage source, and so the metal doesn't corrode.

I don't know enough about these kinds of systems to tell you one way or another about them, but I wouldn't let your presumption that they may be hard to check to see if they're working or not disuade you from looking into them further. From my limited understanding of how they work, it should just be a matter of checking to see that the voltage source is engergizing the metal you want to protect to the proper predetermined voltage.

It won't cost you anything to look for a 1-800 phone number on one of those impressed current systems and talk to someone more knowledgeable than me about them.

[TimR]

I do think there's some potential here for a greatly increased water heater life.

Of course, we might end up with a "parson's shay."

[nestork]

Certainly, you couldn't go wrong by replacing the anode rod in your water heater every 7 years. The original one put in at the factory is probably tightened with a pneumatic impact wrench, and so you'd probably need to borrow or rent a small air compressor and an impact wrench to take the anode rod out. However, the new one doesn't need to be installed with such a high amount of torque. As long as the water doesn't leak past it's threads, it should be OK. The water heater manufacturer should have instructions on what to use on the threads of the new anode rod which will both prevent leaks and ensure good electrical conductivity between the new anode rod and the tank.

To my way of thinking, replacing the anode rod is the safest way to maximize the life of the tank because it doesn't create new conditions which may cause new problems, like hydrogen gas generation on the anode rod just like you'd get in water electrolysis.

Maybe persue the option of replacing your magnesium anode rod first, and if that doesn't pan out, then consider an impressed current cathodic protection.

[Arnie Goetchius]

Pep boys has one for $10