OT: Instant hot water heater spatters

I'm always nervous about the potential for a flood if something is weakened. It's easy to have damages that exceed $20-30K if nobody is around when it happens.

Best regards, Spehro Pefhany

Well, if the old one was clean inside, then this one probably is, too. No idea, then, where the bubbles come from.

Jon

Yeah, I think I'll pass on the muriatic acid. That's almost like shooting a mosquito with a cannon. Then mosquito is going to be gone alright but ...

You seem wedded to the idea that an air leak *has* to leak water. You have evidence that there is air getting into the system, so why is the lack of a water leak a problem? What possible explanation do you have? Maybe it is a leak that seals when the pressure is high, but can suck air when the pressure drops under use?

That is the idea of using vinegar. It is enough to remove some minerals, but won't attack the metal as long as it doesn't remain in contact with the metal too long. Some metals are subject to attack even from vinegar like Aluminum. It can discolor if left in contact with even weak acids for very long. It would take a long time to corrode it structurally very much though.

You could be accidentally getting a venturi effect on the outflow side. Somebody else already mentioned the venturi or Bernoulli principle which would be pulling air into the outflow.

Air compressor powered paint sprayers (Bink) pull paint out of the paint pot similarly, though air and liquid are switched around. (Both fluidic)

The quantity and shot gun behavior of the air gives me doubts though.

Joerg schrieb:

Hello,

there is always some air soluted in water. Under pressure more air may be soluted. Cold water may solute more air than hot one. Temperature is rising, pressure is sinking, air bubbles are generated. It's only physics.

Bye

Yeah, but it also happens when the whole thing is cold.

It's cavitation, resulting from very complex hydrodynamics of flow through the heater together with material properties of the surfaces. It doesn't ta ke an air leak. If you can't replace the heater core, replace the whole thi ng. The countertop one cup instant heater small appliances would probably b e better because they don't require any plumbing.

heater together with material properties of the surfaces. It doesn't take an air leak. If you can't replace the heater core, replace the whole thing. The countertop one cup instant heater small appliances would probably be better because they don't require any plumbing.

"Cavitation is the formation and then immediate implosion of cavities in a liquid". Cavitation is a vacuum formed by the hydrodynamics of propellers, impellers and similar objects. The bubbles disappear very rapidly when they move away from the low pressure area. This is why anyone even cares about cavitation. It produces a lot of noticeable noise if you are trying to be quiet like a submarine and can erode surfaces if it happens a lot.

Cavitation won't produce bubbles that last long enough to show up in the water coming out of a faucet.

You're wrong about that, know-it-all, cavitation is major issue for flow through a constriction like a valve port.

heater together with material properties of the surfaces. It doesn't take an air leak. If you can't replace the heater core, replace the whole thing. The countertop one cup instant heater small appliances would probably be better because they don't require any plumbing.

Say what?

Jamie

through a constriction like a valve port.

Do you have anything to support your statement that I am wrong? Cavitation bubbles are vacuum bubbles. They disappear very quickly. That is not saying they don't exist in a valve, that is saying they don't make it out of the faucet. They cause a problem when they collapse and create a *very* high pressure jet resulting in erosion of the surface.

I'm not a know it all. I don't know why you dispute facts. :) Why be belligerent? If you disagree, give me some facts to support your point. I quoted the article that you referenced. Was my quote incorrect?

Note that on these water heaters, the valve is on the INLET side. The tank is unpressurized and if the water boils in the tank it just comes out of the faucet.

It's toast. Replace it. Mine did the same thing before it started leaking water under the sink.

Joerg, Several years ago, my house water heater started doing the exact same thing. Lots of bubbling from the faucets, even though they were many feet away from the water heater. The problem turned out to be a heating element that had split open inside the tank, exposing the heater wire to the water, and was boiling the water inside the tank. The circuit breaker didn't trip. The water at the faucet was exceedingly hot... don't know if was boiling temperature, but it surely spat and sputtered like it was.

Fixed it with a new heater element. Never a moment's trouble from then on.. Cheers, Dave M

he

w through a constriction like a valve port.

Technically it may be called 'flashing' where the downstream pressure is lo w enough for the bubbles to remain vapor. The spatter is a relaxation effec t where an airspace accumulates until enough back pressure develops to brea k it loose and thereby cause the spatter effect.

Ok, but why then does the bubbling still happen with the heater unplugged and everything totally cold? Still got to take the top apart, but had some unplanned trips to the dentists. Restoration -> root went off, big time -> root canal.

That is also possibly a worst case scenario if there is dissolved air in your water (or worse still methane from fracking).

Try slowly boiling some cold water on the stove to see how much air is actually in there. I'm with JT that a broken thermostat is allowing flash boiling of water when you open the tap as the root cause.

Measuring the temperature of the water in a plystyrene cup that comes out might be illuminating. If we are right then it will be close to 99C. (calibrated thermometer immersed to correct depth)