OT: Instant hot water heater spatters

We have one of those small 1/3rd gallon instant water heaters under the sink, with its separate little tap on the sink. To make instant hot drinks or to clean stuff. Worked flawlessly for many years. Recently it started splattering, air bubbles come out. That wouldn't be so bad but sometimes it splatters across the cup you are holding and it can burn fingers. It's this one (3MB file):

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I unplugged it, ran it for gallons, much more than the thing holds. It's plumbed into the regular faucet next to it and that doesn't splatter. No leaks anywhere. Given that I ran more water than could ever be in that boiler plus short 1/4" branch-off line and it still has air bubbles I am puzzled. Where could those come from? Why does the faucet on the same supply line not produce any bubbles?

The sediment content of our water is very low, so that's unlikely.

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Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg
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Is the thermostat set too high, or failed, and the water is boiling, or near boiling such that, pressure drops when you open spout it bubbles? ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Reply to
Jim Thompson

Assuming the water is hot enough that steam can form, at all, I think it's a given that there must be particulates of the right size to be encouraging bubble formation somewhere and that this is the change you are looking for. (I would guess that the "air bubbles" are really "steam." So I would have first thought about mineralization. But I gather you are saying "no" to that. And I don't know if the water is hot enough (together with altitude), besides.

Your test would seem to preclude air arriving from the source, so the system itself remains the suspect.

Jon

Reply to
Jon Kirwan

Which is the first item on the troubleshooting sheet ;-) ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Jim Thompson

The instructions say that steam will come out when first plugged in. If it still steams, the thermostat needs to be adjusted.

Maybe the thermostat went south? Did you try to re-adjust it? The water may be boiling .

Cheers

Reply to
Martin Riddle

I know that but it's actually set lower than normal. Also, this does not explain that I still get the same amount of bubbling and splattering after having sent 3-4 gallons through the thing. By then it was totally cold water.

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Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

Ok, but I've run gallons and gallons through the thing while unplugged. It kept constantly throwing out the same number of (now cold) bubbles per minute while the main faucet connected to the same line doesn't.

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Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

You can hear when it boils. I set the thermostat a bit lower when I installed it many years ago. You can hear a brief onset of a boil on at the end of every heating cycle but it turns off right at that point. The factory setting had it making boiling noises much longer. This pattern and the noise is still the same as years ago. But now we get bubbles, even when the heater is unplugged and cold water streams out. No matter how long I let it stream out.

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Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

The only thing I can think of is it is totally filled up with calcium deposits, like a foam, and that is where all the bubbles are hiding. You might try filling it with 50 % vinegar solution and letting it sit for a while and see if a huge amount of crud comes out. If so, repeat until the crud is reduced to a reasonable level, then rinse well before hooking the heater back up.

Jon

Reply to
Jon Elson

That would explain it, although our water is very low in minerals. Getting vinegar into it would require me to undo the plumbing I guess.

The weird thing is that the sheer amount of bubbles already seems to be more than such a tiny 1/3gal boiler could ever hold.

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Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

Just replace it ;-) ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Reply to
Jim Thompson

Tempted. But last time I did that I banged my head a lot. It's tight down under the sink. Then there are those darn compression joints. Out here they keep leaking ever so slightly until you torque them down to white-knuckle level.

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Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

Dissolved gasses coming out of solution? Numbers and graphs here:

Could be that there has been a change in your upstream supply that is bringing in a source with a higher than usual amount of dissolved gasses. Heat it up and presto -- air bubbles.

Reply to
Rich Webb

I've suspected that. However, I just repeated the test that kind of says it can't be: Ran it cold. Comes off the same line as the filtered water faucet of same (small) diameter, both get filtered water. The filtered-water faucet never has any bubbles, the hot-water dispenser bubbles like crazy even well after all water in the tank has gone out and fresh water comes in.

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Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

Actually, bubbles even when cold suggests a pin-hole leak somewhere. Maybe the valve is worn and leaks/sucks air when activated. ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Reply to
Jim Thompson

That's where your air leak is. ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Reply to
Jim Thompson

Not anymore, else it would drip. You can't have air coming in when there is 65psi in the water line.

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Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

Not true its called the Bernoulli effect, That can suck in air. if there is enough pressure with the water flow stopped, it will seal itself.

Cheers

Reply to
Martin Riddle

Ok, but then something should be wet under the sink. It's all under pressure. AFAIK this unit doesn't have any over-pressure valve.

We do have a carbon cartridge water filter up front of it. Also feeds a cold-water outlet and that does not show any bubbles. Could the filter still have anything to do with it?

--
Regards, Joerg 

http://www.analogconsultants.com/
Reply to
Joerg

So it's the valve. Or, another thought... does that gadget have a vacuum break? ...Jim Thompson

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| James E.Thompson                                 |    mens     | 
| Analog Innovations                               |     et      | 
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Reply to
Jim Thompson

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