Tankless, instant hot water heater

Discussion in 'General Electronics Chat' started by jjj, Aug 12, 2010.

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  1. jjj

    Thread Starter Senior Member

    Feb 25, 2007
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    For a change, I have got an electrical problem. Could you respectable experts please give me some much needed advice?
    On eBay I bought a couple of these tankless, instant hot water heaters for use on 220VAC:


    http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=300454789352&ssPageName=ADME:X:RTQ:US:1123

    Towards the bottom of this page they says that it has to be earthed (not on Neutral).
    It heats up OK, yet the problem is that I measured about 100V between the water and (water input) copper pipe and (only) when I try to connect the earthing wire from the heater to the copper pipe, the automatic fuse goes off. The same happens if I try to connect this earthing wire on Neutral of 220V.
    This hot water heater uses an open (uninsulated) resistor/ heating wire as element and water conducts. How to earth out the residual 100V?
    Here it shows the inside of the heater:

    http://www.productoracoral.com/repuestos_eng.html
     
    Last edited: Aug 12, 2010
  2. sceadwian

    New Member

    Jun 1, 2009
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    I think the intention is that the shower head be completely electrically isolated. You'd have to use PVC feeds of a sufficient length to prevent voltage from seeping into nearby copper tubing, this could be difficult or impossible if you have hard water issues in your area.

    I'm not sure about common practice or the law where you're at but if I'm not mistaken using household plumbing as an earth ground for an electrical system is illegal.
     
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  3. BillB3857

    Senior Member

    Feb 28, 2009
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    How do you spell "ELECTROCUTION"?? Water, with mineral content, is a conductor. If the heating element is in direct contact with the water going through the unit, the water will become "Hot" in more ways than intended.
     
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  4. someonesdad

    Senior Member

    Jul 7, 2009
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    By looking at the last link you given in your post and looking at the maintenance video link, it appears to me that this device is immersing a heating coil connected to the 240 VAC line directly in the water you take a shower in. If this heating coil is not insulated electrically from the water, this is insane -- it's worse than dropping a hair dryer in the bathtub. I can't see how they could make this thing safe, since the brass screws clearly aren't insulated from the water.

    I would NEVER install such a unit in my home! I can't believe that this company gets away with selling such a thing in the US. Am I missing something? I'd like the knowledgeable electricians on this board to comment on this product and see what they think about it. Unless someone steps in with a very credible explanation of why this thing is safe, I recommend you immediately disconnect the thing and send the product back!!!
     
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  5. jjj

    Thread Starter Senior Member

    Feb 25, 2007
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    Thanking you all for your good advice. Luckily I did my homework first, by putting it merely to the test, near the yard's sink.
    I connected the unit to the garden hose, yet measuring with the one multimeter probe in the water and the other to the water tap, I measured almost 100V and touching both at the same time... is quite dramatic! I wouldn't want to stand in that type of electrified shower! I sent your responses to the manufacturer export@productoracoral.com and see what they have to add... Thx again for your life saving help!
     
  6. sceadwian

    New Member

    Jun 1, 2009
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    No Bill/someonesdad it won't, the instant it leaves the shower head the air gap will block any AC or DC current flow, 100% perfectly harmless, as long as the head itself is isolated. Again as far as legalities go this is seriously on the sketchy side.

    With bathtub and a hair drier you're in direct contact with a pool of liquid water with dissolved solids and an electrical conductor. Water droplets are not the same, at the moment they leave the nozzle and separate they are electrically isolated. This however won't do a damn bit of good to save the poor soul that reached up and touches the nozzle directly.

    I'm going to guess that the manufacturer is going to spout back the exact same things it does in it's advertisements. This device is not EVER ment to be touched by anything directly electrically grounded or by a human being in close proximity. If isolation of the device from the user and the stream of water from the spout can be assured there is zero risk.
     
  7. BillB3857

    Senior Member

    Feb 28, 2009
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    Please post the manufacturer's response. It should be quite interesting!
     
  8. beenthere

    Retired Moderator

    Apr 20, 2004
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    If the shower head is electrically hot and the shower drain is metal and in contact with a copper or iron drain pipe, that is an electrocution hazard. Same for the shower controls. That is relying on luck and not design to keep you safe.

    "Normal" water heaters use elements buried in a ceramic material inside a nickle alloy cover. Electrical connections are made outside the tank and insulated from the water.
     
  9. jjj

    Thread Starter Senior Member

    Feb 25, 2007
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    It's getting interesting! In my Test, I didn't use the shower head o the unit. Instead, I just screwed a flexible shower hose with head onto the unit (the suggested alternative, shown in the manufacturer's video). Yet, when I touched the running hot water from the shower head and the tap, I felt quite a jolt! I then measured about 100V. That means, it's not save, because the victim in the shower has to touch the tap to close the water flow, unless all plumber items are made of plastic. Even then the person's body conducts some Earth, I like to think, because even I touched only the running warm water from the unit, I felt a tingling sensation on my finger tips.
     
    Last edited: Aug 12, 2010
  10. BillB3857

    Senior Member

    Feb 28, 2009
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    Or step on the drain!!!
     
  11. scratch

    Member

    Aug 6, 2010
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    The only way to make that device safe is to not use it.
     
  12. someonesdad

    Senior Member

    Jul 7, 2009
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    In theory, I would agree -- but, in practice, are you sure a chaotic system won't provide a conduction path between you and the grounded metal drain? Would you be willing to bet your life on it? I sure wouldn't.

    I'd also worry about a person accidentally touching the exit point of the water; take a look at the maintenance video and the guy doing the talking nearly touches it with the hands on his head.

    This is a seriously flawed product design.
     
  13. marshallf3

    Well-Known Member

    Jul 26, 2010
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    I honestly don't see how they could legally sell this in the U.S. or anywhere else for that matter. I'm guessing they assume that by grounding the thing it becomes voltage-neutral. Soeone's going to catch up with them in very short order and let's hope it's a simple cease and desist instead of a lawsuit over killing someone.
     
  14. jjj

    Thread Starter Senior Member

    Feb 25, 2007
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    Well, when you consider that it's very likely that someone gets killed, then its not to be taken lightly. They should at least be fined for bringing this lethal toy onto the market or else anyone will try his luck in marketing this kind of dangerous consumer traps to make money.
    My electronics hobby knowledge helped me to put it to the test and so, prevent electrocuting myself. Others mightn't be as lucky...

    On the other hand, with 110V it might only be 50V in the hot water... because with 220V I measured 100V. Right?
     
  15. jjj

    Thread Starter Senior Member

    Feb 25, 2007
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    Just another quick question:
    Would it be possible to use 35V heater wire via transformer with high Amps?
    How many Amps would the Trafo have to equal, say 1.5KW or 2KW at 220V?
     
  16. retched

    AAC Fanatic!

    Dec 5, 2009
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    That is simply amazing.

    "Are you tired of your wife and kids? Let our new hot water/electric chair take care of your problems!"

    Ok.. not really used in there advertising, but it might as well be.

    If this device was connected to a GFCI, It would trip the instant water hit it. It is truly astonishing that this is being sold.

    ....only on ebay...
     
  17. gwbissett

    New Member

    Aug 13, 2010
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    Hi all

    I would not use a unit designed this way, I understand the intent, but this is way too risky, water does not conduct electricity unless you are earthed or creating a shorter distance to the earth, in this case all fixtures like taps ,drain covers should be earthed in a normal environment{not in africa :)}
    In that instance you will be creating a conductor for the electricity to pass to earth, thus the risk.
    These guys are bonkers or have not thought it through.

    :(
     
  18. retched

    AAC Fanatic!

    Dec 5, 2009
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    I agree with bonkers.
     
  19. BillB3857

    Senior Member

    Feb 28, 2009
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    While reading the instructions, I noticed they were talking about water being supplied from a tank. Could be this unit is directed toward undeveloped areas where water is pumped up to a barrel on the roof and power is derived from an un-grounded generator. Still way to marginal for me.
     
  20. marshallf3

    Well-Known Member

    Jul 26, 2010
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    We can make up reasons and theorize about this all day, somebody that has a few spare minutes should write UL & the FTC to notify them of this potentially life-threatening product.
     
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