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Nick
 
Posts: n/a
Default 208V instant water heater on 240V

Guys,

I got this 9kw instant water heater from ebay and was told it was
good for 240V/208V and in the book that came with it there is a table
with a bunch of models inc. 208V 50A model and a 240V (208) that
runs 9kw at 240 but 6.3kw at 208.
The model numbers are not listed in this table which is kinda lame and
the unit is German and I think out of production (altho it is 'new').

Since the label outside and the stamp inside both just say 208V my
assumption is that this unit cannot take 240V but the vendor claims it
will.

Does anyone have any thoughts on how one might figure this out without
risking a fire or something?

The element resistance is 4.9 Ohms which by my math gives ~8830W which
would suggest this unit cannot run 240 as that would be over 11kw.

Think I'm gonna send it back.
  #2   Report Post  
Matt
 
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Default

I think that's your best move, Nick.

You probably aren't at risk of a fire, but I'd bet the element doesn't
last long.

If nothing else - if you do wire it up, you'll probably be paranoid
about it from the first power up.

Ship it back gets my vote.

  #3   Report Post  
Len Shure
 
Posts: n/a
Default

Electriccal voltage vaires though the day. Your 120 volt wiring runs
from 105 to 130 maybe. Voltage in a wire is kind of like pressure in a
water line. Make sure you have the right circuit breakers and wire size
and you probably will be ok.

Nick wrote:
Guys,

I got this 9kw instant water heater from ebay and was told it was
good for 240V/208V and in the book that came with it there is a table
with a bunch of models inc. 208V 50A model and a 240V (208) that
runs 9kw at 240 but 6.3kw at 208.
The model numbers are not listed in this table which is kinda lame and
the unit is German and I think out of production (altho it is 'new').

Since the label outside and the stamp inside both just say 208V my
assumption is that this unit cannot take 240V but the vendor claims it
will.

Does anyone have any thoughts on how one might figure this out without
risking a fire or something?

The element resistance is 4.9 Ohms which by my math gives ~8830W which
would suggest this unit cannot run 240 as that would be over 11kw.

Think I'm gonna send it back.

  #4   Report Post  
Beeper
 
Posts: n/a
Default

Just my opinion: Foreign products are precisely engineered. There is usually
no room for error.Products engineered in the states are usually over
designed. Probably because of all the lawsuits by morons that don't follow
the directions and then want to sue when something goes wrong......Did I say
that out loud? If your german made model does not call out for 240 then I
would either contact the manufacturer, someone familiar with that model, or
send it back.
"Nick" wrote in message
...
Guys,

I got this 9kw instant water heater from ebay and was told it was
good for 240V/208V and in the book that came with it there is a table
with a bunch of models inc. 208V 50A model and a 240V (208) that
runs 9kw at 240 but 6.3kw at 208.
The model numbers are not listed in this table which is kinda lame and
the unit is German and I think out of production (altho it is 'new').

Since the label outside and the stamp inside both just say 208V my
assumption is that this unit cannot take 240V but the vendor claims it
will.

Does anyone have any thoughts on how one might figure this out without
risking a fire or something?

The element resistance is 4.9 Ohms which by my math gives ~8830W which
would suggest this unit cannot run 240 as that would be over 11kw.

Think I'm gonna send it back.



  #5   Report Post  
RBM
 
Posts: n/a
Default

I second Mark's idea. In the USA residential heating products are generally
wired for 240 volts, but if used in some commercial buildings where you may
have 3 phase 208 volt services, they want you to know that the heater won't
get as hot. In your case you're doing the reverse and the elements will
overheat which will shorten their life.
wrote in message
...
More Ebay junk !!!!
Some people never learn !!!!

Send it back, waste more money on shipping, then close your ebay
account.
Next go to your local HD or plumbing supply and buy the proper heater.
You wont get ripped off on shipping and handling there, and you wont
risk a fire.

Mark


On Sat, 07 May 2005 00:12:31 GMT, Nick
wrote:

Guys,

I got this 9kw instant water heater from ebay and was told it was
good for 240V/208V and in the book that came with it there is a table
with a bunch of models inc. 208V 50A model and a 240V (208) that
runs 9kw at 240 but 6.3kw at 208.
The model numbers are not listed in this table which is kinda lame and
the unit is German and I think out of production (altho it is 'new').

Since the label outside and the stamp inside both just say 208V my
assumption is that this unit cannot take 240V but the vendor claims it
will.

Does anyone have any thoughts on how one might figure this out without
risking a fire or something?

The element resistance is 4.9 Ohms which by my math gives ~8830W which
would suggest this unit cannot run 240 as that would be over 11kw.

Think I'm gonna send it back.






  #6   Report Post  
Charlie Bress
 
Posts: n/a
Default

Measuring the resistance of the heating element when it is cold does not
give a valid result for calculating power.
The resistance will be higher as soon as the element heats up and conversely
the power will go down.

As a sanity check on this statement, do the same thing with light bulb or
with a toaster and compare your calculations with the wattage ratings of
those devices.

Charlie

"Nick" wrote in message
...
Guys,

I got this 9kw instant water heater from ebay and was told it was
good for 240V/208V and in the book that came with it there is a table
with a bunch of models inc. 208V 50A model and a 240V (208) that
runs 9kw at 240 but 6.3kw at 208.
The model numbers are not listed in this table which is kinda lame and
the unit is German and I think out of production (altho it is 'new').

Since the label outside and the stamp inside both just say 208V my
assumption is that this unit cannot take 240V but the vendor claims it
will.

Does anyone have any thoughts on how one might figure this out without
risking a fire or something?

The element resistance is 4.9 Ohms which by my math gives ~8830W which
would suggest this unit cannot run 240 as that would be over 11kw.

Think I'm gonna send it back.



  #7   Report Post  
Doug Miller
 
Posts: n/a
Default

In article , Len Shure wrote:
Electriccal voltage vaires though the day. Your 120 volt wiring runs
from 105 to 130 maybe.


It varies, but nowhere nearly that much. If it's down to 105, that's a *big*
problem. Variation is typically not more than a volt or two.

Voltage in a wire is kind of like pressure in a
water line. Make sure you have the right circuit breakers and wire size
and you probably will be ok.


No, he probably will not. The element is rated for 208V. He's going to be
pushing a fifteen percent overvoltage through it, and it's probably going to
burn out very soon.

Please confine your advice to subjects you know something about. Inaccurate
electrical advice is dangerous.

--
Regards,
Doug Miller (alphageek at milmac dot com)

Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?
  #8   Report Post  
 
Posts: n/a
Default

"No, he probably will not. The element is rated for 208V. He's going to
be
pushing a fifteen percent overvoltage through it, and it's probably
going to
burn out very soon. "

I seriously doubt that a 15% overvoltage in a heating element that is
surrounded by water is going to burn it out. Just because the instant
water heater is labeled for 208V, doesn't mean that's the max rating of
the individual components, like the heating element. As an example,
some SPA/Hot Tubs are sold as either 120V or 240V. They are identical
except the power packs are slightly different. Both units have the
exact same heating element. If you look at the label on the 120V SPA,
that's what it will say, even though the heating element can take 240V.
You can switch it to 240V by simply changing the power pack, leaving
the heater element as is. In that case the heater then puts out 6KW,
instead of 1.5KW when wired for 120V.

BTW, I'm not saying I'd used this Ebay water heater myself, only that
IMO, it's likely it would in fact work.

  #9   Report Post  
RBM
 
Posts: n/a
Default

You may be missing the point. If you put two 120 volt elements in series you
can operate them at 240 volts, but you can't take one 120 volt element and
operate it at 240 volt (not for long) These water heater elements are
designed to be under water and produce a certain amount of heat at a precise
voltage. If you power it with more than the rated voltage, it will both get
hotter and shorten the life of the element
wrote in message
ups.com...
"No, he probably will not. The element is rated for 208V. He's going to
be
pushing a fifteen percent overvoltage through it, and it's probably
going to
burn out very soon. "

I seriously doubt that a 15% overvoltage in a heating element that is
surrounded by water is going to burn it out. Just because the instant
water heater is labeled for 208V, doesn't mean that's the max rating of
the individual components, like the heating element. As an example,
some SPA/Hot Tubs are sold as either 120V or 240V. They are identical
except the power packs are slightly different. Both units have the
exact same heating element. If you look at the label on the 120V SPA,
that's what it will say, even though the heating element can take 240V.
You can switch it to 240V by simply changing the power pack, leaving
the heater element as is. In that case the heater then puts out 6KW,
instead of 1.5KW when wired for 120V.

BTW, I'm not saying I'd used this Ebay water heater myself, only that
IMO, it's likely it would in fact work.



  #10   Report Post  
 
Posts: n/a
Default

"You may be missing the point. If you put two 120 volt elements in
series you
can operate them at 240 volts, but you can't take one 120 volt element
and
operate it at 240 volt (not for long) These water heater elements are
designed to be under water and produce a certain amount of heat at a
precise
voltage. If you power it with more than the rated voltage, it will both
get
hotter and shorten the life of the element "

I'm not missing anything. The example I gave covers it quite nicely
and has nothing to do with putting two elements in parallel.

"These water heater elements are
designed to be under water and produce a certain amount of heat at a
precise
voltage."

There's nothing "precise" about what is simoly a resistor surrounded by
lots of cooling water. Sure there's some upper current limit, but we
have no way of knowing what the actual rating on the heater element of
the OP's unit is, only the rating on the plate of the device itself.
And the upper limit is very likely a lot more than 15%.



  #11   Report Post  
Matt
 
Posts: n/a
Default

Nick -

This thread is quickly turning into a ****ing match about who has the
most knowledge of heating elements underwater.

Soon, people are going to be called out for spelling and typo's.

You have a chance to save us all, if you act quickly!

Are you keepin it, or shipping it back?

  #12   Report Post  
HorneTD
 
Posts: n/a
Default

Nick wrote:
Guys,

I got this 9kw instant water heater from ebay and was told it was
good for 240V/208V and in the book that came with it there is a table
with a bunch of models inc. 208V 50A model and a 240V (208) that
runs 9kw at 240 but 6.3kw at 208.
The model numbers are not listed in this table which is kinda lame and
the unit is German and I think out of production (altho it is 'new').

Since the label outside and the stamp inside both just say 208V my
assumption is that this unit cannot take 240V but the vendor claims it
will.

Does anyone have any thoughts on how one might figure this out without
risking a fire or something?

The element resistance is 4.9 Ohms which by my math gives ~8830W which
would suggest this unit cannot run 240 as that would be over 11kw.

Think I'm gonna send it back.


If you got a good price on the unit then consider using an auto
transformer to buck the voltage down to 208. You have to way the cost
of installing the auto transformer against the added cost of switching
to a 240 volt unit.
--
Tom H
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