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Old 12-14-2012, 08:47 PM   #31
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Is it OK to power a 220v tankless with only 120v?


So you are saying you ignored the manufacturers instructions.

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Old 12-14-2012, 09:32 PM   #32
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Is it OK to power a 220v tankless with only 120v?


Nope. Even talked to them on the phone and install is working great!
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Old 12-15-2012, 07:43 AM   #33
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Is it OK to power a 220v tankless with only 120v?


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"Tankless" has no "tank" thus no pressure build up so TPR valves are not required but you already know that, right?
But don't take my word for it, ask a manufacturer. "Installation of our tankless water heater is quick and easy. Under normal conditions, it requires no pressure relief valve. "
Well, my Rheem tankless water heater DOES require a TPR valve. Said so in the instructions when I installed it.

If your hack job of an installation makes you happy, so be it. But it's still a hack job. Beware the law of unintended consequences.

Last edited by md2lgyk; 12-15-2012 at 06:14 PM.
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Old 12-15-2012, 07:57 AM   #34
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Is it OK to power a 220v tankless with only 120v?


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Nope. Even talked to them on the phone and install is working great!
I would bet they will not put that in writing as it contradicts their written instructions.
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Old 12-16-2012, 05:45 PM   #35
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Is it OK to power a 220v tankless with only 120v?


Instructions say TPR is not required and 7.2max Kw is equal to 30amps at 240v.
Sorry you guys can't do math but keep on hating with your ignorance.
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Old 12-16-2012, 06:10 PM   #36
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Is it OK to power a 220v tankless with only 120v?


I would be curious which exact model you purchased.
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Old 12-16-2012, 08:56 PM   #37
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Is it OK to power a 220v tankless with only 120v?


If you look on their web site it says relief valve not required unless by local code.
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Old 12-16-2012, 10:27 PM   #38
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Is it OK to power a 220v tankless with only 120v?


If the unit came with a T&P valve and you removed it you have voided the units listing and warranty. I would reinstall it and run a line from the T&P to somewhere where it can drain if needed.
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Old 12-17-2012, 12:04 AM   #39
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Is it OK to power a 220v tankless with only 120v?


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Beware the law of unintended consequences.
I hate that law. I don't think they realized what would happen when they passed that law.
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Old 12-17-2012, 07:00 AM   #40
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Is it OK to power a 220v tankless with only 120v?


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If you look on their web site it says relief valve not required unless by local code.
Aah, there's the gotcha. I doubt there's a jurisdiction anywhere in the U.S. that would NOT require a TPR valve. I'm pretty sure the requirement is in the UPC, and probably the IPC as well.
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Old 12-17-2012, 07:09 AM   #41
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Is it OK to power a 220v tankless with only 120v?


PEOPLE!
Mr. WonderWorm is going to do what suits him, regardless of the rules and consequences. Do we really think all this chatter is going to convince someone like this that they are wrong???

I say let this pathetic topic die to the bottom of the forum.
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Old 12-17-2012, 05:49 PM   #42
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Is it OK to power a 220v tankless with only 120v?


I found this interesting.

In our rural area there are still many 60 amp services.

Years ago this was fine, as the ranges were propane, and the clothes were dried on the line, or with a gas dryer and the heat was usually oil supplemented with wood or kerosene.

I even had a friend growing up that had a wood fired hot water in his house. They would start a nice hot kindling fire under it, wait 20 minutes, and take a shower. There was no electricity run there yet.

When the hot water heater died, they were often replaced with electric as they were cheaper and electricity was being billed as much less to use than propane.

Often the electrician (or plumber) would wire it up for 120v as there wasn't room in the panel for a 240v hook up (think old screw in fuses), or the 60 amp system just couldn't handle it as more and more electrical appliances were added. Coffee percolators, those new fangled TV things, clock radios, phonographs, (and remember those early electronics were full of power sucking tubes) electric blankets, well, you get the idea...

With a 30 gallon tank type water heater, it just took about 4 times longer to heat up. Then you had enough to do the wash, take a bath (on Saturdays), do the dishes, rinse off the dog...

You just had to plan your hot water usage, but things moved slower then.

So, yes, it was a pretty common practice to wire 240v tank type water heaters to 120v.

Electricians around here usually check for this when the service is upgraded and rewire them to 240v routinely.

I have heard stories about callbacks because the homeowner thought that something terrible was wrong with the hot water heater, when it was simply doing what it was originally supposed to.

Tankless units are a whole different animal and most of decent capacity require 2 separate 40 or 60 amp circuits to feed them.

They can draw 30 to over 100 Amps.

So.... long story, but 120 volts feed on a 240 tankless just doesn't make sense....

And we need more and more and more electricity don't we?

I'm getting chilly, I think I'll throw another log on the fire...
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Old 12-17-2012, 08:45 PM   #43
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Is it OK to power a 220v tankless with only 120v?


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PEOPLE!
....regardless of the rules and consequences. Do we really think all this chatter is going to convince someone like this that they are wrong???
I say let this pathetic topic die to the bottom of the forum.
Please state the consequences and rules you were referring to and where I am wrong. It seems as though the people you are speaking to are desperate to be proven right in their rush to judgements, in spite of all the evidence and results that point to them being flat out wrong.
In the meantime I will continue to enjoy my new clean install, extra closet space, perfectly working tankless, and extra cash with my lower electric bill each month.
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Old 12-17-2012, 09:05 PM   #44
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Is it OK to power a 220v tankless with only 120v?


I was trying to be informative and humorous in my post above and bring some perspective into this whole issue.

I hope you enjoy your new water heater, which you wired for 240 volts after all.

Prove us all wrong and rewire it for 120v and let us know your results.
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Old 12-17-2012, 09:37 PM   #45
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Is it OK to power a 220v tankless with only 120v?


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I was trying to be informative and humorous in my post above and bring some perspective into this whole issue.
I hope you enjoy your new water heater, which you wired for 240 volts after all.
Prove us all wrong and rewire it for 120v and let us know your results.
I wasn't responding to you, your post was informative and humorous. It was a response to speedypetey, md2lgyk, rjniles and the other haters who have been claiming that a 240v tankless heater installed on a 240v #10 line at 30 amps as a single point of use water heater was somehow a "hack job" install when it is per specs and works great so it is anything but. So yes, I have been proving them wrong every single day since I installed it and will continue to.

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