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Posted by Speedy Jim on June 10, 2006, 2:33 pm
Bill wrote:
> Bill wrote:
>
>>Please bear with me, this explanation man take some time.
>>
>>I purchased a water heater from a large retailer. After it was
>>installed, I read the owners manual and found out the recovery rate was
>>not 25 gal/hr as stated when it was sold, but 17 gal/hr. It was spec'd
>>out incorrectly by the retailer. The retailer has offered me a really
>>great incentive to keep the water heater. The water heater came with
>>two 3800 watt elements. The water heater it replaced was on a 220 line
>>with 12 guage and a 20 amp breaker and had two 4500 watt elements. I
>>live in a warm climate and the two 3800 watt elements are fine in the
>>summer, but I'm not certain about the winter months. I'm just wondering
>>if I might be able to replace the two 3800 watt elements with two 4500
>>watt elements if I need the extra heating in the future? At the price
>>I'm getting the heater and installation, I'd still be way ahead if I
>>replaced the elements.
>>
>>Bill
>
>
> Some additional information. On the new water heater, the bottom
> element is dual wattage 3800/5500. I'd have to upgrade my electrical
> service to run it at 5500 watts. I'm not sure if this matters, but it
> might lend some clue about the water heater handling dual 4500 watt
> elements.
>
OK, I'll weigh in on this.
Your old heater has 4500W elements and has branch ckt conductors
of #12. Right?
Only one element runs at a time.
So, 4500 / 240V = 18.75 Amps
For continuous loads, such as this, the 20A ckt can
only be loaded to 80% of rating = 16 Amps.
The #12 conductors are inadequate (IMHO).
Run #10 and use a 30 Amp CB.
I assume the new heater has a dual-rated element
on the bottom to provide faster heting from a cold start.
5500 / 240V = 22.9 Amps.
The 30 Amp ckt, which you would need anyway, will support
(30 x 80%) 24 Amps so it would be adequate for the new
water heater without altering anything in the heater.
Jim
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