Electric Water Heater Element replacement

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RetiredInFL

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Hello all ... just came across this forum (thanks Google).

Just had a 15 year old AO Smith Electric WH replaced in a home we recently moved into. The original WH was a 4500 Watt 40 Gal unit and was replaced with a 50 Gal 3800 Watt AO Smith Model 100 by a local plumber. Would have done the job myself except lifting a 120 LB tank 3 feet up onto a platform ain't good for my 75yr old back! It was my bad not specifying 4500 Watt (they make both) but it never crossed my mind. In any case, I see replacement elements are cheap enough and I consider myself a long time DIY'er and have previously rewired much of my previous home so dealing with electrical is not an issue.

I am wondering if I can simply replace the 2x3800 w elements with 2x4500 w elements. From reading it seems both TANK versions are IDENTICAL except for the element itself. 15yr old home, The breaker is 30AMP and wiring from fuse panel to tank is 10 guage, which was fine and proper spec on the original 4500 watt tank. My only concern is if the INTERNAL WIRING INSIDE THE TANK (which is only a couple feet of wire) is the same between the 3800 & 4500 watt units and the T-Stats are the same (can't see any reason for them being different). Just wondering if anyone knows. I would guess it's the same but just want to be sure.

Thanks!
 

WorthFlorida

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You must first check the circuit breaker. 20 amp/12 gauge wire it must be 3800 watt. 30 amp/10 gauge is for 4500 watt.

A 15 year old home and it will be 30 amp breaker

FYI....
There are many older homes with 12 gauge wired in Florida. Many people (DIY'ers) replaced an original 3800 watt heater with 4500 heaters and the wire was not up to snuff. 4500 watt elements takes 18 amps so most 20 amp breakers may not trip. You want to be at full load not more than 80% of the rated breaker. 20 amp with a continuous draw of no more 16 amps, 30 amp with a continuous draw of no more than 24 amps. Just remember the breaker protects the wire, not the appliance.

Both tanks are identical including the internal wiring and thermostats. 3800 watt elements and heaters are still made for the millions of homes wired (1950-1970-ish) with 12 gauge wire. It may be why the plumber installed a 3800 watt unit because its code and liability.

If you have a 20 amp breaker, the best way is to install a CASH-ACME tank booster and increase the water temperature. I installed one at my church and one at my son's house. It makes a 50 gallon tank performs as a 90-100 gallon tank. Tank Booster Pro is the model I prefer. https://www.cashacme.com/us/en/tmvs
 
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RetiredInFL

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You must first check the circuit breaker. 20 amp/12 gauge wire it must be 3800 watt. 30 amp/10 gauge is for 4500 watt.

There are many older homes with 12 gauge wire in Florida. Many people (DIY'ers) replaced an original 3800 watt heater with 4500 heaters and the wire was not up to snuff. 4500 watt elements takes 18 amps so most 20 amp breakers may not trip. You want to be at full load not more than 80% of the rated breaker. 20 amp with a continuous draw of no more 16 amps, 30 amp with a continuous draw of no more than 24 amps. Just remember the breaker protects the wire, not the appliance.

Both tanks are identical including the internal wiring and thermostats. 3800 watt elements and heaters are still made for the millions of homes wired (1950-1970-ish) with 12 gauge wire. It may be why the plumber installed a 3800 watt unit because its code and liability.

If you have a 20 amp breaker, the best way is to install a CASH-ACME tank booster and increase the water temperature. I installed one at my church and one at my sons house. it makes a 50 gallon tank performs as a 90-100 gallon tank. This is the model I prefer. https://www.cashacme.com/us/en/tmvs


Thank you for that!! As mentioned in OP it is 10 gauge wire and 30 amp fuse. Home is 15yrs old. Original tank was 4500 watts. The plumber just screwed up and I never thought there was a lower wattage version.
 

Gagecalman

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It's a shame he installed that with 3800W elements.
I just installed a Rheem with 5500W elements that I got at HD.
 

RetiredInFL

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It's a shame he installed that with 3800W elements.
I just installed a Rheem with 5500W elements that I got at HD.

Really surprised me as well. There are close to 60,000 homes here and all, other than the small number of gas properties, started with the same AO SMITH 4500 watt tanks.
 
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