Have an interesting situation. Daughter's 1950 ranch house has two 50 gallon hot water heaters. One hot water heater is for the two full bathrooms and the other hot water heater for the kitchen and laundry (washer, dishwasher and sink).

Before she bought the house, there was a break in the hot water line under the living room floor (slab with wood flooring). Instead of breaking up the floor, and new hot was heater was added at the far end of the house with the two full bathrooms and the water lines were rerouted.

The older hot water heater now supplies the kitchen and laundry is due to be replaced.

Here is the problem ... this older hot water heater is powered with 12 gauge wiring on a 20 amp breaker. Either I pull 10 gauge wire on a 30 amp breaker, or keep the 12 gauge/20 amp and go with a small 1500w 19 gallon hot water heater since it is supplying only the kitchen and laundry and not the bathrooms.

What I am trying to figure out is if I am on the right track with the 1500w 19 gallon and if it will have the recovery needed for peak useage.

I have a plumber coming in this Friday evening to give a bid and want to have an idea what I need before hand.

Thanks ... appreciate any and all thoughts.

This message has been edited. Last edited by: old dino,

Simplest thing is to put 110 volt elements in a new 30 or 40 gallon heater.

Can't answer your electrical questions, but 19 gal should be fine for a dishwasher and washing machine. Unless of course the whole family comes home from a hike in the rain and mud to start washing clothes and ready to make dinner but y'all didn't do the dishes before you left so you need to run both overtime, at the same time. Electric cost difference insignificant heating 50gal vs 19gal. Small enough, get a 50 if the cost for the bigger one isn't insurmountable. Plus, like most things, will be grateful in the long run for having gone big.

I’d go with the smaller tank for the kitchen side of the house...less work, and I’d think it could handle the sink and dishwasher only.

Some good thoughts here ... has me thinking.

Doing the math (Ohm's Law): Watts / Volts = Amps

If I find a tank that is 20 to 30 gallons with a 3800 watt element, then with a result of 15.83 amps should be fine with the 240 volts on the 12 gauge wire and 20 amp double pole breaker.

At least I am getting an idea, and will be able to talk with the plumber on Friday.

19 gallons should be plenty for that, unless someone just leaves the sink running non stop.

quote:

Originally posted by jimmy123x:
19 gallons should be plenty for that, unless someone just leaves the sink running non stop.

I was thinking the same thing, and mostly when using the clothes washer it would be either warm or cold ... can not think of the last time we used hot to wash clothes.

quote:

Originally posted by old dino:

Doing the math (Ohm's Law): Watts / Volts = Amps

If I find a tank that is 20 to 30 gallons with a 3800 watt element, then with a result of 15.83 amps should be fine with the 240 volts on the 12 gauge wire and 20 amp double pole breaker.

Just keep in mind, heating loads are to be no more than 80% capacity.
20 amp breaker, 16 amp load.

quote:

Originally posted by old dino:

quote:

Originally posted by jimmy123x:
19 gallons should be plenty for that, unless someone just leaves the sink running non stop.

I was thinking the same thing, and mostly when using the clothes washer it would be either warm or cold ... can not think of the last time we used hot to wash clothes.

Another option is a bigger hot water heater and just putting lower wattage heating elements in it to match the wiring and breaker size.

Impressive or is SF slacking, 8 replies and not one mentioning that it's a water heater, not a "hot" water heater....

Imagine the smaller tank would work well, maybe even a tankless water heater for the kitchen/wash, we rarely wash with hot water anymore, run a tankless for the whole house.

If you have NG or LP then one of those would be good to use to reduce the electric power demand, otherwise an electric tankless might be a good solution.

Nobody wants to be accused of being a pedant. Never go full pedant.

Why would you want to heat hot water?

quote:

Originally posted by HRK:
Impressive or is SF slacking, 8 replies and not one mentioning that it's a water heater, not a "hot" water heater....

Imagine the smaller tank would work well, maybe even a tankless water heater for the kitchen/wash, we rarely wash with hot water anymore, run a tankless for the whole house.

If you have NG or LP then one of those would be good to use to reduce the electric power demand, otherwise an electric tankless might be a good solution.

I have seen both references used one way or the other in residential, commercial and retail settings.

Have natural gas available at this location, so that is a possibility.

The electric tankless is not a good solution in my situation as described in my original post regarding wiring and breaker. Electric tankless will be way outside of my electrical requirements ... and the reason/purpose of this thread.

quote:

Originally posted by Flash-LB:
Why would you want to heat hot water?

To make it hotter.

quote:

Originally posted by 1967Goat:

quote:

Originally posted by Flash-LB:
Why would you want to heat hot water?

To make it hotter.

Took the words out of my mouth ... !

quote:

Originally posted by old dino:
Some good thoughts here ... has me thinking.

Doing the math (Ohm's Law): Watts / Volts = Amps

If I find a tank that is 20 to 30 gallons with a 3800 watt element, then with a result of 15.83 amps should be fine with the 240 volts on the 12 gauge wire and 20 amp double pole breaker.

At least I am getting an idea, and will be able to talk with the plumber on Friday.

A plumber will install to code - that means a 30A breaker on 10ga wire

Local codes should be met. Generally a 3800 watt water heater is good for a 12/2 wire and a 20 amp 2 pole breaker. Standard 4500 watt water heaters go on a 10/2 wire and a 30 amp 2 pole breaker. Some locations are now requiring a 10/2 wire with a 25 amp 2 pole breaker for a standard water heater.

old dino I think you are on the right track.

quote:

Originally posted by sig operator:
Local codes should be met. Generally a 3800 watt water heater is good for a 12/2 wire and a 20 amp 2 pole breaker. Standard 4500 watt water heaters go on a 10/2 wire and a 30 amp 2 pole breaker. Some locations are now requiring a 10/2 wire with a 25 amp 2 pole breaker for a standard water heater.

old dino I think you are on the right track.

Thank you sir. Plumber was out yesterday and we talked about the wiring and water heater size. I will know more on Monday when I get his bid.

Will be for sure done to code ...

quote:

Originally posted by old dino:

quote:

Originally posted by HRK:
Impressive or is SF slacking, 8 replies and not one mentioning that it's a water heater, not a "hot" water heater....

Imagine the smaller tank would work well, maybe even a tankless water heater for the kitchen/wash, we rarely wash with hot water anymore, run a tankless for the whole house.

If you have NG or LP then one of those would be good to use to reduce the electric power demand, otherwise an electric tankless might be a good solution.

I have seen both references used one way or the other in residential, commercial and retail settings.

Have natural gas available at this location, so that is a possibility.

The electric tankless is not a good solution in my situation as described in my original post regarding wiring and breaker. Electric tankless will be way outside of my electrical requirements ... and the reason/purpose of this thread.

Natural gas tankless would be an excellent solution if your current water heater is on an exterior wall. You can mount the rinnae outside on the exterior wall, just need supply and return water lines plumbed through the wall to it and a little electric which you have right there also. IF, it's on an exterior wall of the house....easy to go right through the wall.

Was suppose to get bid last Monday ... called this morning Friday asking when may receive the bid.
Told estimator is behind, and had a wedding event this weekend, but will get bid out this evening.


This is the bid I just got :

Install and supply electric hot water tank $1300

Install and supply washer box and clean up of water pipe next to hot water tank $550

The clean up of water pipe was removal of a four foot length of galv pipe that is not being used and uncapped, installing a frost-free outside faucet that is supplied next to the water heater tank and replace the old gate valve to the faucet with a new valve.

I feel this bid was rushed just to get it out the door ... and it lacks details on what is being done as well as what is the make and model of the water heater.

Thoughts ?