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I just purchased a new build house from a guy in North MS. The drawings show 2 hot water heaters on the plans, but the builder only put one 50 gallon tank in place. I went round and round with him about it and he swears its enough, but the house has 3 bathrooms and I have 3 kids. No way it will be enough. He wanted to charge me a stupid amount of money to add another tank so I passed.

I don't have access to natural gas in the area and I'm not going to run any propane out there. So do any of you have any experience with electric tankless water heaters? Do they actually heat water up fast enough like the gas ones do?

You could be in a little bit of a pickle. To go to two flash heaters via gas or propane you may have to upgrade size of gas lines, regulators, etc. this could be a big job after the fact.

I have no info on electric flash heaters. I'm sure they exist. I just don't know anything about them. I've always "heard" they don't work as well as gas.

I'm thinking your cheapest way out now would be to add an electric tank near the other tank.

I'd suggest you talk to the plumber who did the work and get him to give you better info. I don't necessarily think that's adequate, I'm just saying

For what it's worth, many houses that size that I worked in only have one tank.

I have a electric tankless and I love it. We were able to reclaim a nice chunk of closet space with the swap. Mine takes two 30A 220v circuits. That was the hardest part of the install was the electrical.
Yes, it will increase your electric bill some, but not much.
One thing I never really considered was the degree to which the ground (incoming) water temp is going to play into the outgoing temp. Week to week, you probably wont have the "same knob setting" in the shower. We could lower the temp in the summer and raise it in the winter to compensate for the change, but we just adjust the shower knobs as needed.
The only other knock on ours is that the internals are all 1/2 pipe. And I had already plumbed everything all the way though to the shower in 3/4. So I have a pressure differential that I have to play with. 3/4 to 1/2 back to 3/4 messes up your water pressure a good bit. But it is not an issue, just something I know I have to wait on to balance out before I get in the shower.

My dad is a builder in the Jackson area and he pretty much only uses tankless water heaters now. I'm not sure which brand electric he uses, but they work great.

teul2 wrote:I have a electric tankless and I love it. We were able to reclaim a nice chunk of closet space with the swap. Mine takes two 30A 220v circuits. That was the hardest part of the install was the electrical.
Yes, it will increase your electric bill some, but not much.
One thing I never really considered was the degree to which the ground (incoming) water temp is going to play into the outgoing temp. Week to week, you probably wont have the "same knob setting" in the shower. We could lower the temp in the summer and raise it in the winter to compensate for the change, but we just adjust the shower knobs as needed.
The only other knock on ours is that the internals are all 1/2 pipe. And I had already plumbed everything all the way though to the shower in 3/4. So I have a pressure differential that I have to play with. 3/4 to 1/2 back to 3/4 messes up your water pressure a good bit. But it is not an issue, just something I know I have to wait on to balance out before I get in the shower.

couple questions for your post.
How far is your heater from the farthest outlet (tub/shower/sink)? How long does it take for the hot water to make it out at that farthest point?
When you say electric bill increased, I thought one of the selling features was the utility cost would go down from not having it heat water 24/7?
Ground water temperature change I can understand, but is the temperature difference because cold water doesn't heat up fast enough through the system? Does it still reach the temperature you have the thermostat set to?

Test the hardness of your water before you install a tankless water heater. We didn't before we installed ours at the camp in Arkansas. $700 for the heater and another $1500 later we've had to install a filter system and water softener kit.

fireplug wrote:How far is your heater from the farthest outlet (tub/shower/sink)? How long does it take for the hot water to make it out at that farthest point?

The shower is 20ft maybe. But through the pipes, that's probably closer to 40ft.
You can't judge time on mine due to my pipe size issue I mentioned before (or my reluctance to pull out all the 3/4 and change it to 1/2).But like I said, my pipes are messed up, so when I turn on the cold, I have to wait for those pressures to equalize to get in the shower. And the pressure differences between my shower and heater delay all of that. I'll say right now, 10 seconds of just the hot on and it is ready. In the winter, 20 seconds tops. Probably 10+ more seconds for the cold to equalize between them when I turn it on.
This pressure stuff sounds really crappy when I type it all out. My plumber dad is rolling in his grave right now.

fireplug wrote:When you say electric bill increased, I thought one of the selling features was the utility cost would go down from not having it heat water 24/7?

It may have increased $10 or $15. nothing major. But, when we did this install, we also did a major bathroom remodel. 100% new room studs out. So I can not truly discern the water heater cost from the 50-11 other electrical additions (8 can lights, 2 light sconces, heated tile floor, etc).

fireplug wrote:Ground water temperature change I can understand, but is the temperature difference because cold water doesn't heat up fast enough through the system? Does it still reach the temperature you have the thermostat set to?

In the dead of winter, when the incoming water temp is in the 30s and low 40s, I'd say no, it doesn't get to the 115 degrees we have it set for. It gets plenty hot, just not as hot as it is in the summer. But, we just use less cold and we are all good. The felt pressure at the shower head doesn't change.

There is no comparison once you have tankless, especially if you have girls. You should try and put it in a central spot at your house to avoid wait times for hot water but most put it on one end or another and I would rather wait for hot water than run out.