[gp_wa]

I am getting close to being able to redesign my hot water system completely, and I am looking at electric tankless heaters to go along with a solar preheat system. I don't have gas at the house, so I'm treating that as not an option. I also would like a unit that will heat to at least 130, preferably 140. I figure if the faucet says "hot", it ought to produce hot water, damn it

I do have 200 amp service, and I seem to have arrived at < 100 amp unit. I plan to install a sub panel for the water heating system, so breakers and cabling and such are not an issue for me.

I am concerned about a couple things, and I am having trouble with some of the specifics of the various electric tankless units that are on the market.

I've seen some references to lights dimming sporadically and output temperature fluctuating. Does anybody know how these silly things work? Are they only able to turn individual elements on or off? That seems absurd.

Does anybody have experience with American Heat? In particular, the "Ultimate" whole house model...

http://www.americantanklesswaterheaters.com/

[chris75]

Your electric service may not be big enough, depending on your current calculated electrical load and your new added load, you may need a 320 amp service. This of course will not be an inexpensive upgrade. And yes, your lights are going to dim, your neighbors also if you share a transformer...


Best thing to do is more research and have someone do a new service calculation on your house with the new load and see where you stand.

[gp_wa]

Originally Posted by gp_wa

I've seen some references to lights dimming sporadically and output temperature fluctuating. Does anybody know how these silly things work? Are they only able to turn individual elements on or off? That seems absurd.

Does anybody have experience with American Heat? In particular, the "Ultimate" whole house model...

Bump...

Anybody here have any experience with electric tankless water heaters?

[chris75]

Guess you didn't believe me.

[gp_wa]

Originally Posted by chris75

Guess you didn't believe me.

What do you mean? You said my lights will dim and that I may need a larger service. I believe you.

That doesn't answer the questions I have, though. I'm not wondering IF a tankless will cause my lights to dim, I'm wondering about the "sporadic" part and how they actually work. If my shower is going fluctuate because the silly tankless unit cannot control the temperature accurately, I'm not sure I'm even interested in one.

[Jeeper1970]

My understanding is that the electric elements can't heat the water fast enough as the water passes by, which is what causes the fluctuation in temperatures. If you live in a cooler climate, especially during the winter, you'll experience this more than if you live in a warmer climate.

Because of the draw that it pulls on your electric, hence the dimming, in the end it doesn't save much on the electric bill.

I've read a couple articles that suggested if you have no access to gas heat, just go with a new, more efficient tank water heater.

[Marvin Gardens]

I don't like electric tankless water heaters. To slow and take a lot of electricity to run.

If you are going with solar hot water then just get an electric solar exchanger that will back up your solar when needed. Get a large one like a 120.

[clasact]

The tank itself will not control the temp,normally they have a knob to turn it from high to low.I have two small Titan units run together ( only due to I have not finished the rest of the house) one tank will raise the temp about 50 deg two as in my case will raise the incoming temp above 100 deg.Although mine normally don't come on together only sometimes.The light due dim sometimes but I am also in the middle of a upgrade that has been slowed due to economics.The tamp of the water in the shower is controlled by the mixer and we don't have to turn it much to get hot water(real hot).The difference between my gas bill that used to heat my water and the electric that heats is now was pretty substantial (gas was much higher).The element in the unit are activated as the water pressure hits it as stays on till you either shut it off or turn the mixer to cold.I know many on here will tell me I wrong for having this system (many have already) but I will never put another tank system in my home.I love these things ,you never run out of hot water ,they were easy to install,they don't take much room at all,and I save money with them.I dont know if this really answers what you need or not

[Marvin Gardens]

Just so you know that an electric tankless takes a lot of electricity and is not going to perform like a gas tankless.

[gp_wa]

I see I forgot to mention something important. I plan to have a back up heating element in the solar preheat tank, which will maintain a minimum temperature if at least 90* (adjustable upward if needed) regardless of available solar heat. That means the tankless would only need to provide a 50* rise maximum under normal conditions, and none at all during sunny periods.

[clasact]

that is correct since you do not set the temp on the tankless to any set temp and at max the small ones I have raise it 50 deg