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  1. #1
    Join Date
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    Default Tankless Electric Water Heater

    Our water heater is showing serious signs of slowing down. I had planned to replace it with an electric tankless model water heater I read about on Ebay (Stiebel-Eltron - Tempra 36 -36 KW?).

    I spoke to a friend who said there had been a lot of fires started by the whole-house electric tankless heaters, but the gas ones were better. I react to gas, so it would have to be placed outside (and we're currently all electric)and not in the laundry area where the current hw tank and the breaker box is located.

    But, I've searched on the web and can find no reference to fires started by these electric water heaters, only some by the inferior wiring used to install some.

    Anyone have experience with any of this? I'd like to avoid the fire ;-).
    Sara

  2. #2
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    Jun 2007
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    NorthWest Florida
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    Default Re: Tankless Electric Water Heater

    I don't know of any issues when properly installed. You'll need an electrician to wire it, as any county I know of would require a certified install for anything of this magnitude. A 36kW is going to need some serious wiring, they may have to run a new run from the exterior house feed (or maybe even add another wire from the poles/underground junctions out at the road) to a separate breaker box just for the heater.

    If you're really paranoid about a fire, see if a plumbing company is willing to mount the breaker box and water heater to the wall with a fire shield of some type between them (mineral wool sheeting, cement board, etc).

    I'd be more worried about fire from a gas heater than an electric, as long as the electric is properly installed with the right gauge wire and quality breakers.
    Tom Stangl
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  3. #3
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    Default Re: Tankless Electric Water Heater

    Thanks, Tom! I plan to have an electrician/plumber do the work - and the person who said this about the fires is a plumber.

    I thought it shouldn't take more than the stove.... which is a double 40 (but that's what the current water heater is too), or the heater which is a double with a 90 on it.... but that's amps, not KW, right? Running new wire would be easy since it would be within a few feet of the breaker box, which has many open slots for breakers. Maybe I don't need such a large one for a 1500 sf house with 2-1/2 baths? We just want hot water available anytime we need it.

    I couldn't find anything about the units themselves being faulty in this way as he seemed to think they were. Yes, I would think gas would be more of a problem too.

    Does anyone use a tankless water heater? Are you happy with it?

    Sara

  4. #4
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    Default Re: Tankless Electric Water Heater

    Quote Originally Posted by 2sara View Post
    Thanks, Tom! I plan to have an electrician/plumber do the work - and the person who said this about the fires is a plumber.

    I thought it shouldn't take more than the stove.... which is a double 40 (but that's what the current water heater is too), or the heater which is a double with a 90 on it.... but that's amps, not KW, right? Running new wire would be easy since it would be within a few feet of the breaker box, which has many open slots for breakers. Maybe I don't need such a large one for a 1500 sf house with 2-1/2 baths? We just want hot water available anytime we need it.

    I couldn't find anything about the units themselves being faulty in this way as he seemed to think they were. Yes, I would think gas would be more of a problem too.

    Does anyone use a tankless water heater? Are you happy with it?

    Sara
    I am investigating installing one in my 2000 sqft 3BR/2B house. Looking at the Bosch units available at Lowes, I can probably get away with the AE-115, as we don't run more than 1 shower at a time, and wash clothes in the evenings when rates are lower. The AE-115 essentially can run 1 shower, it is rated at 2.6gpm. It requires 2 40A 220V breakers and a 200A service to the house. The AE-125 is rated at 4gpm, not quite 2 showers simultaneously. It requires 3 40A 220V breakers and a 200A service to the house. I plan on checking to see if I need another cable run to the house, or whether I can have a new breaker box tapped to the current service, placing it next to the heater.

    There may be larger electric ones out there to handle 2-3 showers and your dishwasher at the same time, but of course they're going to need some major wiring to them.

    http://www.itankless.com/index.cfm?p...facturer=Bosch has a nice table showing the temp rise for different gpms. Googling on "+Bosch +AE-115" (or 125) should give you some good info to research.
    Tom Stangl
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  5. #5
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    Default Re: Tankless Electric Water Heater

    I have hotwater heating system in my floors.
    Can I use the tanks less water heater to take over from my 50 gallon hot water heater which is electric.
    Or don`t you people recomened this trade off. The water heater is 15 years old and will need replcement.

  6. #6
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    Pittsburgh Pa.
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    Default Re: Tankless Electric Water Heater

    I have a Bosch from Lowes. I just wish I would have installed it years ago! Mine is gas with a hydro ignition system.(no standing pilot) People I have talked to about eletric units say the same thing.."They spin the meter like crazy" Money wise the gas unit is the way to go...Ziggy

  7. #7
    Join Date
    Jun 2007
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    Default Re: Tankless Electric Water Heater

    Quote Originally Posted by Ziggy View Post
    I have a Bosch from Lowes. I just wish I would have installed it years ago! Mine is gas with a hydro ignition system.(no standing pilot) People I have talked to about eletric units say the same thing.."They spin the meter like crazy" Money wise the gas unit is the way to go...Ziggy
    As long as you have NG available, they can be more advantageous. But NG prices seem to fluctuate a lot more than electric (even though a lot of elec utils use NG for their plants), so looking into the future, the electric could be a better alternative even if you have NG service.

    For those of us in FL, though, note that if you get an electric tankless, you need to consider that a portable generator isn't going to cut it for hot water after hurricanes. You'll need a whole house NG/propane generator to handle the large load of an electric tankless (and a pretty large whole house generator at that).
    Tom Stangl
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  8. #8
    Join Date
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    NorthWest Florida
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    Default Re: Tankless Electric Water Heater

    Quote Originally Posted by manin2boat2 View Post
    I have hotwater heating system in my floors.
    Can I use the tanks less water heater to take over from my 50 gallon hot water heater which is electric.
    Or don`t you people recomened this trade off. The water heater is 15 years old and will need replcement.
    I would NOT recommend an electric tankless for radiant heating, as it is going to run almost constantly, and tankless units use a LOT of electricity (of course, they're only supposed to use it for a short time - i.e. using lots for 15min during a shower, but off for most of the rest of the day). And a gas tankless will use a lot of gas to keep the radiant system running.

    You are better off buying the most efficient tank heater you can find when feeding a radiant system. Or even consider splitting your system, running 2 tank heaters, one for the radiant heating, one for everything else. That way, you can use a smaller tank on both circuits, and use a timer control for the tank that feeds showers, etc, so that it heats up the water early morning in time for showers, but shuts down for most of the day.
    Tom Stangl
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  9. #9
    Alfetta159 Guest

    Default Re: Tankless Electric Water Heater

    I've looked into electric tankless, and like the previous post says, you want to make sure that your house is already wired for a couple hundred amps. Also, the electric tankless might not be that efficient energy-cost wise. That is it will probably cost more money in energy costs to run an electric versus gas. Unfortunately gas is usually cheaper to heat things be it water, your house, ovens or clothes dryers. I realize that the cost of gas has been up lately, but it is really expensive to wire your old house for 200 A.

    On the other hand, if you get a high capacity, gas powered tankless, often the gas line has to be enlarged to handle the power needed as well.

    (Rant alert!)

    I would like very much to go solar in my house, however, my old house needs a lot of updating like getting rid of the knob & tube wiring and the galvanized plumbing. And some modern insulation would be nice.

    I would then consider solar, both electric and thermal. I would also consider plumbing the light hot water fixtures (e.g. sinks) and heavy fixtures (e.g. tubs, showers, washing machine, dishwasher) separately so I could have the option of an electric light duty tankless and a gas powered heavy duty tankless or just go photo thermal on one or the other fixture zones. A couple tankless heaters would take a bit of room, but so do the old tank jobs. And yes, I realize a solar system is not going to have enough power for a tankless heater, but it could supply enough energy for a small one.

    It would take a bit of analysis to set up a system that uses as much electricity as I generate with solar so that I could go w/ gas for the rest of the heating energy that I need. I’m just not there yet.

  10. #10
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    Default Re: Tankless Electric Water Heater

    Quote Originally Posted by Alfetta159 View Post
    I would then consider solar, both electric and thermal. I would also consider plumbing the light hot water fixtures (e.g. sinks) and heavy fixtures (e.g. tubs, showers, washing machine, dishwasher) separately so I could have the option of an electric light duty tankless and a gas powered heavy duty tankless or just go photo thermal on one or the other fixture zones. A couple tankless heaters would take a bit of room, but so do the old tank jobs. And yes, I realize a solar system is not going to have enough power for a tankless heater, but it could supply enough energy for a small one.
    A properly sized thermal solar hot water system, with a properly-sized highly insulated tank, will give you all the hot water you need without involving electricity at all. At least in many areas of the US - Minnesotans may not apply ;-)

    Lots of Floridians with pools use thermal solar heaters to heat the pools, so heating the small amount of water for a house can be quite easy/economical when you look at the total cost over the life of the system.
    Tom Stangl
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