dealsecosmart 11 kw self modulating 2.14 gpm electric…

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vote-for14vote-against

This certainly won't work in PA, where the incoming water temperature averages between 40º and 50º.

Even if you live some place with warm enough incoming water (like the equator, maybe), this heater would need a 50 amp breaker at 240 volts. (11,000W / 240V = 45.8A) which is quite a lot of electricity. Many houses (including mine) couldn't provide an additional 50 amp breaker without installing a whole new service entrance panel (breaker box) and heavier entrance cable.

This is not your average afternoon DIY project !

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@crowbite sure, but if you're replacing an electric water heater, you're probably going to have a 50A breaker available from it.

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Also, Consumer Reports does not like these things at all. I was considering them when I built my house but after doing some research I opted for a traditional propane heated one.

The gist of the Consumer Reports article was that they have terrible reliability and need to be serviced yearly. Any money estimated money saved in heating costs was more than accounted for in maintenance. So get this if you want to save a little electricity/gas but spend more money over the life of the unit. (also they do not last as long as a traditional HWH).

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@crowbite: Use 2 in series :) that'll warm the water up alright.

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@matkyne: Thanks for posting the Consumer Reports info. I will look into their reviews. Interesting that the Amazon reviews were so much more positive. Frankly, I am not looking for one of these to replace my tank water heater, but to supplement it. Specifically, we want to have access to hot water outside for dog bathing, et al. We've looked into running a hose from our regular water heater to the patio, but that would be pretty cost-prohibitive because of its location. This particular tankless heater is not a high volume one, but would supply enough warm water for the outside chores without the need for hauling buckets out.

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@martinh:
No, that's not true. A typical home water heater is between 3.6kW and 4.5kW. They will run on a 20 amp circuit, or if you want to be overly conservative, a 25 amp circuit.

And since this heater requires twice the amperage, not only do you need a bigger breaker, you need to replace all the wiring between the breaker and the heater with a heavier gauge wire. So there goes a few hundred dollars more (minimum) for electrical upgrade, if your service entrance and breaker panel have enough extra capacity.

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@johnt007871:
Yes, actually that is true. It looks as if this provides about 50º temperature rise at the rated flow (120º output - 70º inlet). wo of them in series would give you perhaps 100º temperature rise, which would be more than adequate for 40º inlet temperature in the winter.

Unfortunately, two of these in series would require 100 amps worth of service at 240 volts, which is quite a lot. I'd bet that very few homes have that much excess capacity in their electrical entrance.

In theory, demand water heaters are a very good idea, especially if you locate them close to the needed outlet (i.e. bathroom or kitchen). You don't have heat loss from the tank or from long piping within the house.

Demand heaters are widely used in Europe. I'd guess that a lot of them use natural gas, rather than electricity, as a heat source. I have personally stayed in European homes that had them (gas fired) right in the bathroom. But getting that much heat from electricity is problematic.

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@crowbite: I'm an engineer. I never said it was practical :)

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@matkyne: The consumer reports article you linked was from 2008. Their tested units then were in the $800 - $1,100 range. This WOOT deal has a unit for $159. So... the economics have changed.

I will agree that the unit that I would consider purchasing now for my Colorado home would be Natural Gas heated, not electric We had that in Brazil, and the never ending hot water was fantastic!

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I can't speak for this particular brand, but comment #6 is correct with respect to consumer reports, but I have lived in Europe and I opted in even after the consumer report. Our house is three years old and we have two gas heaters. One a Jacuzzi and the other on the other side of the house, is a Bosch. Both work well on cold well water. Have to decalk every two years just to be safe. Really love the Jacuzzi gas heater, it's our primary.

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I just replaced an electric water heater that lasted 15 years and did a whole lot of research involving cost v. efficiency v. convenience. Electric tank less water heaters are at the very bottom when one considers these factors with one only a couple of exceptions to consider. In a vacation home without a gas option and only for occasional use and in a climate where the water temp never comes even close to freezing then and only then one of these might be considered. A whole house unit will need about 2 to 4 double pole breakers depending on kw output and extensive rewiring would be necessary in almost all homes. This one is a toy compared to the one needed for whole house water heating.

BTW, I went with a heat pump water heater and installed it myself.

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@belyndag: "we want to have access to hot water outside for dog bathing, etc,"

I wonder if these would work as a low-tech solution for you? I'm considering getting a couple to avoid turning on the oil-powered basement furnace/"boiler" just for a quick shower. (It heats water for the radiator system and also on demand for bathing, etc.) All accessible hot water pipes are insulated, but it still puts out considerable BTU's every time it ignites. Seems a damn shame to waste money and heat up my basement if I could enlist the broiling summer sun to do the work for me. Of course, a real solar water heater would be ideal, but that ain't happening ...

Sorry for the thread hijack!

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@zebraitis: "So... the economics have changed."

Not really. The cost of the unit has dropped, but the cost of water heating hasn't, nor has the cost of yearly maintenance fees (assuming you don't DIY).

These still aren't the most cost-effective way to deliver hot water to a full bathroom. The startup cost is cheaper, that's all.

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@ginawoot:
That plastic bag is a pretty marginal solution at best. It gives you only 5 gallons. Depending on outdoor temperature and sunlight, the water may be only marginally warm. And it's delivered at a relative trickle, not full pressure like in your house.

You're right, though... turning on a home heating system, just to heat domestic hot water in a heat exchanger tank, is very inefficient.

If your electrical entrance panel (fuse/breaker box) can handle it, you'd be better off installing a small electric water heater. There are some very small ones (7 - 10 gallons) intended for just bathroom sinks and/or mobile homes. Some of these even run on 120 volts, and don't require any special wiring. (Although you might get screwed by your local building codes.) They'd be far better than your oil-fired home heater, and, actually, ten gallons is just marginally enough for a quick shower.

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I have a tankless water heater in my home in Florida. It's a double coil that uses 2 40 amp breakers to provide enough hot water for the house regardless of how many faucets are being used. As for the energy costs, I have seen savings on my electric bill in the past year and a half that more than offset the cost of my unit (I paid $240).

Just because it needs a large amperage breaker doesn't mean it'll be drawing that much power. I tested my coils and they draw between 18 and 26 amps each, with a surge of 32.

However, note that these are kinda annoying to install, you can't have PVC running within 12-16 inches of the unit, and most local regulations require them to be installed by a contractor to be legal. The flow rate of my unit is a little under advertized, but I haven't seen any problems unless we're running the washing machine, dishwasher and shower at the same time. Don't be afraid of these units, just know your household water usage before you buy and filter your water.