[Greenbuilding] Opinions on electric tankless HW heaters?
Bob Waldrop
bwaldrop at cox.net
Thu Apr 21 11:46:36 CDT 2011
FWIW, turning the hot water off and on is not a hard task. It took me about a month to get the hang of it so there was generally always hot water, and after about 6 months, we got to where we didn’t care if there was hot water instantly all the time 24/7/365. It’s so integrated into the household tasks that it seems like I have always done it this way.
Of course, I should also say that this was preceded by a whole year without a hot water heater at all, lol, so that did a lot for demand destruction and also made having a hot water heater seem like an unimaginable luxury. I don’t advocate that people do the one year without hot water thing, lol. Actually, we had plenty of hot water, we just used even more redneck solutions such as heating water on a sunny day in a black painted bucket or in a garden hose. it did break our addiction to long (e.g. 15 minute) hot showers, which also saved money on the water bill.
Several people here locally have done this, after a local educational station did a documentary about our house, as it is a simple and easy and not very expensive thing to do for people with existing electric water heaters. We installed ours as part of a whole house rewiring, but I hear from friends that it costs about $200 to have an electrician come out and install a switch.
Bob Waldrop, Okie City
From: Steven Tjiang
Sent: Thursday, April 21, 2011 8:32 AM
To: Green Building
Cc: Greenbuilding at bioenergylists.org
Subject: Re: [Greenbuilding] Opinions on electric tankless HW heaters?
This is getting off-topic.
After many years I learn to pick my battles at home. I won the "hanging up the laundry on a clothesline" battle which will save more energy than some other possible behavior modifications.
But generally....we need to learn to pick our battles when it comes to saving energy as a society. Hot water systems that saves energy and provide the same level of comfort w/o user intervention will get wider adoption and hence ultimately save more energy in total, than something that might individually save more energy but receive little adoption.
Having said that I'm going to bike to work now.
P.S. But Bob I admire your dedication to turning your hot water heater off and on. I would do likewise if I could.
---- Steve (KZ6LSD)
On Thu, Apr 21, 2011 at 4:35 AM, Bob Waldrop <bwaldrop at cox.net> wrote:
It is true that I am a confirmed bachelor, and that in fact people often tell me, “Bob, if you had a wife, she would not let you do that,” (“that” being whatever my latest low tech red neck energy conservation scheme might be.) Having said that, it does take some amount of internal discipline to remember to turn the switch OFF once it has been turned on, and also to not necessarily turn it ON every time you need hot water, this is true for both males and females. Over the last six years, various roommates have come and gone (the population here waxes and wanes between 2 and 6), and each time with the newbies there is a bump up in consumption for a couple of months while they get used to the drill.
Bob Waldrop, OKC
From: Steven Tjiang
Sent: Wednesday, April 20, 2011 11:33 PM
To: Green Building
Cc: Greenbuilding at bioenergylists.org
Subject: Re: [Greenbuilding] Opinions on electric tankless HW heaters?
Bob
Your strategy would save energy and cost less and certainly in the spirit of "demand reduction". It, however, would not pass the spousal acceptance test.
---- Steve (KZ6LSD)
On Wed, Apr 20, 2011 at 8:36 PM, Bob Waldrop <bwaldrop at cox.net> wrote:
I think you can get the same effect, for a lot less money, by simply installing a regular tank electric water heater and putting an on-off switch on it, and be frugal in your use of hot water. (We are the masters of the three minute shower.) When our tank has cooled to ambient, and I flip the switch, within about 10 minutes I get a stream of hot water at the tub or the kitchen sink.
Bob Waldrop, Okie City
From: Steven Tjiang
Sent: Wednesday, April 20, 2011 1:27 PM
To: Green Building
Cc: Greenbuilding at bioenergylists.org
Subject: Re: [Greenbuilding] Opinions on electric tankless HW heaters?
Depending on the source of generation, heat pump water heaters have roughly the same carbon footprint as gas water heater. However if you power using electricity from renewables (wind) HPWH is significantly better. My local utility offers the wind option, so I went with the HPWH with solar preheat. Even if one were to use a Drain heat recovery, HPWH is still the best alternative.
Having said that, demand reduction still comes first.
---- Steve (KZ6LSD)
On Wed, Apr 20, 2011 at 11:04 AM, Frank Tettemer <frank at livingsol.com> wrote:
Hi All,
I can't vouch for Nick's idea that they only manufacture 13KW tank-less hot water heaters. I think that the manufacturers would certainly provide electric tank-less heaters of all electrical load sizes, simply because there would be a demand for lighter-duty models, and Somebody is going to fill that market. However,
That doesn't mean that a light-weight tank-less heater would provide a satisfactory supply of hot water. And certainly anyone who has traveled South of the border, to various Carribean countries has experienced those light-duty electric shower heaters, plugged into an overhead electrical recepticle, just out of reach of the shower curtain. (I'm not promoting these models for US or Can. use, however.)
What I do think is entirely wrong,
is the idea that an electric hot water heater, of any make or model, could possibly be considered environmentally friendly. It's just way too big of a stretch in reality.
Consider that a typical household of four would probably spend about $30 to $40 per month on heating hot water. Either system, tank-less or tank.
This is equal to about 400 Kwh, at the household's electrical meter base.
This is also equal to about 1,300 Kwh of comparable fuel, being burnt at the coal plant, or nuked at the nuke plant.
(As we know, the accumulated losses, from conversion of fuel to heat, conversion of heat to steam, conversion of steam to rotary motion, conversion of motion to electrical current, and line losses from transmission all add up to a factor of about 3.25 to 1. This is a phenomena that is hard to accept, but even more impossible to ignore, while designing appropriate technologies in an energy efficient home.
Yes, Carmine, if we only look at the almighty dollar, and compare costs of various methods of heating domestic hot water, or heating hot water for distribution into household heating, the electric devices all end up costing less to purchase and to operate, in the initial assessment.
Giving regard to overall embodied energy of construction of the domestic hot water system, and associated energy of electrical production and transmission over a decade or two, however, the question arises as to how this all pans out over the coming decade or two. Looking at a comparison of economics, via using the dollar as the unit of measure is way too short-sighted. It is misleading and hides the truth.
In my humble opinion, and in my home design practice, I have not specified any greater electrical use in a home that can be produced near to the location of the home. As well, the PV array and/or wind turbine associated with the home's electrical production really must be capped at a small enough investment, (both dollars and embodied energy), that this system is also not a burden to the planet. In other words, designing a 10KW PV system, plus a 10Kw wind turbine, for one single household, is to me a pathetically privileged idea, and un-necessary exhibition of wealth, and simply represents a too large footprint. I have built many homes over the years, on of off grid, that operate on 3 to 5 Kwh per day, total electrical loads, simply to avoid the burden to the grid and to the planet in general.
If the average Canadian household uses 29 to 32 Kwh per day, then a home that uses only 5 Kwh per day is living more lightly. And this difference, when converted to fuel consumption for the electricity used, represents over 2,000 units of fuel equivalency.
This represents a savings upon the grid, and lightens it's load.
Nearly any other fuel will have a lighter impact than electricity for hot water. And I'm not even taking nuke meltdowns, like in Japan, into the equation. If we add that level of environmental toxicity to the balance sheet, avoiding electrical on-demand hot water heaters is a no brainer.
If we are serious about discussing economic and environmental waste, let's first consider simply living with less expectations, way less over-all consumption of all goods, accepting and surrendering to the uncomfortable fact that this planet cannot support our North American "needs" any longer, without these "needs" being clearly labeled as privilege and greed.
I believe that it is misleading people with advice that switching from one fossil fuel to another is going to "improve" the environment. There is no "better" fossil fuel, just as there is no better way to continue to consume goods at the rate of most middle class households.
Our best fuel is a leap of faith around finding that living with way less is way better.
Frank Tettemer
Frank Tettemer
Living Sol ~ Building and Design
www.livingsol.com
613 756 3884
.............................................................................................................................................
Nick: Please stop misleading people with your erroneous advice. We all know your prejudice against both tank-less heaters & tank-less drain water heat recovery systems that can deliver Energy Factors well above that offered by the kinds of water heaters you promote.
Carmine
gfxechnology.com
------------------------------------------------------------------------
From: npyner at tig.com.au
To: greenbuilding at lists.bioenergylists.org
Date: Tue, 19 Apr 2011 09:37:24 +1000
Subject: Re: [Greenbuilding] Opinions on electric tankless HW heaters?
Instant electric is usually the last choice on economic and environmental grounds.
I doubt that Rheem would make them. Another manufacturer that does is Stiebel Eltron. They have some pretty sophisticated models but they are expensive and probably no more efficient than their simpler ones.
Even a small instant electric will take about 13kW, so retrofitting one may call for some expensive wiring.
Nick Pyner
Dee Why NSW
-----Original Message-----
*On Behalf Of *Matt
I have clients who might be ideal candidates for a tankless hw heater. They don't have natural gas in their home. I have installed gas tankless, but don't have any experience with electric tankless heaters. I will need to size one for a family of two to four.
Any opinions out there? Bosch? Rinnai? Rheem?...
--
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