Energy saving water heater shower

Posted on 2015-01-17
Medium Priority
Last Modified: 2015-01-21


I'm looking at the above models, one is ECO-11 & the other ECO-27.

Which of the 2 could work in UK?  I'm in a commonwealth country which uses UK's standard

Which of the 2 saves more energy?  

Anyone tried them before & do they really save up to 60% (I'll be happy if it saves 50%) energy ?
Question by:sunhux
LVL 34

Assisted Solution

by:Mike Eghtebas
Mike Eghtebas earned 680 total points
ID: 40555322
"TANKLESS" compared to "Storage Type" (even if it is insulated) looses heat (energy) during 24/day. So does the piping from the tank to shower, kitchen sink, etc. In this sense, it is bound to save energy.

But, if you are rich and want to fill a bathtub very quickly, "Tank Type" is a better choice.
LVL 27

Assisted Solution

d-glitch earned 520 total points
ID: 40555350
The next time you take a shower, stop in the middle and hold a bucket under the shower head for 1 or 2 precisely timed minutes and measure the amount of water you like to have in a shower.
Also measure the temperature of unheated water as it comes into your home.  
You need this info to specify the shize heater you need.

A conventional water heater (gas, oil, or electric with a tank) is very wasteful.  

Assume you have a 25 gallon tank and take one 20 gallon shower every day.   You are happy.  But after your shower, the water heater heats up another tank full of water, and keeps it hot all day.  The water in the tank and the pipes will cool down, even with the best insulation.  If you go away for a week, the water heater might turn on a dozen or more times for nothing.  All waste.

If you try to take two 20 gal showers in the morning with  a 25 gal tank, only the first customer will be happy.  If you get a 50 gal tank, you loses will double.

A tankless water heater does not save any money heating the water.  All of the savings come from eliminating the waste, which is real and significant.

The smaller unit you listed would not work for me.  The flow rate is low and my inlet water is too cold.

The larger unit would probably work, but please be aware that it takes an enormous amount of electricity.  You might need to upgrade your electrical service to handle it.  Talk to a local plumber and electrician.
LVL 50

Accepted Solution

dbrunton earned 800 total points
ID: 40555357
Which of the 2 could work in UK?  I'm in a commonwealth country which uses UK's standard

Either should work BUT check they comply with local plumbing and electrical regulations.  Also check with ECO as well.  You may be able to buy locally rather than from Amazon overseas.

Which of the 2 saves more energy?  

The ECO 27 as it does the whole house.  The ECO 11 is designed for small intermittent loads such as doing the hot water for the kitchen sink or the hot water for a washing machine.  The ECO 11 is not designed to support the whole house.  The ECO 11 is useful where hot water support is required a long distance from the hot water tank.  Yes, it will save power there but not much.

Anyone tried them before & do they really save up to 60% (I'll be happy if it saves 50%) energy?

The magic words are up to 60% and the answer is it depends. It depends on your present consumption routine/usage and your present house wiring and plumbing.  I suspect you won't get 50-60%.  For the ECO 27 you'll probably get 10% saving in power bill but you'll have to factor in costs for the plumber and electrician and the ECO unit as well.
LVL 34

Assisted Solution

by:Mike Eghtebas
Mike Eghtebas earned 680 total points
ID: 40555383
As mentioned by others, the energy saving comes from avoiding stand-by heat loss from:

1. Storage tank (with or without insulation),
2. Pipes (with or without insulation), and
3. Circulating pump (if one exists).

So, the manufacturer of the thankless water heater to justify 60% saving most likely assumes all 3  items above exists for typical insulated system and then compares with their own system. So, this saving may differ for you based on how your existing tank is protected from the outside weather and how apart your water heater is located from the point of use (piping length).  

Not to split hair here, but thankless water heater has faster rate of energy use compared to water heater. If so, then the third law of thermodynamic suggest that because of entropy rate, the storage water heater is doing more efficient heating. This will be a minor advantage of course.

Author Comment

ID: 40559682

Well I only need one for a bathroom to trial run to see how much it helps as our electrician has identified the
water heater as a top energy consumer beside the aircon.  The fact that it's 240Volt is what we are using in
our country but still worth to write to ECO

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