Space Zoo Patrol – Electric Tankless Water Heaters

By Frank Stiebel, President, Stiebel Eltron
 

1. Background

• What is this technology called?

Tankless electric water heating (also sometimes called electric on-demand water heating).

• How does it work?

Instead of using a tank to accumulate hot water that is heated slowly the tankless unit heats the water as it is flowing through the unit.  The unit does not have a tank as the name says.  In a whole house application a larger electrical service entrance is needed in order to be able to heat the water quickly.  This means a 200amp 240V is needed for the most common whole house tankless electric water heater,  which is the 24 KW unit.  However,  a 200 amp service entrance is becoming the norm.

• Who invented it? And when and where?

Tankless gas water heaters were invented in 1889. Tankless electric water heaters were invented in 1929 by Stiebel-Eltron in Germany.

2. Advantages

• What are the environmental advantages?

By eliminating the tank you eliminate the stand-by losses associated with it.  This results in a lower energy consumption compared to a tank type heater over a period of time and you can supply less electricity.

• What are the life cycle financial advantages?

Electric tankless water heaters are 24-34% more efficient than traditional storage tank water heaters (US DOE), thus saving hundreds of dollars per year in electricity. Tank type heaters have a large internal surface area as it holds the water which has to be protected from corrosion.  Almost all tank type water heaters have a steel tank so it is a big task to keep it from corroding.  This is usually done with glass lining.  The wetted surface areas in a tankless heaters are much smaller by comparison and they are typically made out of copper,  stainless steel, or high tech plastics so they tend to last longer, which saves on maintenance costs.

• What jobs are created?

There are jobs created in the design,  manufacturing, selling, and installation of the tankless units.

3. Energy Production

• How efficient is this technology? (percentage efficiency)

Nearly 98-99% of the energy content in the electricity is converted to heat in the water.

• How many units are needed for 1 house?

One can either have one large unit per house (with a conventional tree type distribution system) or have multiple units where ever hot water is drawn.

• What percentage of homes in the US use this technology today?

Currently, less than 10% of homes in the US use this technology.

• What percentage of homes in the US could use this technology in the future?

In the future, this technology could be installed in 100% of houses and buildings.

• What geographical areas can this be used in?

The benefits of this technology are useful no matter what geographic area they are used in.

4. Engineering / Mechanical
   • How is it manufactured?

The factory assembles water pipes, electric heating elements, power cords, and a box to hold all the parts.

• • What maintenance is required?

In hard water conditions we recommend that the tankless heater is flushed once a year with a deliming fluid such as vinegar or similar.  One can also install a water softening device that is in the water line before the water gets to the tankless unit.

5. Education
   • • What classes should I take in school to work on this technology?

Electrical engineering, mechanical engineering, and physics.

6. Pictures 

7. Links

Stiebel-Eltron-USA stiebel-eltron-usa.com