Electric shower heater (C) D Friedman A PuentesGuide to Electric Shower Heads - Instant Hot Showers
Shower Water Heaters

  • ELECTRIC SHOWER HEATERS - CONTENTS: Point of use electric shower heaters: Dur-o-Matic, Marey, Steibel Eltron, other hot water brands.Tankless water heaters = demand water heaters = instantaneous water heaters. Detailed explanation of how tankless hot water heaters work, what they cost, what are their operating characteristics, pro's and con's.
  • POST a QUESTION or READ FAQs about electric shower water heater heads: choices, installation, performance, safety
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Electric shower heaters: this article explains the operating characteristics of electric shower heaters, also called instant water heaters or "on demand" water heaters for point of use at shower heads.

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A Guide to Electric Shower Water Heaters

Electric shower heater (C) D Friedman A PuentesAn instant hot water point of use system like the shower heaters we show here are a very different approach to making hot water for bathing than the tankless water heaters discussed above.

These electric shower heads work where the incoming water temperature is pretty high to start and where the water flow rate is modest.

Electric shower water heaters are typically used where a central hot water heater is not installed. The heater is installed directly on the shower water piping at the location where a conventional shower head would otherwise be found.

Several companies, including Dur-o-Matic and Marey (shown below) and Steibel Eltron produce point of use electric heaters such as the electric shower heaters shown here.

These electric point of use water heaters are typically installed in buildings where no water heater or hot water source has been provided.

When a sensor in the shower head detects water flowing, the electrical heating element turns on. An electrical element heats water as it enters and flows through the unit, drawing typically about 23 amps (when wired at 110V 2400 watts) or 13.5 amps (when wired at 220V 2900 watts).

The temperature of the hot water received depends on the flow rate through the heater.

Slower flow rate yields hotter water. Flow rates are limited, however, with a maximum water pressure of 2 gpm and a minimum water pressure (to activate the unit) of 0.83 gpm. The average water temperature increase across this range is 10-25 degF.

Marey electric shower heater (C) D Friedman A Puentes

That means that if the incoming water temperature is 42 deg.F. (northern U.S. and Canada) your hot shower might reach 67 deg.F. at the slowest flow rate of less than 1 gpm. Not a hot shower.

These point of use electric showers are intended to work in areas where the incoming water is already not very cold, such as the more tropical climate of Puerto Rico, where Duro-Matic is based.

The Mini Marey tankless shower heater (photo at left) is advertised for use in boats, cabins,campers, recreational vehicles (RV showers), mobile homes, apartments where no central water heater is provided.

Puentes, who inspected a large number of electric shower installations in Puerto Rico in 2009 reported that perhaps because these devices were installed in homes of people of limited means, many of them were simply turned off entirely in an effort to reduce the occupant's electrical bill.

We found the exposed electrical wiring at some of these point of use electric shower heaters disconcerting and a possible electrocution hazard, particularly where the wiring was not GFCI protected. Be sure that your electric shower heater is wired according to local and national electrical codes.

Question: how do I choose & set voltage for an electric shower heater?

I want to buy one does products but I don't know how many volt it - Elid Barahona 11/5/11


From an anonymous reader:

For Elid Barahona, Answer is: The Duromatic Electrical Instantaneous water heater is powered by 120 volts.
El calentador de agua eléctrico instantáneo Duromatic utiliza 120 voltios.
It's an excellent product. We installed it inside the wall May of 2008 & never a problem.
Es un producto excelente. Lo instalamos dentro de la pared en Mayo del 2008 y funciona bien. - Anon

We add that the voltage choices (120V or 240V) depend on

- what voltage you have at the building (in the U.S. usually 240V but certainly not everywhere)

- choice to spend a little more on wiring or on the device to save on hot water heating costs (240V is generally more efficient)

Photos of electric shower heaters used in the article above are used with permission and were provided courtesy of Arlene Puentes.


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