suggestions for an on demand electric water heater?  I want suggestions of a brand and model where, when the water heater is turned on high, the water is very hot.  We built our house 11 years ago and the water heaters worked so-so.  not really hot but the water was above warm.  they have all worn out over the years and need replacement.  I went out this morning and bought 2 8000W  on demand heaters and the water is not much higher than body temperature.  I want water heaters where the water comes out warm on the low setting but when it's turned up, I can actually take a steamy shower. 

 

suggestions?

Something is amiss, 8000 watt should give you just about boiling water. This morning with outside temp and about 14c, my 4000 watt heater at full power and half flow was more than hot enough, although at full flow its probably just above body temp. 

Have you checked voltage? 

Is there a power controller internal of the heater itself? 

Just now, Artisi said:

Something is amiss, 8000 watt should give you just about boiling water. This morning with outside temp and about 14c, my 4000 watt heater at full power and half flow was more than hot enough, although at full flow its probably just above body temp. 

Have you checked voltage? 

Is there a power controller internal of the heater itself? 

I did not think about that.  maybe the voltage is low.  that's a good idea to check that.  thanks

Temperature is flow dependent. If you have a shower head attached to the heater then 6.5 kW should be enough but not for producing "steam" from the shower but certainly just hot enough to stand under. I have a Panasonic  auto temp control unit which works OK. For a version that is feeding taps/faucets then a 8 kW Stiebel unit should be sufficient.

As other's have mentioned, entry original temperature and flow rate will affect output temperature.

To test, try turning down the flow rate until you get HOT HOT water coming out. See how efficient your unit is at what flow rate.

 

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Allowing the water to stay in contact with the heating element longer (lower flow rate) allows for higher output temperatures to be achieved. If you want to see higher output temperatures at higher flow rates then you'll need a higher BTU / Wattage unit, or gang devices together that allow pre-warming the water (such as a large Solar Loop, or additional water heater).

Edited December 22, 20178 yr by RichCor