Re: Are electric WH timers worth it

FWIW, I have a small 67-litre/18 gallon, 1.5 kW/120-volt electric
water heater that pre-heats the supply feed to my indirect oil-fired
tank and my watt meter tells me the standby losses are a little less
than a 1.0 kWh per day. The exterior surface area of this tank is
roughly half that of a standard size model so, in theory, its losses
would be likewise about half. Then again, it's not as well insulated
and I keep the thermostat set at 70°C/160°F so, on that basis, I'd
expect the losses of a conventional tank to be more-or-less similar.

Why keep the tank set so high? Basically, to reduce the likelihood
that this water will be contaminated with legionella bacteria. To
whit:

"The optimal temperature for Legionella proliferation in water varies
between 32°C and 35°C [90° - 95°F], but it can easily proliferate at
temperatures of up to 45°C. Usually, there is no growth above 55°C,
and a temperature of over 60°C has a bactericidal effect. Thus, the
WHO recommends that water be heated and stored at 60°C. However,
studies in Quebec have shown, even when the thermostat is set at 60°C,
a high percentage (approximately 40%) of electric water heaters remain
contaminated because of the lower temperature, about 30°C to 40°C at
the bottom of the tank. The probability of contamination will increase
considerably if the temperature setting is lowered to 49°C."

Source:
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=2094925

Once established, legionella is, practically speaking, impossible to
eradicate.

Cheers,
Paul
.

Relevant Pages

  • Re: very small coldwater tank
    ... According to my super duper temperature converter, ... temperature to 60 F. From my perspective, when you say cold water, you ... the ordinary back ache heating pad under the tank. ...
    (rec.aquaria.misc)
  • Re: very small coldwater tank
    ... According to my super duper temperature converter, ... temperature to 60 F. From my perspective, when you say cold water, you ... the ordinary back ache heating pad under the tank. ... I heard one way was to use incandescent lamps, ...
    (rec.aquaria.misc)
  • Re: Basement hot water tank (electric) heat loss; yes again!
    ... the water supply and the circuit breaker for the electric hot water ... at the start when the tank was at full temperature, ... Which at 0.1 $ per k.watt hr. is/was a heat cost of 68.4 cents. ...
    (alt.home.repair)
  • Re: very small coldwater tank
    ... According to my super duper temperature converter, ... temperature to 60 F. From my perspective, when you say cold water, you ... the ordinary back ache heating pad under the tank. ...
    (rec.aquaria.misc)
  • Re: very small coldwater tank
    ... According to my super duper temperature converter, ... temperature to 60 F. From my perspective, when you say cold water, you ... the ordinary back ache heating pad under the tank. ...
    (rec.aquaria.misc)