"Phil Sherrod" wrote in message
...

On 30-Mar-2004, Richard J Kinch wrote:

Well done. I have performed similar experiments with similar results.
Idling losses are small. The tankless advocates are swindlers, but most
people don't have the critical faculties to understand the swindle.

Not as big as swindlers as the people selling timers for water heaters.
Most
people think that turning off a hot water heater for six hours is like
turning
off a light bulb for six hours. They don't realize that when the timer
turns
it back on most of the energy that was "saved" while it was off must now
be
spent bringing the water back up to temperature. The tiny savings is only
the
integral of the reduction in heat loss rate due to the small reduction in
temperature differential from the temperature drop which is probably just
a few
degrees.

Using high efficiency condensing water heaters will bring different results.
The lower the return temperature the more efficient they are. If you allow
a tank of water to cool and you re-heat it with a condensing water heater
the re-heat is very efficient in fuel use. Just top it up when the t'stat
drops a few degrees and the return water will not very cool at all.