According to Phil Sherrod :
On 30-Mar-2004, (m Ransley) wrote:
Well Phil your calculations on tankless vs tank are not quite accurate.
You also forgot that Tanks unless flushed regularly loose efficiency
every year. I just had a tank replaced in a bldg it had over One Foot
of scale- crap in it after 17 yrs. Now that reduced efficiency apx 20
-25 %
17 years is a pretty long life for a water heater.
Scale reduces the volume of the tank, it does not reduce efficiency nor does it
increase power usage. The scale will be at the same temperature as the water,
so it will radiate heat at the same rate.
Not quite. Scale does not "circulate".
Thermal regulation will suffer, recovery time will suffer (possibly extremely),
more heat will be lost out of the tank due to overswings/higher delta-Ts,
insulative effects etc.
Scale will also shorten the lifetime of the elements - it sure did mine :-(.
For figures on savings you are wrong. I know people that say the same
as me 25- 50 % in costs of operation. saving 15 - 40 a month.
There are allot of people with tankless , they are how you should base
your opinions. Real world everyday use. Not guesstimates.
The whole point of my analysis was to avoid "guestimates". What guess are you
saying I made? Rather than guessing, I took accurate measurements that show the
total energy cost due to heat loss is about $4/month. If you are saving more
than that you are either (1) using less hot water or (2) using a cheaper source
of energy such as gas.
It's easy to contrive examples of where timers/demand heaters/etc will either
save you lots, save you insigificant amounts, or actually cost you more money.
There are LOTS of factors involved - duty cycles, temperature settings, usage
patterns, age, tank insulation quality, pipe insulation/size, tank size, energy
costs etc.
Whether any specific measure will be worth the effort depends a lot more on
your unique circumstances than the technology per-se.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.