In misc.industry.utilities.electric Phil Sherrod wrote:

| Timers that turn off the water heater for a few hours are virtually useless
| because nearly all of that energy is put back in to reheat the water when the
| timer turns back on. Now, if you're going to be away for a week or month, you
| might save a little money because the tank will have time to cool down and stop
| losing energy through the insulation. But the temperature drop over a 6 hour
| period is only a few degrees, so the reduction in heat transfer through the
| tank due to that small drop is practically insignificant. When the timer turns
| on, the heating element runs continuously for many minutes to bring the entire
| mass of water back up to the set temperature, and that energy will nearly equal
| the energy "saved" during the time that the heater was turned off.

If your utility charges less at night, then you can see financial benefits
from such a timer. I believe more and more utilities will be going thois
route as they deploy more smart digital meters.


| If you are going to try to increase the efficiency of a hot water heater, it is
| better to use an insulating jacket than a timer. But regardless of what you
| do, you won't save more than $4/month unless you either (1) reduce your hot
| water usage or (2) change to a cheaper source of energy (gas, heat pump, solar,
| etc.).

If you are actually using water (e.g. it's flowing and regular gets heated)
then pre-heating the water by some other means (like discard heat from the
air conditioner in summer, or solar heating, etc) before it enters the tank
could save some money. Rather than merely changing the heat source, this is
more of a diversity. For example it works in winter when the A/C is not in
use, and in cloudy weather when the solar won't do so well, by drawing more
electricity only at those times, but you still get hot water at the desired
temperature.

A larger tank should help, given a smaller surface to lose heat from. I am
wondering if it is worthwhile to heavily insulate the closet the tank is in.
Or might that just end up creating too much heat rise in the closet? The
best would be very well insulated tanks.

I once was favoring tankless instant heat. But now I'm looking at that as
only a backup, if at all.

--
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| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
| (first name) at ipal.net | http://phil.ipal.org/ http://ka9wgn.ham.org/ |
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