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

| On 30-Mar-2004, wrote:
|
| 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.
|
| Most people have their timer set to turn their heaters OFF at night and back on
| in the morning when they are ready to shower. Most of the energy consumption
| will come during the morning reheat and during the period after their show when
| the water heater is heating the cold water that was drawn in. So I don't see
| how lower night power rates will apply.

Heat all of a day's hot water needs overnight. That does require a larger tank.


| A larger tank should help, given a smaller surface to lose heat from.
|
| The closer the tank shape is to spherical, the better it is. You want to
| minimize surface area for a given volume of water. However, you don't really
| have a lot of choice here; I've never seen a spherical water heater.

I have seen a hot water heater with a spherical tank. But it was not
very large. One has to consider space utilization issues, construction
cost issues, etc. Cylindrical does seem to wokr out best in most cases.


| I once was favoring tankless instant heat. But now I'm looking at that as
| only a backup, if at all.
|
| I don't think a tankless heater makes sense from an energy point of view. The
| only advantage is that you have an unlimited quantity of hot water.

A tankless water heater uses less energy overall. But it uses that
energy when energy costs (demand) is higher, so it is, in the end, a
disadvantage. It's higher current drawn, and lack of wattage step-up,
means it causes more significant voltage sags when it kicks in.
Electric utilities don't like them for that reason (because neighbors
complain that lights blink). If, OTOH, you have a large solar power
system, it might make sense to use them.

Energy storage is a key, here, and a hot water tank is one form of storage.

--
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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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