On Wed, 19 Mar 2008 04:32:02 -0700 (PDT), ransley wrote:

98% water heaters are common even 96% boilers

I think the reason for this is somewhat misleading.

If I understand this correctly, almost all the heat energy put into an
electric heater gets put into the water. Basically, the water cools the
heater coils down by taking the heat off the heater coil.

In the case of a gas water heater, the water cools down the flame by taking
heat off the flame (figuratively speaking) but a LOT of heat goes up the
flue.

They baffle the flue to slow down the rising air but they have to let the
hot air out. If they cooled the hot air to room temperature, it wouldn't
rise and get out of the house and that would be a bad thing from the
standpoint of carbon monoxide poisoning.

So, I think the fact that all none of the heat energy that went into the
electric coils goes up any flue - it's all absorbed by the water - is what
makes the electric water heater 98% efficiency.

But, as someone stated, I suspect the power generation is about 70%
efficiency, so, the true efficiency of electric water heating must be
vastly lower than 98% taking distribution into account.

But, how can we account for that true efficiency?

Donna