PrecisionmachinisT wrote:
"Existential Angst" wrote in message
...
wrote in message
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A friend has a house that came with two identical water
heaters hooked up in parallel. He doesn't need all the capacity,
so we turned one of them off and turned off the water going
into it. This was several years ago. The water heater was
about 4 years old at the time, it's now 7 years old.

Given that a tank has already had some service, what would
you guys do to try to keep the spare tank available for as long
as possible?

Leave it full of water?

Drain it?

My thought was that draining it would be worse, because
allowing air in, it would rust.......



Fill it with water, add a rust inhibitor?

As an aside, shouldn't two water heaters be hooked up in series?
Been meaning to post that to the group. The rcm peeple should have
some insights into both Qs.

Having a second tank that's unpowered, uninsulated, and plumbed in
series so that cold water passes through it first will reduce
summertime AC and water heating costs by naturally warming the inlet
water up to room temp.

I am not sure, but I think that technically speaking that approach won't
save any money on energy costs. The reason is that for the water in the
first tank to be brought up to room temperature, it needs to draw its heat
energy from the room. So, it will cost that much more to heat the room
because some of the room heat is going toward heating the water in the first
tank. In other words, there is no free heat -- it either gets its heat from
being heated by at working hot water tank, or it gets its heat from the room
and that heat energy needs to be replaced by the heating system for the
room.