Charlie+ wrote in
:

On Tue, 14 Oct 2014 07:13:48 -0700, Jeff Liebermann
wrote as underneath :

snip
Incidentally, you might be amused at how water heaters are rated and
priced. A few years ago, the bottom of my 40 gallon electric water
heater filled with calcium carbonate causing the lower heating element
to blow out. It was rusted in place and not easily replaced. The
heater was old, so I decided a new heater was best. I went to the
local Home Depot store and noticed that heaters were rated and priced
by their warranty life as 6, 9, and 12 year heaters. Current prices
a
http://www.homedepot.com/b/Plumbing-...ntial-Electric
/N-5yc1vZc1u1Z2bcu0t?NCNI-5 $248, $338, and $548 respectively. I
asked what was the difference and received a few bad guesses. The
weight of these heaters was exactly the same, so there was no
difference in tank design or construction. The 6 year heater used
lower power elements, but that shouldn't effect the cost.

I eventually determined that the primary difference was the anode
protection rod in each heater. The 6 year heater used a very small
anode rod. The 9 year used a much larger anode. The 12 year had dual
anodes. The problem was the rods cost about $25/each which is
reflected in the $100 to $200 price difference between the three
models. The 6 year heater had the port for the 2nd anode sealed shut,
so I bought the 9 year model, and added a 2nd anode for a cost of
about $25. Net savings from the 12 year model:
$548 - $338 - $25 = $185
I also installed a permanent drain line, so that the calcium carbonate
will not accumulate again.
snip

What are these tanks made of that they need sacrificial anodes (of
magnesium etc. I assume)? As far as I know over here most/all these
type of tanks and cylinders are Cu sheet and have no anodes of this
type.. ! Informative post tho! C+

Over in the UK they tend to be copper or stainless and maintenance free
lifespans of 40+ years are not unusual. e.g. Albion brand stainless hot
water cylinders dont use any anodes and have a 25 year anti-corrosion
warrenty on the tank. The immersion heater element circuit should be RCD
protected, both for safety and so that any insulation failure will be
detected before significant electrolytic corrosion can occur.

Whoever first introduced vitreous enamel-lined mild steel hot water tanks
to the American market did you all a great disservice.

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
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