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electric heater efficiency - Page 5

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Posted by Curbie on November 27, 2010, 2:51 am
That was my understanding that electricity was about 100% efficient,
and Natural Gas, Fuel Oil, and Wood were all about 80% efficient.


On Fri, 26 Nov 2010 20:24:38 -0500, "Ralph Mowery"

Posted by Jim Wilkins on November 27, 2010, 1:40 pm

The highest claim I've seen for wood is a little over 70% for a

Ole Wik's wood stove book reprints an old graph for the 1970's Jotul
118 that peaks at 76% for 1.4 Kg of wood per hour. It shows 65% - 70%
for the 3 - 4Kg I need in midwinter, which is optimized for least
smoke instead of best efficiency.


Posted by vaughn on November 27, 2010, 3:33 pm

The statement above, while technically true, is terribly misleading.  Saying
that electricity is "100% efficient" ignores the huge losses involved in
generating it and distributing it.  It especially ignores the fact BTUs directly
produced from electricity are typically damn expensive!   In truth, almost any
heating method is cheaper and more efficient than electrical resistance heating.

No need to take my word for it; check your local energy prices and do the math!
Convert everthing to cost/BTU to put everything on an apples-to-apples basis,
and then factor in the efficiency of your furnace to get your true price.    The
conversions you will need are below

Electricity: 3,413 btu per kilowatt-hour,
Gas: 1 Therm = 1,000,000 BTU, 1 cubic foot = 1020 BTU

Fuel oil/Diesel: 138,690

Propane/LPG: 95,475 BTU/Gallon  (100#" Gal.)

Wood: 18 to 24 million BTU per standard cord  (1 ton = 9 to 17 million BTU)

Coal: 16 to 26 million BTU/ton

As you can see, wood is the toughest to figure because the heat varies greatly
with the quality of the wood, and there are too many differing definitions of
what constitutes a cord.  Of course, if you get it for free...


Posted by Ralph Mowery on November 27, 2010, 3:52 pm

True,  It does not mater what the efficency is, it is the total cost to heat
your house that does.  While it is not 100% efficient, the heat pump is
usually much cheaper to run than pure electrical heat.  Especially if it is
above 30 deg. F.  Oil used to be a good way to go, but that was when it was
$ .15 per gallon instead of around the $ 3 to $ 4 it is now.

If you cut your own wood from your land next to your house, it is only a few
dollars for all year.  Mainly the cost of the gas for the chain saw.  Just a
lot of work.  A fellow at work told me he could put in a few hours of
overtime and pay for the cost of his heat.  Sure beat the amount of hard
work it would take him to cut the wood.

Posted by Balanced View on November 27, 2010, 4:07 pm
 Ralph Mowery wrote:

The problem of cutting wood is most tend to do it all at once instead of
a little at a time all year. We used to
cut mostly deadfalls when we had time and stack em up.

I haven't cut a tree in years though, there's an industrial park around
the corner that throws out enough pallets,
offcuts and crates to heat an arena. I used the offcuts from a cabinet
shop to heat my place for five years, all kiln
dried oak, maple,hickory and cherry, usually 1 x 4 x 4-8" long. There
was never any creosote build up in the pipes
from that stuff ;~)

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