electric heater efficiency

[james]

Saw an ad for energy efficient heater, which prompted this question:

Aren't all electrical heater equally efficient in converting electricity to
heat?

If not, where do the lost energy go? Don't they all get converted to heat
sooner or later?

The only way I can think of to consume electricity and not generate heat is
to radiate off the energy as electromagnetic wave (radio wave, x-ray, etc)
which can radiate away into infinity and not generate heat.

 

[vaughn]

Saw an ad for energy efficient heater, which prompted this question:

Aren't all electrical heater equally efficient in converting electricity to
heat?

Yes, all resistance electric heaters are equally inefficient at converting
Watt-hours to BTUs. Some heaters may be better than others at putting those
BTUs where the people are in the room.

If not, where do the lost energy go? Don't they all get converted to heat
sooner or later?

There are some heaters that are being marketed with a generous dose of snake
oil. I actually had some respect for Bob Vila before he hitched his name to
one.

The only electric heaters out there that can save any significant amount of
electricity are heat pumps.

Vaughn

 

[Josepi]

We went through this wave of "Microfurnace" comes to mind years ago. The
ceramic heater and high-efficiency crap. It's all CRAP.

The Canadian Consumer and Corporate Affairs got involved last time and
deemed them the same efficiency.

Now if you get a graduated heater that can put out only the heat desired and
not cycle on and off for heat waves then you may save 1 or 2% or just be
more comfortable.

Careful about the ceramic puck heaters. We had one short out internally and
shoot flames out of the front. On a carpet it could be disasterous.

Save your money to buy a magnetic water softener...ROFLMFAO. We need bigger
prisons.


Saw an ad for energy efficient heater, which prompted this question:

Aren't all electrical heater equally efficient in converting electricity to
heat?

If not, where do the lost energy go? Don't they all get converted to heat
sooner or later?

The only way I can think of to consume electricity and not generate heat is
to radiate off the energy as electromagnetic wave (radio wave, x-ray, etc)
which can radiate away into infinity and not generate heat.

 

[Jim Rojas]

We went through this wave of "Microfurnace" comes to mind years ago. The
ceramic heater and high-efficiency crap. It's all CRAP.

The Canadian Consumer and Corporate Affairs got involved last time and
deemed them the same efficiency.

Now if you get a graduated heater that can put out only the heat desired and
not cycle on and off for heat waves then you may save 1 or 2% or just be
more comfortable.

Careful about the ceramic puck heaters. We had one short out internally and
shoot flames out of the front. On a carpet it could be disasterous.

Save your money to buy a magnetic water softener...ROFLMFAO. We need bigger
prisons.


Saw an ad for energy efficient heater, which prompted this question:

Aren't all electrical heater equally efficient in converting electricity to
heat?

If not, where do the lost energy go? Don't they all get converted to heat
sooner or later?

The only way I can think of to consume electricity and not generate heat is
to radiate off the energy as electromagnetic wave (radio wave, x-ray, etc)
which can radiate away into infinity and not generate heat.

I live in Florida. To save money, I use the oil filled plug in heaters
that you can buy at Walmart. I set it on #3 setting, and use only the
lower element. It keeps the room nice and cozy. My central air heat pump
just uses too much power. There is no need to heat up rooms no one
sleeps in.

Jim Rojas

 

[Josepi]

That makes sense for your climate and in general but the oil filled is only
a comfort feature and doesn't save money, especially vs. a heat pump with a
3:1 COP or better.

Need some zone controls there, and/or more thermal mass to carry heat
overnight and cool over the day. One guy here put up large pipes full of
water to stretch the heat periods longer (desert type climates profit well
from this stuff)



I live in Florida. To save money, I use the oil filled plug in heaters
that you can buy at Walmart. I set it on #3 setting, and use only the
lower element. It keeps the room nice and cozy. My central air heat pump
just uses too much power. There is no need to heat up rooms no one
sleeps in.

Jim Rojas

 

[Jim Rojas]

That makes sense for your climate and in general but the oil filled is only
a comfort feature and doesn't save money, especially vs. a heat pump with a
3:1 COP or better.

Need some zone controls there, and/or more thermal mass to carry heat
overnight and cool over the day. One guy here put up large pipes full of
water to stretch the heat periods longer (desert type climates profit well
from this stuff)



I live in Florida. To save money, I use the oil filled plug in heaters
that you can buy at Walmart. I set it on #3 setting, and use only the
lower element. It keeps the room nice and cozy. My central air heat pump
just uses too much power. There is no need to heat up rooms no one
sleeps in.

Jim Rojas

That would be ideal for new homes. My house was built in 1964. It
originally didn't even have central air.

When we remodeled the house, we installed 3 inch foil backed sytrofoam
in the attic, followed with R34 a year later. Before we did the stucco
finish on the concrete block, they drilled 1/2 inch holes every foot all
around the house. Then they injected expanding foam into the nterior
walls. It cost us $2500 to do this, and we got a 1500 rebate from our
utility company. All our windows are double insulated.

In the summer months the AC runs for very short periods of time to keep
the house at 76-78 degrees.

Jim Rojas

 

[Gordon]

Saw an ad for energy efficient heater, which prompted this question:

Aren't all electrical heater equally efficient in converting
electricity to heat?
Yes.

If not, where do the lost energy go? Don't they all get converted to
heat sooner or later?

The fan uses some electricity that isn't converted to heat.
But it is a very small amount.

The only way I can think of to consume electricity and not generate
heat is to radiate off the energy as electromagnetic wave (radio wave,
x-ray, etc) which can radiate away into infinity and not generate
heat.

But, when the radio wave is absorbed by an object, it heats it.
CF: A microwave oven.

 

[vaughn]

just uses too much power. There is no need to heat up rooms no one sleeps in.

Also in Florida, we installed a mini-split reverse cycle AC in our bedroom.
Winter or summer, that is the only nighttime AC or heat running in our house. It
is more efficient than our (older) central unit, and so quiet it's hard to tell
when it's running. If we weren't empty nesting, I would do the same with the
other bedrooms. In the daytime, the bedroom doors are closed and the central AC
vents to them are closed off. There is no need to heat or cool empty rooms.

Vaughn

 

[vaughn]

After all, a muggy 73 degrees can be far less comfortable
than a drier 83 degrees.

We figured that out the hard way when we tried to cool our bedroom with one of
those one-hose portable AC units. The problem was, for every cubic foot of hot
air that box blew out of the house, another cubic foot of saturated Florida
mugginess infiltrated from outside. The result? Cool and uncomfortable. Never
use a one-hose portable AC in a high-humidity area! We sent that one to my
daughter in California. There, it works great.

Vaughn

 

[Curbie]

The fan uses some electricity that isn't converted to heat.
But it is a very small amount.

Why doesn't the electricity the fan uses convert to heat?

Curbie

 

[Curbie]

That was my understanding that electricity was about 100% efficient,
and Natural Gas, Fuel Oil, and Wood were all about 80% efficient.

Curbie

 

[Bob F]

I live in Florida. To save money, I use the oil filled plug in heaters
that you can buy at Walmart. I set it on #3 setting, and use only the
lower element. It keeps the room nice and cozy. My central air heat
pump just uses too much power. There is no need to heat up rooms no
one sleeps in.

There is no need to heat the room I sleep in here in Seattle. I've got 3
comforters which keep me toasty all night with the house as low as 45F. The bed
room is the last one I'd heat, except for certain special occasions. A standard
space heater takes care of those just fine, and warms up the bed in 2 minutes if
needed when I climb in.

 

[Jim Rojas]

There is no need to heat the room I sleep in here in Seattle. I've got 3
comforters which keep me toasty all night with the house as low as 45F. The bed
room is the last one I'd heat, except for certain special occasions. A standard
space heater takes care of those just fine, and warms up the bed in 2 minutes if
needed when I climb in.

45 degrees? Ouch. My tropical fish would have a cow. I do have heaters
in my fish tanks, but damn.

Here in Florida when it hits 60 degrees all my neighbors break out the
Alaska winter gear. They wear ski jackets, parkas, gloves, knitted hats,
and scarfs.

I was born in New York City. I wear shorts & short sleeve polo shirts no
matter how cold it gets here. Last year it hit 25 degrees a few times.

Jim Rojas

 

[Jim Rojas]

There is no need to heat the room I sleep in here in Seattle. I've got 3
comforters which keep me toasty all night with the house as low as 45F. The bed
room is the last one I'd heat, except for certain special occasions. A standard
space heater takes care of those just fine, and warms up the bed in 2 minutes if
needed when I climb in.

45 degrees? Ouch. My tropical fish would have a cow. I do have heaters
in my fish tanks, but damn.

Here in Florida when it hits 60 degrees all my neighbors break out the
Alaska winter gear. They wear ski jackets, parkas, gloves, knitted hats,
and scarfs.

I was born in New York City. I wear shorts & short sleeve polo shirts no
matter how cold it gets here. Last year it hit 25 degrees a few times.

Jim Rojas

 

[vaughn]

That was my understanding that electricity was about 100% efficient,
and Natural Gas, Fuel Oil, and Wood were all about 80% efficient.
Curbie

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#=22 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...



Vaughn

 

[danny burstein]

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

Maybe to those folk who write Congressional impact
statements... but to the rest of us a therm is 100,000 BTU

"Therm - One therm equals 100,000 Btu. " [a]

[a] http://www.eia.doe.gov/ask/ng_faqs.asp#ng_conversions

(and for the purposes of discussion, a therm can be
taken as being equal to a "ccf", aka a hundred cubic
feet of natural gas).

(what's a typo among friends?)

 

[Balanced View]

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.

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 ;~)

 

[Curbie]

Jim,

So you think 60-65% would be a reasonable efficiency number for
estimations in wood stove planning?

Curbie

 

[Curbie]

Vaughn,

Even though the post I was responding to was about the efficiency of
converting electricity to heat, I think it's a valuable reminder that
there are also costs involved with production and transportation of
energy, but it in an "apples to apples" comparison, we would also have
to consider those costs for natural gas, propane, fuel oil and wood,
not just electricity.

You posted some good information which I agree with the exception the
issue Danny Burstein already pointed out.

Thank,

Curbie

 

[vaughn]

"Therm - One therm equals 100,000 Btu. " [a]
(what's a typo among friends?)\

Exactly. My conversion factors are worth what you paid for them, perhaps less.
Check, check, check.

Vaughn