stan wrote:
On Apr 9, 9:36 pm, wrote:
Ernie Willson wrote:
It is true that the old incandescent bulbs do provide heat, however,
like resistance heat, they are very inefficient.
How is it inefficient if that heat is kept inside the
house?

It is not; ALL electricity coming into a house is turned into
something; all of which ends up as heat. Even if it starts off as
light or sound or a TV picture etc. it is all absorbed by the house,
it's furnishings and the people in it! (Well Ok a little light escapes
through the indows!)
We have a bathroom that is almost entirely heated by the six 40 watt
bulbs (240 watts) above the vanity mirror.
When additional heat is needed (cold weather) the 500 watt electric
baseboard with it's thermostat cuts in. Doesn't matter where the
electrically made heat comes from, it's all 100% efficient.
A few homes here are using (air) heat pumps; but gather that at lower
temps, well below freezing for long intervals they don't pump enough
heat from the cold air and the auxiliary electric heaters then cut in.
So there are long periods when the heat pump is not very effective.
(Or efficient!).

Stan,

Please cite a reference for your statement that heat pumps are less
efficient that incandescent bulbs or resistance heat??

For one kilowatt of energy consumed, incandescent bulbs will provide
very nearly one kilowatt of heating (the same goes for resistance
heaters). On the other hand a heat pump will provide something between
three and four kilowatts of heat for one kilowatt consumed. This means
that, compared to heat pumps, resistance heat is very inefficient. If
you don't understand this go to:

http://hyperphysics.phy-astr.gsu.edu.../heatpump.html

Where it says:

"Air conditioners and heat pumps are heat engines like the refrigerator.
They make good use of the high quality and flexibility of electric energy
in that they can use one unit of electric energy to transfer more than one
unit of energy from a cold area to a hot area. For example, an electric
resistance heater using one kilowatt-hour of electric energy can transfer
only 1 kWh of energy to heat your house at 100% efficiency.
But 1 kWh of energy used in an electric heat pump could "pump" 3 kWh
of energy from the cooler outside environment into your house for heating.
The ratio of the energy transferred to the electric energy used in the
process is called its coefficient of performance (CP). A typical CP for
a commercial heat pump is between 3 and 4 units transferred per unit
of electric energy supplied."

Simply stated this says that for one kilowatt of electricity consumed a
heat pump can provide between three and four kilowatts of heat. Put
another way, from a heating standpoint heat pumps are from 300% to 400%
efficient. I believe that this author is somewhat conservative and
modern CP's are more like 4 to 6.

EJ in NJ