Download Electric heating

King Saud University
College Of Engineering
Chemical Engineering Dept.
313 Che
Student Name : Mohammed saad
Alghamdi.
ID :
( 425 10 64 93 )
Dr : Malik Alahmed.
1
Introduction
A woven fibrous article that generates heat upon application of electrical power
has a woven fibrous body consisting of a set of non-conductive warp yarns and a
set of non-conductive filling or weft yarns. One of the set of non-conductive warp
yarns and the set of non-conductive filling or weft yarns, in one or more first
regions, consists of relatively more coarse yarns and in one or more second
regions consists of relatively more fine yarns with electrical conductor elements
extending generally along the second regions of the woven fibrous body to
connect the plurality of spaced apart electrical conductance heating elements in a
parallel electrical circuit to a source of electrical power. The other of the set of
non-conductive warp yarns and the set of non-conductive filling or weft yarns, in
the one or more first regions and in the one or more second regions, consists of
relatively more fine yarns, with a plurality of spaced apart electrical conductance
heating elements in the form of conductive elements joined in the woven fibrous
body with the other of the set of non-conductive warp yarns and the set of nonconductive filling or weft yarns to extend generally between opposite the second
regions of the woven fibrous body. In one embodiment, fleece may be formed on
one or both surfaces of the woven fibrous body by finishing fibers of the
relatively more coarse yarns in the one or more first regions of the set of nonconductive warp yarns or non-conductive filling or weft yarns, in a manner to
avoid damage to electrical conductivity performance of the conductive elements
joined with the set of yarns of the woven fibrous body. A method of forming a
woven fibrous article of the invention is also described .
Electric heating
Electric heating is any process in which electrical energy is converted to heat.
Common applications include heating of buildings, cooking, and industrial
processes.
An electric heater is an electrical appliance that converts electrical energy into
heat. The heating element inside every electric heater is simply an electrical
resistor, and works on the principle of Joule heating: an electric current flowing
through a resistor converts electrical energy into heat energy.
A heat pump uses an electric motor to drive a refrigeration cycle, drawing heat
from a source such as ground water or outside air and directing it into the space
to be warmed. Such systems can deliver two or three units of heating energy for
every unit of purchased energy.
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Design variations
Although they all use the same physical principle to generate heat, electric
heaters differ in the way they deliver that heat to the environment. Several types
are described in the sections below.
Radiative heaters or "space heaters"
Radiative heaters contain a heating element that reaches a high temperature.
The element is usually packaged inside a glass envelope resembling a light bulb
and with a reflector to direct the energy output away from the body of the
heater. The element emits infrared radiation that travels through air or space
until it hits an absorbing surface, where it is partially converted to heat and
partially reflected. This heat directly warms people and objects in the room,
rather than warming the air. This style of heater is particularly useful in areas
which unheated air flows through. They are also ideal for basements and garages
where spot heating is desired. More generally, they are an excellent choice for
task-specific heating.
They operate silently. Radiant heaters present the greatest potential danger to
ignite nearby furnishings due to the focused intensity of their output and lack of
overheat protection.
Convection heaters
In a convection heater, the heating element heats the air next to it by conduction.
Hot air is less dense than cool air, so it rises due to buoyancy, allowing more cool
air to flow in to take its place. This sets up a constant current of hot air that
leaves the appliance through vent holes and heats up the surrounding space.
They are ideally suited for heating a closed space. They operate silently and have
a lower risk of ignition hazard in the event that they make unintended contact
with furnishings compared to radiant electric heaters. This is a good choice for
long periods of time or if left unattended. They are very safe heaters and there is
a very low chance of getting burned.
In the United Kingdom, these appliances are sometimes called electric fires,
because they were originally used to replace open fires.
Fan heaters or "forced convection heaters"
A fan heater is a variety of convection heater that includes an electric fan to
speed up the airflow. This reduces the thermal resistance between the heating
element and the surroundings, allowing heat to be transferred more quickly.
They operate with considerable noise caused by the fan. They have a moderate
risk of ignition hazard in the event that they make unintended contact with
furnishings. This type of heater is a good choice for quick heating of enclosed
spaces; however, they should not be left unattended.
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Storage heating
A storage heating system takes advantage of cheaper electricity prices, sold
during low demand periods such as overnight. In the United Kingdom, this is
branded as Economy 7. The storage heater stores heat in clay bricks, then
releases it during the day when required.
Domestic electrical underfloor heating
These systems are called radiant heating systems, regardless of whether they
include a heat exchanger (also called a radiator) or are electrically powered.
When a home radiant heat system is turned on, current flows through a
conductive heating material. For high-voltage radiant heat systems, line voltage
(110 V or 230 V) current flows through the heating cable. For low-voltage
systems, the line voltage is converted to low voltage (8 to 30 V) in the control unit
(which contains a step-down transformer) and this low voltage is then applied to
the heating element.
The heated material then heats the flooring until it reaches the right temperature
set by the floor thermostat. The flooring then heats the adjacent air, which
circulates, heating other objects in the room (tables, chairs, people) by
convection. As it rises, the heated air will heat the room and all its contents up to
the ceiling. This form of heating gives the most consistent room temperature
from floor to ceiling compared to any other heating system.
Immersion heater
Water heating by electricity is usually done by an immersion heater. This
consists of a metal tube containing an insulated electric resistance heater.
Domestic immersion heaters (usually rated at 3 kilowatts in the UK) run on the
normal domestic electricity supply. Industrial immersion heaters (such as those
used in electric steam boilers) may be rated at 100 kilowatts, or more, and run on
a three-phase supply.
Electrode heater
With an electrode heater, there is no wire-wound resistance and the liquid itself
acts as the resistance. This has potential hazards so the regulations governing
electrode heaters are strict .(1)
Environmental and efficiency aspects
The efficiency of any system depends on the definition of the boundaries of the
system. For an electrical energy customer the efficiency of electric space heating
can be 100% because all purchased energy is converted to building heat.
However, if the power plant supplying electricity is included, the overall
efficiency drops. For example, a fossil-fuelled power plant may only deliver 4
units of electical energy for every 10 units of fuel energy released. Even with a
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100% efficient electric heater, the amount of fuel needed for a given amount of
heat is more than if the fuel was burned in a furnace or boiler at the building
being heated. If the same fuel could be used for space heating by a consumer, it
would be more efficient overall to burn the fuel at the end user's building. Not all
fuels are suitable for building heating; for example, emissions controls required
for coal combustion are too expensive for household-scale furnaces .
In Sweden the use of direct electric heating has been restricted since the 1980s
for this reason, and there are plans to phase it out entirely - see Oil phase-out in
Sweden - while Denmark has banned the installation of electric space heating in
new buildings for similar reasons. In the case of new buildings, low-energy
building techniques can be used which can virtually eliminate the need for
heating, such as those built to the Passive House standard.
In order to use electricity to provide heat efficiently, a heat pump driven by
electricity can boost the temperature of the heat in the ground, in the outside air,
or in waste streams such as exhaust air in order to use it as a heat source. This
can cut the electricity consumption down to as little as 20% and can reduce the
environmental impact.
Electrical space heating can still be economic where electicity supplies are lowcost. Where the primary source of electrical energy is hydroelectric, nuclear,
wind, or other carbon-free source, it may not be practical to exploit that resource
directly in heating applications but grid electricity can be conveniently used.
Electric space heating is useful in places where air-handling is difficult, such as
in laboratories.
Economic aspects
The operation of electric resistance heaters to heat an area for a long period of
time is generally considered to be costly. However intermittent or partial day use
can be more cost efficient than whole building heating since there savings due to
superior zonal control.
Example: A lunch room in an office setting has limited hours of operation.
During low use periods a "monitor" level of heat (50 °F/10 °C) is provided by the
central heating system. Peak use times between the hours of 11:00–14:00 are
heated to "comfort levels" (70 °F/21 °C). Significant savings can be realized in
overall energy consumption since infrared radiation losses through thermal
conductivity are not as large with a smaller temperature gradient both between
this space and unheated outside air as well as between the refrigerator and the
(now cooler) lunch room.
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Mathematical analysis
According to Joule's Law, the heat power produced by a resistor is:
P = IV
where
P is the power in watts
I is the current in amperes, and
V is the potential difference in volts,
and according to Ohm's Law I and V are related as follows:
V = IR
where
R is the resistance of the heating element, in
ohms.
We can combine these two formulae to obtain the heat output from the heating
element in terms of either current or voltage:
P=I2R
For heaters powered by AC mains, I and V are the root mean square (RMS)
values of current and voltage.
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Electrical Heating &Converting Waste Heat Into Electric Power
Control Systems for:
University of Utah physicist Orest Symko demonstrates how heat can be
converted into sound by using a blowtorch to heat a metallic screen inside a
plastic tube, which then produces a loud tone, similar to when air is blown into a
flute. Symko and his students are developing much smaller devices that not only
convert heat to sound, but then use the sound to generate electricity. The devices
may be used to cool electronics, harness solar energy in a new way, and conserve
energy by changing waste heat into electric power. Image Credit: University of
Utah
Hear This! Converting Waste Heat Into Electric Power
It sounds like magic but it is really science.
The University of Utah Physics Department has developed a way for devices to
take wasted heat derived from everyday processes and through converting the
heat to sound … one can then convert the sound to usable electricity.
The US Army is interested in funding this research activity because it is
interested in taking care of the wasted heat from radar operations in the field,
and also producing a portable source of electrical energy which one can use in
the battlefield to run electronics.
The process utilizes two steps with processes called "thermoacoustic prime
movers" and "piezoelectric" devices.
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Excerpts from Science Daily (the story has been adapted from a news release
issued by University of Utah) A Sound Way To Turn Heat Into Electricity
Science Daily, June 4, 2007
University of Utah physicists developed small devices that turn heat into sound
and then into electricity. The technology holds promise for changing waste heat
into electricity, harnessing solar energy and cooling computers and radars.
"We are converting waste heat to electricity in an efficient, simple way by using
sound," says Orest Symko, a University of Utah physics professor who leads the
effort. "It is a new source of renewable energy from waste heat."
Five of Symko's doctoral students recently devised methods to improve the
efficiency of acoustic heat-engine devices to turn heat into electricity. They will
present their findings on Friday, June 8 during the annual meeting of the
Acoustical Society of America at the Hilton Salt Lake City Center hotel.
Symko plans to test the devices within a year to produce electricity from waste
heat at a military radar facility and at the university's hot-water-generating
plant.
---Symko expects the devices could be used within two years as an alternative to
photovoltaic cells for converting sunlight into electricity. The heat engines also
could be used to cool laptop and other computers that generate more heat as
their electronics grow more complex. And Symko foresees using the devices to
generate electricity from heat that now is released from nuclear power plant
cooling towers.
How to Get Power from Heat and Sound
Symko's work on converting heat into electricity via sound stems from his
ongoing research to develop tiny thermoacoustic refrigerators for cooling
electronics.
In 2005, he began a five-year heat-sound-electricity conversion research project
named Thermal Acoustic Piezo Energy Conversion (TAPEC). Symko works with
collaborators at Washington State University and the University of Mississippi.
The project has received $2 million in funding during the past two years, and
Symko hopes it will grow as small heat-sound-electricity devices shrink further
so they can be incorporated in micromachines (known as
microelectromechanical systems, or MEMS) for use in cooling computers and
other electronic devices such as amplifiers.
Using sound to convert heat into electricity has two key steps. Symko and
colleagues developed various new heat engines (technically called
"thermoacoustic prime movers") to accomplish the first step: convert heat into
sound.
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Then they convert the sound into electricity using existing technology:
"piezoelectric" devices that are squeezed in response to pressure, including
sound waves, and change that pressure into electrical current. "Piezo" means
pressure or squeezing.
Most of the heat-to-electricity acoustic devices built in Symko's laboratory are
housed in cylinder-shaped "resonators" that fit in the palm of your hand. Each
cylinder, or resonator, contains a "stack" of material with a large surface area -such as metal or plastic plates, or fibers made of glass, cotton or steel wool -placed between a cold heat exchanger and a hot heat exchanger.
When heat is applied -- with matches, a blowtorch or a heating element -- the
heat builds to a threshold. Then the hot, moving air produces sound at a single
frequency, similar to air blown into a flute.
"You have heat, which is so disorderly and chaotic, and all of a sudden you have
sound coming out at one frequency," Symko says.
Then the sound waves squeeze the piezoelectric device, producing an electrical
voltage. Symko says it's similar to what happens if you hit a nerve in your elbow,
producing a painful electrical nerve impulse.
---Devices that convert heat to sound and then to electricity lack moving parts, so
such devices will require little maintenance and last a long time.
---Symko says the devices won't create noise pollution. First, as smaller devices are
developed, they will convert heat to ultrasonic frequencies people cannot hear.
Second, sound volume goes down as it is converted to electricity. Finally, "it's
easy to contain the noise by putting a sound absorber around the device," he
says.
Fan Forced Heaters
Corrosion Resistant Unit Heater
9
The Indeeco Triad ® unit heater is the perfect solution to the problem of
heating people or equipment in non-hazardous environments where
moisture and corrosion exist. Advantages of the TRIAD® include :

Built-in Controls : All necessary safety and temperature controls are
included in a single package. Components and motor are factorywired to a single terminal block for field wiring, eliminating the
chance for field error and reducing installation costs.
 Single Point Electrical Hook-up : Heater, fan motor and controls are
all connected to the same branch circuit.
 Corrosion Resistant : Stainless steel construction, epoxy-coated
aluminum fan blade and nonmetallic NEMA 4X terminal enclosure
resist ...
Industrial Unit Heater
In deeco’s industrial unit heater is designed for maximum heating
performance in non-hazardous and non-corrosive environments.
Features include:

Unique Design : Round design of the industrial unit heater provides
uniform airflow over the elements to prevent hot spots and ensure
even discharge temperatures. Circular stainless steel finned tubular
elements have a longer life due to lower operating temperatures.
 Built-in Controls : Heaters are completely assembled with all
electrical components built in at the factory to reduce installation
costs.
 Improved Performance : High CFM’s and air throw to 50 feet promote
air circulation within the space. More uniform temperature increases
comfort levels and helps to ...
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UCI Series Commercial Unit Heater
The UCI unit heater is designed for industrial and commercial
applications.

Large Capacity : Heavy-duty construction with ratings up to 60 kW at
2000 CFM.
 Control Options : Wide range of factory built-in or field installed
control options to meet job specifications.
 Single Point Electrical Hook-up : Heater, fan motor and controls are
all connected to the same branch circuit. Field connections and builtin controls are easily accessed in the side-mounted control
compartment.
 Discharge Direction : The UCI heater may be mounted horizontally
using one of two brackets (supplied) or vertically using four threaded
rods (not included).

UHI Series Commercial Unit Heater
The UHI unit heater provides quiet, reliable, horizontal airflow for
commercial and industrial applications.
Compact Design : Industry’s most compact 3-10 kW unit heater
design with performance that meets or exceeds other units on the
market.
 Factory Built-in Controls : Control options are built-in and wired at
the factory to meet job specifications, saving the cost of fieldinstalled kits.
 Single Point Electrical Hook-up : Heater, fan motor and controls are
all connected to the same branch circuit.

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
Balanced Three-phase Power : All three-phase heaters have balanced
loads, eliminating the need to phase balance unit heater electrical
loads within the building.
ULI Series Economical Unit Heater
The ULI unit heater is an economical choice for commercial heating
applications.

Compact Design : Ideal for primary or spot heating applications.
Units can be wall or ceiling-mounted for horizontal airflow.
 Versatility : Three different heater kW ratings can be field converted
to either 240 or 208 single-phase power.
 Built-in Adjustable Thermostat : Minimum temperature setting on
thermostat can be used to disable the heater.
UVI Series Vertical Unit Heater
The UVI unit heater is designed to heat buildings with high ceilings. It
may also be used to re-circulate warm air that builds up near ceilings.
UVI heaters can be used as primary, supplemental or dual heating
systems in commercial or industrial buildings.

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Vertical Airflow : Suitable for applications in high bay industrial
buildings where columns, machinery or warehouse stock would
obstruct horizontal air movement.

Air Distribution Patterns : Three optional air diffusers produce
different air distribution patterns to accommodate various
applications.
UPI Series Portable Unit Heater
The UPI portable unit heater provides clean, odorless backup heat in
indoor work areas. Rugged enough to provide temporary heat at
construction sites, this portable unit is well suited for commercial
heating applications.
Only available with almond finish.
Tubular & Finned Tubular Heating Elements
Tubular and Finned Tubular Elements
Indeeco designs and manufactures commercial and industrial
electric heating and control systems that set the industry
standard for excellence. The company’s heating solutions reflect
more than 70 years of innovation, product quality and efficient
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Our product offering ranges from the tubular heating elements
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Terminals, Insulators and Seals
Mounting Accessories
Bending
Standard single-pass tubular elements may be bent in an infinite variety
of configurations. Utilizing the most up-to-date computer numerical
control (CNC) bending equipment and techniques, Indeeco is able to
produce an element to fit virtually any application.
Bends that are less than 2" center-to-center are normally repressed on
unfinned elements to recompact the magnesium oxide insulation,
eliminating hairline cracks that may develop during bending.
Figures A through T show some of the configurations frequently
specified. For configurations not shown, submit a drawing or sketch of
your requirements. Any of these are available either finned or
unfinned.(2)
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What type of electrical heating is most cost effective for the
home?
Answer (1)
All electrical heating is 100% efficient. Every nickel you spend is converted into
usable heat unlike other sources, they just go up the chimmney. The type you
choose depends on you and where you are. You can go baseboard, there is a
calculation a qualified electrician will make for you so you get the right wattage
per room. This relies on the convection current principle to circulate the warm
air. You can get an electric arc furnace which uses forced air like the oil and gas
one. They are very quiet, of course efficient and have the "feeling" of warmth
because of the felt air. This of course is your option if you need central a/c as
well. You can go with radiant heat panels in your ceiling that fit between the
strapping on your rafters. So you have a clean sheet rock ceiling. Radiant panels
don't heat the air, they heat objects in that room. You can also go with radiant
heat inlaid in your flooring or subflooring heating the concrete, tiles, hardwood
or whatever.
So depending on where you live, you have to pick what's right for your locale.
It's clean, it's cheaper than fuels, require zero maintenance, and you don't waste
any of your money. Gotta like that.
Answer(2)
I think andy must work for the power company. Electricity is most definitely not
cheaper than gas, although with the way gas prices have been going, it might
become that way.
Electric resistance heat does indeed convert 100% of the incoming energy to
heat. But per amount of incoming energy, you pay a lot more for electricity than
you do for gas. You can get new gas furnaces that are 96% efficient. One can
argue that 4% inneficiency is infinitely greater than 0% inneficiency, but unless
the energy prices go totally topsy turvy, it still remains cheaper to heat with gas.
One thing that is overlooked in the above arguments is that with both electric
resistance heat and gas heat, the incoming energy must supply all of the heat. On
the other hand, with a heat pump, the heat comes from the outside air, and the
electricity is used only to move it inside. It works as an air conditioner in reverse.
In this way, you can actually get more heat energy out than the energy coming
into the house. The disadvantage is that heat pumps don't work if it gets too cold
outside. The older ones would only work down to 0 degrees C, but I think some
newer ones may work down to 0 degrees F.
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Central Heat Distribution
CHDL as seen from GM Place looking Southwest towards Downtown Vancouver
with the Georgia Viaduct in the foreground.
Central Heat Distribution Ltd. (CHDL) is a private Vancouver heat supplying
company located at 720 Beatty Street that provides heat to the Downtown Core
of Vancouver including the Vancouver Public Library Central Branch, B.C.
Place, GM Place, Queen Elizabeth Theatre, Pacific Centre and most major
hotel/office/condo towers such as Shaw Tower via a 10.5-km network of highpressure pipes. The world famous steam clock in Gastown is a notable addition
to the more than 180 buildings that are served by the natural gas powered boiler
located in the Stadium/Entertainment district of downtown.
The company was founded on November 1, 1968 by group of engineers with a
desire to lower heating bills for buildings (no boilers to buy and maintain) and to
reduce the amount of pollution being created to provide heat downtown.
The massive building CHDL occupies at the west end of the Georgia Viaduct was
once home to the printing plant for Pacific Press the publishers of The
Vancouver Sun and The Province newspapers.
Electric Boiler
Our range of electric boilers provides a very cost
effective alternative to electric storage heating,
oil, solid fuel or LPG systems.
It's the perfect solution for properties with no
access to mains gas supply and homes which
have gas boiler restrictions e.g. listed buildings
and bed-sit sleeping areas. Not only is the boiler
the ideal choice for wet central heating but it's also suited to Underfloor
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heating.
The Fusion Electric Boiler is one of the most complete electric boilers in
the market today. Unlike most Electric boilers, the Fusion was designed
to eliminate unnecessary external plumbing and pipe work.
The boiler has been engineered to include the Pump, Auto-air vent,
Expansion Vessel and Pressure Gauge within the compact casing. A
magnetic filter is also supplied with the boiler which must be installed
on the return pipework. As all sealed system components are contained
within the boiler this enables the boiler location to be flexible i.e. it can
be located either in a cupboard or wall mounted e.g. in the kitchen area.
To ensure maximum efficiency, the boiler boasts 6 stage heating using a
single copper heat exchanger.
With this unique facility both electricity consumption and running costs
are controlled through any heating cycle.
The easy to use control panel allows both the installer and home owner
to identify the operating temperature, flow rate and kW output of the
boiler at any given time.
The control panel also has an important part to play in fault diagnosis by
displaying fault codes which minimise unnecessary down time.
Our boiler outputs are 6kW, 9kW, 12kW and 14.4kW for properties which
require a higher output. It is also possible to install the boiler in series
with a secondary boiler to suit non domestic situations.
The operating temperatures of the boiler can be adjusted using the
control panel - the temperature outputs range from 40 degrees through
to a maximum of 85 degrees.
Incorporating the latest technology the Fusion Electric Boiler provides
complete peace of mind for reliability, performance and safety.
Electric Resistance Heating
Electric resistance heating converts nearly 100% of the
energy in the electricity to heat. However, most electricity is
produced from oil, gas, or coal generators that convert only
about 30% of the fuel's energy into electricity. Because of
electricity generation and transmission losses, electric heat
is often more expensive than heat produced in the home or
business using combustion appliances, such as natural gas,
propane, and oil furnaces.
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If electricity is the only choice, heat pumps are preferable in
most climates, as they easily cut electricity use by 50%
when compared with electric resistance heating. The
exception is in dry climates with either hot or mixed (hot and
cold) temperatures (these climates are found in the noncoastal part of California; the southern tip of Nevada; the
southwest corner of Utah; southern and western Arizona;
southern and eastern New Mexico; the southeast corner of
Colorado; and western Texas). For these dry climates, there
are so few heating days that the high cost of heating is not
economically significant.
Electric resistance heating may also make sense for a home
addition if it is not practical to extend the existing heating
system to supply heat to the new addition.(3)
Types of Electric Resistance Heaters
Electric resistance heat can be supplied by centralized
forced-air electric furnaces or by heaters in each room. Room
heaters can consist of electric baseboard heaters, electric
wall heaters, electric radiant heat, or electric space heaters.
To learn about electric radiant heat and electric space
heaters, see the radiant heating and small space heaters
sections. It is also possible to use electric thermal storage
systems to avoid heating during times of peak power
demand.
Electric Furnaces
Electric furnaces are more expensive to operate than other
electric resistance systems because of their duct heat losses
and the extra energy required to distribute the heated air
throughout your home. Heated air is delivered throughout
the home through supply ducts and returned to the furnace
through return ducts. If these ducts run through unheated
areas, they lose some of their heat through air leakage as
well as heat radiation and convection from the duct's
surface.
Blowers (large fans) in electric furnaces move air over a
group of three to seven electric resistance coils, called
elements, each of which are typically rated at five kilowatts.
The furnace's heating elements activate in stages to avoid
overloading the home's electrical system. A built-in
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thermostat called a limit controller prevents overheating.
This limit controller may shut the furnace off if the blower
fails or if a dirty filter is blocking the airflow.
As with any furnace, it's important to clean or replace the
furnace filters as recommended by the manufacturer, in
order to keep the system operating at its top efficiency.
Electric Baseboard Heaters
Electric baseboard heaters are zonal heaters controlled by
thermostats located within each room. Baseboard heaters
contain electric heating elements encased in metal pipes.
The pipes, surrounded by aluminum fins to aid heat transfer,
run the length of the baseboard heater's housing, or cabinet.
As air within the heater is warmed, it rises into the room,
and cooler air is drawn into the bottom of the heater. Some
heat is also radiated from the pipe, fins, and housing.
Baseboard heaters are usually installed underneath
windows. There, the heater's rising warm air counteracts
falling cool air from the cold window glass. Baseboard
heaters are seldom located on interior walls because
standard heating practice is to supply heat at the home's
perimeter, where the greatest heat loss occurs.
Baseboard heaters should sit at least three-quarters of an
inch (1.9 centimeters) above the floor or carpet. This is to
allow the cooler air on the floor to flow under and through
the radiator fins so it can be heated. The heater should also
fit tightly to the wall to prevent the warm air from
convecting behind it and streaking the wall with dust
particles.
The quality of baseboard heaters varies considerably.
Cheaper models can be noisy and often give poor
temperature control. Look for labels from Underwriter's
Laboratories (UL) and the National Electrical Manufacturer's
Association (NEMA). Compare warranties of the different
models you are considering.
Electric Wall Heaters
Electric wall heaters consist of an electric element with a
reflector behind it to reflect heat into the room and usually a
fan to move air through the heater. They are usually
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installed on interior walls because installing them in an
exterior wall makes that wall difficult to insulate.
Electric Thermal Storage
Some electric utilities structure their rates in a way similar
to telephone companies and charge more for electricity
during the day and less at night. They do this in an attempt
to reduce their "peak" demand.
If you are a customer of such a utility, you may be able to
benefit from a heating system that stores electric heat
during nighttime hours when rates are lower. This is called
an electric thermal storage heater, and while it does not
save energy, it can save you money because you can take
advantage of these lower rates.
The most common type of electric thermal storage heater is
a resistance heater with elements encased in heat-storing
ceramic. Central furnaces incorporating ceramic block are
also available, although they are not as common as room
heaters. Storing electrically heated hot water in an insulated
storage tank is another thermal storage option.
Some storage systems attempt to use the ground
underneath homes for thermal storage of heat from electric
resistance cables. However, this requires painstaking
installation of insulation underneath concrete slabs and all
around the heating elements to minimize major heat losses
to the earth. Ground storage also makes it difficult for
thermostats to control indoor temperatures.
Any type of energy storage systems suffers some energy
loss. If you intend to pursue an electric thermal storage
system, it would be best for the system to be located within
the conditioned space of your home, so that any heat lost
from the system actually heats your home, rather than
escaping to the outdoors. It would also be best to know how
quickly heat will escape from the system. A system that
leaks too much heat could cause control problems, such as
the accidental overheating of your home.
Control Systems
All types of electric resistance heating are controlled through
some type of thermostat: baseboard heaters often use a linevoltage thermostat (the thermostat directly controls the
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power supplied to the heating device), while other devices
use low-voltage thermostats (the thermostat uses a relay to
turn the device on and off). Line-voltage thermostats can be
built into the baseboard heater, but then they often don't
sense the room temperature accurately. It's best to instead
use a remote line-voltage or low-voltage thermostat
installed on an interior wall. Both line-voltage and lowvoltage thermostats are available as programmable
thermostats for automatically setting back the temperature
at night or while you're away.
Since baseboard heaters supply heat to each room
individually, they are ideally suited to zone heating, which
involves heating the occupied rooms in your home while
allowing unoccupied sections (such as empty guest rooms or
seldom-used rooms) to remain cooler. Zone heating can
produce energy savings of more than 20% compared to
heating both occupied and unoccupied areas of your
house.(4)
Conclusion
All electrical heating is 100% efficient. Every nickel you spend is converted into
usable heat unlike other sources; they just go up the chimney. The type you
choose depends on you and where you are. You can go baseboard, there is a
calculation a qualified electrician will make for you so you get the right wattage
per room. This relies on the convection current principle to circulate the warm
air. You can get an electric arc furnace which uses forced air like the oil and gas
one. They are very quiet, of course efficient and have the "feeling" of warmth
because of the felt air. This of course is your option if you need central a/c as
well. You can go with radiant heat panels in your ceiling that fit between the
strapping on your rafters. So you have a clean sheet rock ceiling. Radiant panels
don't heat the air, they heat objects in that room. You can also go with radiant
heat inlaid in your flooring or sub flooring heating the concrete, tiles, hardwood
or whatever.
Reference
1- http://www.tlc-direct.co.uk/Book/7.11.2.htm
2- The Green Electricity Illusion, AECB, published 2005.
3 - http://www.freepatentsonline.com/6888112.html .
4- Wilson.E , Vector Analysis , yale University Press, New Haven , 1901.
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