wrote:
The Wiki strikes again... another one for review



This article compares the various types of electric space heating.


==All types==
A few things apply to all of them.

All electric heaters are 100% efficient, none of the heat goes
outdoors.

At point of use...

All are exempt from the annual inspections required of gas appliances
in rented properties.

Other advantages include: the don't generally introduce extra moisture
into the room.

==Plug in heaters===
These are all much more expensive to run than all other mainstream
heating options, at around 3-4x the energy cost of mains gas.

A comparison to oil and LPG might be useful.

Thermostatic models prevent room overheating, which wastes money &
energy.

That does not quite read right - how about "Thermostatic models prevent
room overheating, which saves energy and money"

Plug-ins are best suited to just occasional use, where their high run
cost and zero installation cost makes sense.


===Fan heater===
High energy cost, usually fairly high power, fast heating, small,
noisy, fire risk if covered.

Many fan heaters have a lower power setting - typically 800 - 1000W.
This is small enough to run from a standard mechanical thermostat. This
makes them (especially when wall mounted) ideal for frost protection in
things like tool stores or workshops.

===Convector===
High energy cost, medium power, medium size, no noise, less fire risk
if covered.

===Electric Radiator===
High energy cost, lowish power, slow, large. Some only reach a
moderate temperature, and are touch safe, no fire risk, and can be
used to dry clothes. Some get hot enough to burn things though.
Relatively good around kids and the infirm, though they're heavyish
and can be knocked over. More tolerant of minor water spills than most
other portable heater types. Some have a radiator temperature control,
some don't.

Do we need the "high energy cost" prefix to every paragraph? - The point
has been made in the introduction.

===Bar fire===
These radiate heat from a red hot bar. Older models tend to be
dangerous, with an exposed red hot live bar, inadequate guarding, and
they tend to catch fire if something falls on them. They also seem to
attract naughty kids that like to experiment. New models have improved
guarding, but no other benefit.

Replacement heating bars are available if one fails, but a better
heater is usually preferable.


===Halogen heater===
A more modern version of a bar fire, these use a red halogen lamp in
place of the bare bar. The lamp is insulated rather than bare & live.
The heat density isn't as high (400w per bar is typical), reducing the
fire risk.

Might be worth pointing out that these are effective at heating people
rather than rooms - hence less power can be used to keep you feeling
warm when in a cold environment. Handy for workshops, sheds etc.

Can also be used as patio heaters - since they will radiate heat at
people and are not affected by draughts etc.

The halogen lamps last far longer than visible light lamps, but they
don't last forever. Replacement infra red lamps are available.

===Tubular heater===
Tubular heaters are low power (typically from 60w to 300w) and low
power density heaters designed to remain safe if a coat etc falls on
them. These are used where items might fall on them, for pipe freeze
protection, to keep frost off greenhouses, etc. The safest of all plug-
in heater types. More tolerant of minor water spills than most other
portable heater types.

Typical application includes use in airing cupboards, and for reducing
condensation and mould in problem areas.

==Heat pump==
There's only one type of electric heating that can beat 100%
efficiency, and that's a heat pump. These can give equivalent to 300%
efficiency by using the leccy to pump heat in from outdoors. Since all
heat pumps take heat from outdoors, they must be installed one way or
another.

Not sure that reads well as a section intro...

Something like:

Heat pumps transfer heat from one place to another. Typically from
outside of a building to the inside. The energy they consume is also
output as heat. Hence they are the most efficient electrical heaters
available, since thy will actually contribute more energy to a room than
they consume.

There are several types including:

===Air source heat pump===
Air source heat pumps are the cheapest heat pump. These use a coil and
fan to extract heat from the outdoor air.

"Air source heat pumps are the most common form of heat pump. They are
often built into air conditioning units. By changing the direction in
which they are pumping they can be used to heat in the winter and cool
in the summer. "

The downside of air source heat pumps is that efficiency and hence

a limitation of -

energy delivery falls as outdoor temp falls. When the outdoor coil
freezes, which happens somewhere in the region of 5C and below,
efficiency drops much further, making them ineffective heaters at such
times.

Sometimes the units are reversable, also able to operate as air
conditioning in summer.

don't really need that last bit

===Ground source heat pump===
The downsides of ground source heat pumps are that a huge and costly
layer of ground tubing needs to be laid. This takes a large area of
ground.

What about the upsides? Better ratios, can be used for cooling as well,
can be used for heating thermal stores and not just air etc.

===Geothermal source heat pump===

Many of the advantages of ground source, but without the need for
significant areas of land to be used for piping. These use a borehole
drilled into the ground - preferably into the water table.

The downside is installation cost:

don't need the rest

a bore hole must be drilled, and a
long heat source tube lowered into the water in it. These use less
than a square foot of land.

I would put these after plug ins and before heat pumps since they sit
between them in running costs.

==Storage heaters==
These heat up a pile of firebricks overnight on cheap rate electricity
(using economy 7 & similar schemes). During the day the stored heat is
let out by controlled flaps.

Could we reword "controlled flaps" somehow?

The main downside of storage heating is poor controllability, poor
weather prediction, and sometimes they run out of heat before
recharging time. Some newer models access weather forecasts in a bid
to improve performance, how successful this is I don't know.

they also frequently don't fit typical patterns of usage - giving out
lots of heat when no one is home and starting to cool just when you need
them most.

Storage heaters are bulky compared to radiators.

One aught to include a heat bank here. This avoids the controllability
and delivery time limitations of the conventional storage heater since
it behaves as a wet central heating system but with the heat being
stored it the store water until it is required. Also makes it easier to
augment the electrical heating with other sources like solar, solid,
fuel etc.

Storage heating is the second cheapest method of electric heating to
run (only heat pumps cost less), and its suitable for all weathers,
making it one of the most common choices. The run cost is still
significantly higher than mains gas.

Note that daytime rates are often slightly higher on E7 type schemes,
so the savings tend not to be quite as good as they appear.


==Under floor heating==
UFH is available in piped water and electric forms. The electric
version is much more expensive to run.

The main advantages of UFH are that no heating equipment is visible,
and it provides a comfortable warm floor. The warmth is especially
appreciated with a tiled floor, and in bathrooms.

When installed on a ground floor it requires [[insulation]]
underfloor. Usually this means taking up the existing floor, but there
are thin insulation boards that allow heating to be laid on top of an
existing floor.

UFH can't usefully be powered by cheap rate electricity. UFH has a

see heat bank above...

significant time lag, so must be timed to turn on before the heat is
needed. For these reasons, electric ufh is inherently not a cheap
option. Heating cable failure can occsaionally happen, and this
creates additional expense if the floor is tiled or otherwise
permanently finished.

Pipe based ufh driven by the central heating boiler is preferred
wherever this is usable, as its much cheaper to run, and more reliable
long term.


==Halogen radiant==
Wall mounted halogen radiant heaters produce radiant heat plus red
light. The principle is exactly the same as halogen plug-in heaters,
and their shortcomings the same. They bneed to be mounted high up to
reach all areas of the room, and the amount of red light given out at
near eye level can cause some visual discomfort. For this reason they
tend to see more use in commercial spaces.

already done this one toward the top of the article...

==Obsolete==
Obsolete types of electric heating are still occasionally encountered.

===Ceiling radiant heat===
Ceiling mounted radiant heaters are occasionally seen in 1960s
properties. Since heat rises, these give poor performance, with rooms
cold at the floor and hot near the ceiling. This increases energy use
and losses.

If they are predominantly radiant, then the heat will not be rising
necessarily ;-)

===Bowl heater===
These were popular from the 1920s to 50s, but are rarely seen today.
These are economical radiant heaters for use in cold houses, as more
of the radiant heat is directed to the person sitting nearby, compared
to a bar fire. Usually rated at a few hundred watts, these are
intended to take the chill off an otherwise unheated space.

They have all the defects of bar fires, plus instability, which
increases the fire risk further. Also their age makes them generally
fail to meet even basic electrical safety standards. They have little
chance of passing a PAT test and should not be used.


==See Also==
* [[Insulation]]
* [[Heating]]
* [[Special:Allpages|Wiki Contents]]
* [[Special:Categories|Wiki Subject Categories]]



[[Category:Heating]]
[[Category:Electrical]]


Not bad. The tone could do wit a little lightening in places - it tends
to dwell on costs and downsides. It would be handy if it gave hard
information on getting the best from electric heating (i.e. some of the
less common stuff like supplementary thermostats, heat pumps, thermal
stores etc) - especially when in some cases that is what a user will be
stuck with.


--
Cheers,

John.

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