Heating - Heat Emitters - Page 1 2 3 4 
Question:
List 3 advantages and 3
disadvantages of the following types of heating systems.
1. Radiant panels using MTHW.
2. Underfloor heating using plastic tubes
with LTHW.
3. Electric Infrared panels.
4. Fan convectors.
5. Floor standing unit heaters.
Answer:
1.
Radiant panels using MTHW
Fabricated radiant heated
ceiling panels using medium temperature hot water can provide a surface
temperature between 100 – 180 oC, which produces a powerful
radiation output.
The product is one of the
most cost effective and energy efficient radiant heaters available with a
pleasing appearance. Its method of construction allows ease of fixing in a wide
range of applications. In addition, the heating grid and face panels are
installed separately as first and second fix items respectively. This means
that the coloured and contoured face panel work is not subject to site damage
during early stages of construction.
One of the important aspects
of radiant heating is that it is totally quiet.
Radiant panels can be very
useful in a medical situation where no forceful air movement is permitted i.e.
operating theatre. Radiant panels would be a very useful and workable method of
heat transfer in this type of situation.
Radiant panels do not
inhibit or take up any wall space, which can be a great advantage in the
following situations;
Sports halls, hospital
wards, corridors, classrooms, laboratories, factories, open plan office areas
and workshops
MTHW Radiant panels in a factory situation
MTHW Radiant panels in a hospital situation
Disadvantages
of MTHW radiant heated ceiling panels
Radiant panels require
controls in order that the panels operate effectively and efficiently. These
controls (Diverting Valves) require a lot of maintenance on the actuators. This
can be a big disadvantage for examples in a factory, as your controls for each
panel may be 10 or 15 metres up at roof level where the panels are and to carry
out a regular maintenance check is a major job.
Radiant panels using MTHW
can run at very high surface temperatures (100 – 150oC ).
This can be very dangerous
in a school application because it pupils can get access and touch the panel it
will cause serious burning to the skin or if the waterways within the panel
leak in a class room the can again cause serious burning.
If a radiant heated ceiling
panel is used in a factory situation and installed at lower levels than the
roof this can inhibit the maximum working height for the machinery within the
factory.
In an engineering
application where by cranes are used this will cause all sorts of problems.
2.) Underfloor
Heating using plastic tubes with LTHW.
Advantages
using underfloor heating
Underfloor heating is a
very efficient method of heat transfer, which in turn keeps fuel costs at a
minimum. Underfloor Heating can save 20-40% on your monthly heating bills.
Radiant floor heating is an
efficient delivery system when compared to small vents or radiators that try to
blast enough heat into a room to warm it up. Heat stays near the floor where
it's needed, not wasted at the ceiling as shown below.
Cross section showing underfloor heating
Under floor heating has a
major advantage over perimeter heating, as no wall space is required in order
to heat up rooms. As the system is encased in the floor, furnishings can be
placed wherever you desire without concern for impairing heat distribution or
hiding unsightly heating appliances.
In addition,
Underfloor-heating systems can be installed under any type of flooring,
including wood, tile, concrete and carpet.
Underfloor heating allows
room by room temperature control, allowing more heat where you want it most.
The drawing below shows a
typical example of Underfloor heating installed in a house application. As you
can see all wall spaces are available.
Underfloor heating is
relatively easy to install and places little strain on your body, as there is
no heavy lifting involved. As well as being easy to install Underfloor heating
can be installed in a very short space of time which can be very useful in a
very tight construction program.
Disadvantages
of using underfloor heating
Underfloor heating has a
very slow heat up period somewhere in the region of 5 to 6 hours on cold
morning. This means that careful monitoring must take place in order to ensure
that the controls are set up correctly to overcome the disadvantage to
Underfloor heating.
Under floor heating can
have a lack of control, for example during a spring morning the controls will
call for heat to the serve the manifolds, as the morning may be cold.
But say for example around
11 o’clock and the sun comes out the building will start to obtain solar gains,
which in turn will rise the temperature in certain rooms.
At this point the controls
turn off, but due to the nature of Underfloor heating, the structural slab
still remains warm at 24oC and in turn will still heat the room for
several hours
This situation can cause a
major overheating problem.
The room temperature at 2
o’clock may be around 31oC, which is too high!
Once Underfloor heating is
installed in the floor screed it can de very hard to repair if a burst occurs,
by someone drilling a hole in the ground and puncturing one of the loops.
This is a disadvantage, as
part of the floor screed has to be dug up the pipe fixes and the floor screed
fixed again.
3.) Electric
Infrared Panels
Advantages
using Electric infrared panels
Electric infrared panels
are often used in public buildings such as schools and day-care centres. They
are very similar to radiant heated ceiling panels and have similar advantages.
Electric infrared panels
are very useful in a medical situation where by no forceful air movement is permitted
i.e. operating theatre. Electric infrared panels would be a very useful and
workable method of heat transfer in this type of situation.
The picture below shows an
electric infrared panel used in an operating theatre.
Electric infrared panels
are also appropriate to use for supplementary heating over workstations such as
a production line in a factory as shown below.
Electric infrared panels
provide effective protection against cold draughts. The panels emit long-wave
heat rays and maximum heating element temperatures of 100ºC, which means that
the air temperature in the room can be lowered while maintaining comfort and
obtaining lower heating costs.
The problem of cold
draughts from, for example, large window surfaces is effectively counteracted
with Electric infrared panels.
Disadvantages
using Electric infrared panels
The infrared panels are
usually quiet and expensive to install which a client may not want.
As infrared panels are run
via electricity their installation applications are limited for example
Infrared panels cannot be installed where a lot of moisture/water is present,
like a swimming pool.
This can be very dangerous
in a school application because it pupils can get access and touch the panel it
will cause serious burning to the skin or if the waterways within the panel
leak in a class room this can again cause serious burning.
If Electric infrared panels
are used in a factory situation and installed at lower levels than the roof
this can inhibit the maximum working height for the machinery within the
factory.
In an engineering
application where cranes are used this will cause all sorts of problems.
4) Fan
Convectors
Advantages
using Fan Convectors
Fan convectors can be
easily concealed into a wall, therefore leaving all wall spaces free.
Fan convectors have very
good control and can maintain a constant room temperature possibly better than
any of its rivals. Fan convectors can react quickly to a change room
temperature conditions by diverting the flow of water from the coil to the
return in the pipework; this in turn will stop any heat coming from the fan
convector and provides maximum control.
Fan convectors are very
effective when heating a large area as they produce forced hot air into a room.
It distributes the air quickly and effectively and is ideally used in a sports
hall application where the fan convectors can be concealed within a wall and
still produce forced air to heat the space required.
Disadvantages
using Fan Convectors
Fan convectors tend to be
noisy in their general running and therefore wouldn’t be suited to office or
libraries.
A fan convector requires a
lot of maintenance regards cleaning of filters and cleaning of motors. As fan
convectors draw in the air it can also draw in dust to the filter and motor
which causes long term problems.
Fan convectors are not as
cost effective as a radiator for example. The fan convector can be some 500%
dearer to buy than a radiator and as a fan convector uses electricity to run
the fan motor dearer to run as well.
5) Floor
standing unit heaters
Advantages
using Floor standing unit heaters
Floor standing unit heaters
are an ideal method of heat transfer in a large factory or warehouse, as they
can generate heat by direct firing very quickly.
A 2000 m3 area
of space could be heated to its design temperature in about 10 minutes.
Floor standing heaters take
very little maintenance, only a service once a year, and as the unit is floor
standing it is readily accessible and easy to work at if a problem did occur.
Disadvantages
using Floor standing unit heaters
As the installation of a
unit heater tends to be in a factory installation, the unit heater can get
damaged by forklifts and moving machinery which have and adverse effect on the
life expectancy of a unit heater.
Floor standing unit heaters
especially direct fired units are very noisy and tend not to be used in any
other installations apart from factories and warehouses which is a limitation
on the use of the plant.
Unit heaters are a very
permanent job and if you decide to change the layout of the factory and you
want to move the unit heater it can be a major job.