Key differences: Radiant Vs convection heat
Radiant heat warms objects and surfaces without heating the air in between.
Those objects warm up directly and radiate back.
Convection warms the air, which is a triple inefficiency. The air has to:
Warm up. Air absorbs heat poorly;
 Travel (unforced convection of heat is always upwards to the ceiling or
through doors and windows. Only forced convection – using a fan – convects
heat horizontally );
 Deliver the heat to something. Air transfers heat out poorly;
Degree for degree °F, radiant heat delivers the heat transfer capability of
convection to the power of 4 (Boltzmann’s law).
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CONVECTION
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Heat exchange has to occur twice (indirect heating of objects)
Air absorbs & retains heat poorly
Hot air rises and is prone to infiltration loss (draughts)
Air heats thermal mass poorly, so when the heating stops, so does the
warmth.
RADIANCE
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Heat exchange occurs once (direct heating of objects)
Most domestic materials absorb & retain heat well
Less prone to infiltration loss in an enclosed space
Excellent priming of thermal mass = when heating stops, residual heat is left
in the building.
Advantages for heaters
The advantages of radiant heating over convection:
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Heat transferred (watts / foot / second) grows exponentially with
temperature rise. Convection heat transfer grows only linearly with
temperature.
You require less installed capacity in a radiant heating system
You don’t need to run it as long
You can apply heat only where you need it – you don’t need to heat the
whole room
You can control it more precisely
Types of radiant heaters from Herschel
Herschel Infrared supplies
Far Infrared Panels – these are mostly used in residential and office applications.
Far Infrared Space Heaters – for heating larger enclosed or sheltered outdoor
spaces
Medium Infrared Space Heaters – for heating unsheltered areas (e.g. patios) or
colder indoor areas.