Free Sample
The Complete Handbook of Heating Radiators
For HVAC professionals, facilities managers, and anyone specifying or maintaining heating systems
by Alumigogo Books
Chapter 1: Understanding Heating Radiators
Heating radiators are heat exchangers designed to transfer thermal energy from hot water or steam into the air of a room or space. That simple definition, however, conceals the practical complexity that determines whether a radiator will heat your building efficiently, last for decades, or fail prematurely.
A radiator sits at the end of a chain of decisions: the fuel source (natural gas, oil, heat pump, district heating), the boiler or heating plant that raises that fuel's energy into hot water or steam, the distribution pipes that carry that thermal energy, and finally the radiator itself, which releases that energy into the room. If any part of that chain is mismatched to the others, the radiator—even if it's well-made—will underperform.
How a Radiator Actually Works
A radiator transfers heat through two mechanisms: radiation and convection. The name "radiator" is somewhat misleading, because most of the heat transfer in a typical modern radiator is actually convective, not radiant.
When hot water enters the radiator's internal passages, it heats the metal. That hot metal surface then transfers energy to the room in two ways. First, the radiator emits infrared radiation—electromagnetic waves that travel through air and warm anything they strike. This accounts for roughly 20 to 40 percent of heat output in most radiators, depending on the radiator type and room geometry. Second, the hot metal surface heats the air immediately around it. That warm air becomes less dense and rises; cooler air sinks in to