Stelrad - Fit for the Future - Catalog - Page 15
Example 1
A typical gas condensing boiler
used with panel radiators.
Room
temperature
20 deg. C.
Mean water
temperature
70 deg. C.
80 deg. C.
The significance
of temperature
difference on
radiators
The temperature difference between the heat emitter
( in this case a radiator ) and the the room temperature is
known as the Delta t.
The examples opposite show the difference between a
conventional heating system and a low temperature system
and how this alters the Delta t.
Delta t
(temperature difference)
50 deg. C.
60 deg. C.
Water is supplied by the boiler to the radiator at 80 deg. C which cools as it passes through the
radiator to 60 deg. C. The average (or mean) temperature of the radiator is therefore 70 deg. C.
The air temperature in the living space is 20 deg. C – therefore the temperature difference
between the radiator (heated to 70 deg. C) and the living space is 50 deg. C.
This is known as Delta (meaning temperature change) t (meaning temperature).
Delta t = 50 deg. C
Example 2
Low temperature heating system
with heat pump as source
Room
temperature
20 deg. C.
Mean water
temperature
42.5 deg. C.
45 deg. C.
Delta t
(temperature difference)
22.5 deg. C.
40 deg. C.
Water is supplied by the heat pump to the radiator at 45 deg. C which cools as it passes through the
radiator to 40 deg. C. The average (or mean) temperature of the radiator is therefore 42.5 deg. C.
The air temperature in the living space is 20 deg. C – therefore the temperature difference between
the radiator (heated to 42.5 deg. C) and the living space is 22.5 deg. C.
Delta t = 22.5 deg. C.
Heat pumps and how they are designed to work in different systems vary. This means that the flow
temperature (inlet to the radiator) can be different to the 45 deg. C shown above. However, it is
always significantly lower (at least 25 deg. C) than that of a boiler.
Ready for the future. Today.
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