Sorry but you've taken into account the variation of the heat emission of
radiators according to temperatures?
The heat emission can vary considerably when the heating system operates at
different temperatures to normal considered in calculations (t = 50 ° C).
T (input) = inlet temperature
T (output) = outlet temperature
Tm = average radiator temperature
Ta = ambient temperature.
The difference between the inlet temperature and outlet for a
certain
temperature environment, it is fundamental characteristic at the time of
calculating thermal jump (DeltaT) from a radiator, but must be taken into
account:
DeltaT = radiator thermal break
DeltaT (output) = T (output) - Ta
DeltaT (input) = T (input) - Ta
When:
(Exit) DeltaT / T
(imput) > = 0.7
DeltaT = (DeltaT (output) + DeltaT (input)) / 2)-Ta
But when:
DeltaT (output) / DeltaT (input) < 0.7
DeltaT = (DeltaT (output) - DeltaT (input)) / (Ln (DeltaT (input) /
DeltaT (output))
In your case the difference between
the ambient temperature and the temperature of the radiator (thermal break) is: DeltaT= 55.50ºC
Sorry for my bad English
De: ooodard <povery@xxxxxxxx>
Para: EnergyPlus_Support@xxxxxxxxxxxxxxx
Enviado: Viernes 21 de junio de 2013 15:59
Asunto: [EnergyPlus_Support] Re: European radiators, EN442, baseboard rating
Thanks Jean marais
I am modelling an existing building and need to put in a capacity in watts, not have E+ size the capacity. That way, if the installed radiator is too small, E+ will reveal this.
The EU and US rating methods are both simplifications and E+ simplifies what proportion of output is radiative and convective. The EU method states that the following 2 conditions have the same output.
Room at 15C
Supply at 70 C
Return at 60 C
Room at 25
Supply at 80 C
Return at 70 C
In both cases the difference between average water temperature and room air temperature is 50C.