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[EnergyPlus_Support] Re: European radiators, EN442, baseboard rating

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "ooodard"  wrote:
>
> I have a typical european radiator which I am modelling in an existing
building.  I don't want E+ to autosize anything.
>
> Flow temp=82 C
> Return temp notionally 71 C
> Radiator output according to EN442= 1.4 kW
>
> Boilers are delivering 82 C water.
>
> How do I model that?
>
> I am using Baseboard:RadiantConvective:Water
>
> E+ rating is based on US baseboard rating methods, which, I read,
assume a rating zone air temperature of 65 F (18.3 C).  EN442 in Europe
on the other hand assumes a 50C temperature difference between room air
and average water temperature i.e. it is independent of room air
temperature.  Combining the two to convert my European rating to US, see
below:
>
> Is this correct?
> Rated Average Water Temperature=18.3+50=68.3 C,
> Rated Water Mass Flow Rate=q/(Cp*Delta T)=1.4/(4.2*11)=.03 kg/s
> Rated Capacity =1400 W
> Maximum Water Flow Rate=1.4/(4.2*11)=0.03 kg/s=0.00003 m3/s
>
> The wording in the I-O Reference Manual for "Rated Capacity" is
> "This field is the rated water baseboard capacity in watts at a rated
water mass flow rate. Almost all publications from manufacturers
indicate it as W/m (Btuh per linear foot). The user thus must multiply
it by the active length of the unit. The active length is
> available in the literature. Manufacturers are required to publish the
difference between active and total length of the unit (I=B=R rating for
boilers baseboard radiation, 2009). This field can
> be autosized by EnergyPlus. If it is blank or zero, autosizing is
assumed."
>
> Not very clear.
>
> I can only get sensible answers if I increase the Maximum Water Flow
Rate to several times the above calculated figure.
>
> Any advice would be most appreciated.
>




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