[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

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

Hi Overy

I have had the same problem in one of my models.
To my understanding you should input the "test conditions" of any baseboard, and then E+ will calculate the rest according with flow, temperature difference etc etc. 

In an EU context you have the rated power but it is very difficult to find out the "rated flow" under test conditions but you can't find it in laboratory. Here it comes the first problem: which flow? to input...if you look at the I/O Manual, it says "you should input 0.063 Kg/sec...etc, but there is no more reasoning behind this. I assume this is the standard test conditions in the US (???).

Looking at the EN 442 test procedures it states that the mass flow should remain constat during the test but there is no suggestion with regards to which flow rate is the standard etc. To my understanding it may be any flow. The problem is finding the test conditions in the reports (which I find difficult).

Contacting one of the major manufacturers in UK and Ireland also proved fruitless.

Has anyone come across this before?

Regards
Luis

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "ooodard" <povery@...> 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.
>




------------------------------------

Primary EnergyPlus support is found at:
http://energyplus.helpserve.com or send a message to energyplus-support@xxxxxxxx

The primary EnergyPlus web site is found at:
http://www.energyplus.gov

The group web site is:
http://groups.yahoo.com/group/EnergyPlus_Support/

Attachments are currently allowed but be mindful that not everyone has a high speed connection.  Limit attachments to small files.

EnergyPlus Documentation is searchable.  Open EPlusMainMenu.pdf under the Documentation link and press the "search" button.
Yahoo! Groups Links

<*> To visit your group on the web, go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/

<*> Your email settings:
    Individual Email | Traditional

<*> To change settings online go to:
    http://groups.yahoo.com/group/EnergyPlus_Support/join
    (Yahoo! ID required)

<*> To change settings via email:
    EnergyPlus_Support-digest@xxxxxxxxxxxxxxx 
    EnergyPlus_Support-fullfeatured@xxxxxxxxxxxxxxx

<*> To unsubscribe from this group, send an email to:
    EnergyPlus_Support-unsubscribe@xxxxxxxxxxxxxxx

<*> Your use of Yahoo! Groups is subject to:
    http://docs.yahoo.com/info/terms/