[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [EnergyPlus_Support] Manually sizing baseboards and plant loops
Are you using a variable-speed or constant-speed pump?
avdbree wrote:
>
> I am investigating an existing building. The idea is to add insulation
> and keep the existing baseboards. So, the (new) heating can work with
> a lower supply temperature.
>
> When I autosize maximum (water) flow rates and/or UA-factors in the
> objects ZoneHVAC:Baseboard:Convective:Water, Boiler:HotWater and
> PlantLoop, I get a Delta T of the HW-loop up to 15 °K (which is fine).
>
> Then I set myself maximum water flow rates for the baseboards (based
> on the maximum heating rates from a simulation), while keeping the
> flows of Boiler:HotWater and PlantLoop autosized. Delta T of the
> HW-loop dropped to about 3 °K (which is to small). The results for the
> Zone Mean Air Temperatures and Baseboard Heating Rates are still fine
> (and similar to the autosized situation). Apparently, the flow in the
> HW-loop is quite big now and most of the flow during most of the time
> is going through the bypass on the demand-side of the HW-loop. This
> increases the return temperature and decreases Delta T. A small Delta
> T is not economic.
>
> The occuring maximum loop flow in the HW-loop is exactly the sum of
> all maximum water flows of all the baseboards (as specified in the
> object ZoneHVAC:Baseboard:Convective:Water). So, I tried to set myself
> a lower Maximum Loop Flow Rate of the Plant:Loop (in order to lower
> the bypassed flow and thus increasing Delta T). I choose the maximum
> sum of all the baseboards water flows AT ANY GIVEN MOMENT. This
> maximum is -- in my case-- less then half of the sum of all
> (non-simultaneously) maximum water flows. And, by the way, about twice
> as much as for the completely autosized situation.
>
> But even when I manually set the Maximum Loop Flow Rate of the
> Plant:Loop, the occuring flow in the HW-loop is still the (much
> higher) sum of all (non-simultaneously) maximum flows of all baseboards.
>
> Did I forgot to change another object too or is this a bug?
>
> PS. I tried to attach the idf-file but could not find the way to do this.
>
>
--
Richard A. Raustad
Senior Research Engineer
Florida Solar Energy Center
University of Central Florida
1679 Clearlake Road
Cocoa, FL 32922-5703
Phone: (321) 638-1454
Fax: (321) 638-1439 or 1010
Visit our web site at: http://www.fsec.ucf.edu
UCF - From Promise to Prominence: Celebrating 40 Years
------------------------------------
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/