[EnergyPlus_Support] Re: Heated floor with recirculation

["Jean marais" <jeannieboef@xxxxxxxxx>]

Thanks Brent. I do remember that it is modeled with its own secondary loop. I've not checked the constant flow version for about a year. Can you set the "secondary loop" supply water temp? The systems I deal with in the field are variable mass flow, constant inlet water temp. I assume the constant flow model will have a variable inlet water temp.

The way I look at it is the surface temp is actually the variable that you want to look at. A too hot floor will burn your feet (or create that feet to head temp variation which apparently is not comfortable), and a too cold surface will condensate.

All the systems which exist in eplus also exist in life. Your situation may require the constant flow version. Variable flow is probably more difficalt in some respects and easier in others. I would advise reporting the surface temps and fluid velocities in the pipes to keep things as realistic as you can. Otherwise, you won't find the problem areas of your design.

keep us posted how you get on.  

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Griffith, Brent" <brent.griffith@...> wrote:
>
> Actually the model for the ZoneHVAC:LowTemperatureRadiant:ConstantFlow object essentially has its own little secondary loop built into it. So it can handle hotter or colder primary supply temperatures well.
> 
> 
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of jeannieboef
> Sent: Monday, September 24, 2012 9:58 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: Re: [EnergyPlus_Support] Re: Heated floor with recirculation
> 
> 
> im the way you suggest (direct coupling) the entry water temp will be quite high/cool resulting in more extreme surface temps when extreme heating or cooling loads are present. This will artificially inflate the surface limited heattransfere capabillity of the system. Additionally, condensation cases for the cooling case will not be well represented.
> 
> Sent from my iPhone
> 
> On 24.09.2012, at 15:17, Vaibhav Jain <vaibhav.energyarchitect@...<mailto:vaibhav.energyarchitect@...>> wrote:
> 
> 
> Jean: How about ZoneHVAC:LowTemperatureRadiant:ConstantFlow for radiant floor with re-circulation? Water heaters can be coupled to plant loop.
> 
> Vaibhav Jain
> www.vaibhavjain.co<http://www.vaibhavjain.co>
> 
> 
> 
> On 24 September 2012 14:42, Jean marais <jeannieboef@...<mailto:jeannieboef@...>> wrote:
> 
> 
> This is the next level in eplus expertise...welcome to the club.
> 
> In my opinion, using the waterheater:mixed object as a plate-water-water heatexchanger is the easiest methode. The low-temp loop then is supplied by this tank.
> 
> The concept is that the tank is a user (demand side) on the boiler demandside loop, but at the same time a source (source side) for the low-temp loop.
> 
> Try get this to work with a simple 2 zone model, before expanding to the real building model.
> 
> Goodluck.
> 
> Jean Marais
> 
> 
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx<mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx>, "FrancescoP" <direzionecontraria@<mailto:direzionecontraria@>> wrote:
> >
> > I have posted an image from the design drawings of the plant that I'm modelling: http://imageshack.us/a/img585/41/hotwaterloop.jpg
> > In the plat there are both water radiators and heated floors. The supply temperature of the heated floors is lower than the supply temperature of the water radiator, although the boiler is the same. In fact, the heated floors have a specific secondary loop with water recirculation. What is the best solution to model such a configuration?
> > I start modelling in DesignBuilder and then I develop the model in EnergyPlus.
> > With Regards
> > Francesco Passerini
> >
>




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