[EnergyPlus_Support] Re: Example of Unitary in series with HW coil

["Jean marais" <jeannieboef@xxxxxxxxx>]

Dear James,

My first mistake was to assume the night manager only comes on at night. Due to the minimum cycle time I had set for it, I was finding my heating coil turning on when it shouldn't be during occupied hours. I've fixed the schedules and cycling time of the night manager.

The second major improvement came when I set the minimum temperature of the heating setpoint manager to -99 C as apposed to 14 C. Looking at node temperatures, the actual air temperatures at nodes never drop below 16 C even off the dx coil, and I eliminate the heating coil turning on during cooling.

At one point I even wrote an EMS to force the heating coil off after zone temps of 21 C, but this only comes into play if heating SP manager low temp is set to 14.

I have a mixed air manager, but noeconomizer set in the unitary dx object. To keep the fan together with the dx coil and the possibility of using an economizer, I use the heatcool object and set the furnace coil availibility to always-0. I substituted this for a cool only arrangement with seperate fan, which showed no differances in performance 
in the zone. I've deleted this object with no effect. 

I have hybrid ventilation set to be discoupled from HVAC. It does not override HVAC systems.

Sizing:Parameters I check by setting it to 10,10 as opossed to 1.25,1.15 for heating and cooling sizing, everytime I make an improvement. No effect (only very marginal)...so I can't improve things here.

At the moment, my coils don't fight each other, and it looks like the dx coil is a bit erradic on it's electric consumption when it's turned on, but increasing it's cycle time has had no effect. I output node temps at all nodes of air loop.

I have surface temperature convergence errors and hvac solver errors. 

And my hair is starting to fall out :)

My next step is to run the hvac set up in my non-stripdown model (which doesn't have these last errors) and see what happens, but it takes long to run so I avoid it if I can as long as possible.







--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "James V Dirkes II, PE" <jim@...> wrote:
>
> Dear Jean,
> 
>  
> 
> Unmet load hours, in my experience , are not improved by adjusting setpoint
> managers.  Rather, I have found that these are more likely to cause unmet
> loads:
> 
> .         A setpoint manager or schedule is not active (it's off or
> incorrectly specified)
> 
> .         The system or zone sizing factor is too low (or high)
> 
> Always, I report many nodes for air loops to see what component is not
> working properly.  I recommend the same for you!
> 
>  
> 
>  
> 
> The Building Performance Team
> James V. Dirkes II, P.E., LEED AP
> 1631 Acacia Drive NW
> Grand Rapids, MI 49504
> 616 450 8653
> 
>  
> 
> From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx] On Behalf Of Jean marais
> Sent: Wednesday, March 30, 2011 2:57 AM
> To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> Subject: [EnergyPlus_Support] Re: Example of Unitary in series with HW coil
> 
>  
> 
>   
> 
> 
> Thanks James,
> 
> The file simulates just Great (thanks for remembering the coil schedule
> needs to be turned on). In my model I'm playing with setpoint managers to
> get rid of the unmet setpoint hours. your example has zero for cooling which
> is exactly where I struggle (even with my weather file). It's a good base
> for comparison.
> 
> Thanks again.
> 
> Jean
> 
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> , "James V Dirkes II, PE"
> <jim@> wrote:
> >
> > Dear Jean,
> > 
> > 
> > 
> > I think that certain of the Unitary objects are restricted to the type of
> > heating coil . and hot water is not allowed for all of them. I've attached
> > a file that works but has not been fully tested. It's for a church and the
> > system you should look at is for the "Sanctuary" zone.
> > 
> > 
> > 
> > p.s., I think attachments are allowed, but if not I'll send it to the E+
> > Files location
> > 
> > 
> > 
> > The Building Performance Team
> > James V. Dirkes II, P.E., LEED AP
> > 1631 Acacia Drive NW
> > Grand Rapids, MI 49504
> > 616 450 8653
> > 
> > 
> > 
> > From: EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> 
> > [mailto:EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> ] On Behalf Of Jean marais
> > Sent: Saturday, March 26, 2011 10:55 AM
> > To: EnergyPlus_Support@xxxxxxxxxxxxxxx
> <mailto:EnergyPlus_Support%40yahoogroups.com> 
> > Subject: [EnergyPlus_Support] Example of Unitary in series with HW coil
> > 
> > 
> > 
> > 
> > 
> > Anybody have a working example of a dx coil and fan wrapped in a Unitary
> > object in series with HW coil?
> >
>




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