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[EnergyPlus_Support] Re: dual setpoint with deadband thermostat/furnace control problems
Thank you very much! I have a few other questions if you've got the
time. I changed the variables you advised, and output an hourly
report for the design days. When looking at the report, there are a
few hours on my summer design day in which the furnace seems to be
heating. I don't understand why this is, considering a) the outdoor
temperature is between 30 and 37C and b) I set a deadband from 20-
25C. To me, this means the heating will not come on unless the
indoor temperature is 20C or below. Am I misunderstanding what the
output "zone/sys sensible heating rate" represents?
Also, when I do an annual run with monthly data, the outputs I'm
looking for are instantaneous sensible and latent cooling loads (as
well as total heating load (which I am mostly familar with in the
units of BTUH) and winter envelope losses and total heating load. I
was under the impression that the "zone sensible load to heating
setpoint predicted" and "zone sensible load to cooling setpoint
predicted" variables represented the total heating and cooling
sensible loads, but the numbers just don't look right to me. 25,000
watts of cooling for an 1800sf building?
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad
<RRaustad@...> wrote:
>
> Change these 2 report variables to hourly and change the run
control
> object to only do the design days.
>
> Report Variable,
> *, !- Key_Value
> Furnace Fan Part-Load Ratio, !- Variable_Name
> timestep; !- Reporting_Frequency
>
> Report Variable,
> *, !- Key_Value
> Furnace Compressor Part-Load Ratio, !- Variable_Name
> timestep; !- Reporting_Frequency
>
>
> RUN CONTROL,
> Yes, !- Do the zone sizing calculation
> Yes, !- Do the system sizing calculation
> Yes, !- Do the plant sizing calculation
> Yes, !- Do the design day simulations
> No; !- Do the weather file simulation
>
> You will see that the simulation is maintaining the set points
> correctly. 20C in winter and 25C in summer just
> as your compact HVAC thermostat requested.
>
> COMPACT HVAC:THERMOSTAT,
> Thermostat, !- Thermostat Name
> , !- Thermostat Heating Setpoint Schedule
> 20.0000005298191, !- Thermostat Constant Heating Setpoint {C}
> , !- Thermostat Cooling Setpoint Schedule
> 25.0000006622738; !- Thermostat Constant Cooling Setpoint {C}
>
> If you make an annual run and see a time when both heating and
cooling
> occur, it is because the simulation ran at a
> reduced time step and you are seeing the average values over the
hour.
> Use a detailed
> time step to see what is happening during these times. Example:
>
> Report Variable,
> *, !- Key_Value
> Furnace Fan Part-Load Ratio, !- Variable_Name
> detailed; !- Reporting_Frequency
>
> Make all your report variables "detailed" so the info lines up in
the
> csv file.
>
> And make the run period smaller to reduce the size of the output
file:
>
> RunPeriod,
> 5, !- Begin Month
> 1, !- Begin Day Of Month
> 7, !- End Month
> 31, !- End Day Of Month
> UseWeatherFile, !- Day Of Week For Start Day
> Yes, !- Use WeatherFile Holidays/Special Days
> Yes, !- Use WeatherFile DaylightSavingPeriod
> No, !- Apply Weekend Holiday Rule
> Yes, !- Use WeatherFile Rain Indicators
> Yes, !- Use WeatherFile Snow Indicators
> 1; !- Number of years of simulation
>
>
>
> darthskunky wrote:
>
> > I'm modeling a fairly simple home that's around 1800 square feet
with
> > a COMPACT HVAC furnace (set up mostly to autosize.) I've been
having
> > trouble figuring out what's going on with the thermostat, which I
> > believe is has a control type of dual setpoint with deadband,
which is
> > what I want. I set the heating to 68 and the cooling to 77.
> > Nevertheless, looking at my hourly data, there seem to be days
when
> > the heating and cooling systems are directly opposing eachother.
> > Would someone be willing to look at my files to see what's going
on?
> > I'm new to EnergyPlus and have been having numerous problems
obtaining
> > anything close to what seem like valid outputs. My input file is
> > pretty simple, so troubleshooting might not be too hard. I'll
upload
> > the files. The idf is called habitatcomposite. If someone could
help,
> > I would be incredibly grateful, as I need to get this figured out
> > pretty soon. Thanks a lot!
> > MC
> >
> >
> >
> >
> >
> >
> >
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>
> --
> 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
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