RE: [EnergyPlus_Support] Re: Setting the HVAC ON/OFF cycle

Hi, Aditya

There are 12 day types. You have missed out 2, usually can cover them with 'AllotherDays'.
These are the cause of the warnings in your error file. Zero are used for all the un-resolved cases.

10 and 9 in the CSV shows you that I was using the DesignDay simulation.

If you do not turn on the daytype index, you do not know which day you are working on.
============================
Schedule:Compact,
Htg-SetP-Sch, !- Name
Temperature, !- Schedule Type Limits Name
Through: 12/31, !- Field 1
For: Weekdays , !- Field 2
Until: 8:00, 21, !- Field 4
Until: 15:00, 15, !- Field 6
Until: 24:00, 21, !- Field 8
For: Weekends Holidays, !- Field 9
Until: 10:00, 21, !- Field 11
Until 16:00, !- Field 12
15, !- Field 13
Until: 24:00, 21, !- Field 15
For: SummerDesignDay, !- Field 16
Until: 24:00, 15, !- Field 18
For: WinterDesignDay, !- Field 19
Until: 24:00, 21; !- Field 21

These may not be the numbers you wanted in real situation. Because of the dead band requirement cooling and heating should not cross over.
In the schedule below, you are cooling more at night.

Schedule:Compact,
Clg-SetP-Sch, !- Name
Temperature, !- Schedule Type Limits Name
Through: 12/31, !- Field 1
For: Weekdays, !- Field 2
Until: 8:00, 23, !- Field 4
Until: 15:00, 28, !- Field 6
Until: 24:00, 23, !- Field 8
For: Weekends Holidays, !- Field 9
Until: 10:00, 23, !- Field 11
Until: 16:00, 28, !- Field 13
Until: 24:00, 23, !- Field 15
For: SummerDesignDay, !- Field 16
Until: 24:00, 23, !- Field 18
For: WinterDesignDay, !- Field 19
until: 24:00, 28; !- Field 21
========================
Make the schedules simple, for example.

Schedule:Compact,
CoolingSetPoint-Sch, !- Name
Temperature, !- Schedule Type Limits Name
Through: 12/31, !- Field 1
For: SummerDesignDay AllOtherDays, !- Field 2
Until: 06:00, 30,
Until: 08:00, 25,
Until: 18:00, 24,
Until: 24:00, 30;

Schedule:Compact,
HeatngSetPoint-Sch, !- Name
Temperature, !- Schedule Type Limits Name
Through: 12/31, !- Field 1
For: WinterDesignDay AllOtherDays, !- Field 2
Until: 06:00, 10,
Until: 08:00, 15,
Until: 18:00, 20,
Until: 24:00, 10;

If you run the file with the above schedules, you will see more variations.
Generally the following will be sufficient for the debugging stage.

WinterDesignday allotherdays (heating)
SummerDesignday allotherdays (Cooling)

Combined with the type4 thermostat, you will be able to see the temperature changing.
======

The zone temperature will change, instead of one fixed value.
DesignDays should be the same as weekdays., unless you have special indoor occupancy equirements.

If you choose constant fan, the fan will not turn off. If you choose on/off fan, the fan will turn off with the compressor when the zone temperature is in the dead band.

I have not changed the schedules in your file, but has added some request for diagnostics.
and variables.

I will change the IDF for you, if you will let me know which item in the warning is still un-resolved.
====================

Then when the temp drop by 1deg C below the set point, the heating should start again, i.e. FAN is ON now until the set point is reached.

There is a set back value in type4 thermostat. I do not know the exact value. At 10 mins intervalve, the averaged value varies by 0.002 degree.

=================

Dr. Li

To: EnergyPlus_Support@xxxxxxxxxxxxxxx
From: adityaravi87@xxxxxxxxx
Date: Thu, 4 Aug 2011 15:52:03 -0700
Subject: Re: [EnergyPlus_Support] Re: Setting the HVAC ON/OFF cycle

Hello,

I have attached my input idf file with the email. Please go through it. I am not able to understand if I am covering all necessary inputs on E+. Every time I open a new example file, I see diff information and hence I am getting worried as to whether I have covered all necessary inputs. Below pasted is what I am trying to achieve. If you can suggest on how I should develop my input file, so that I get my output for the ZONE?TEMP as per the description and see a HVAC ON/OFF cycle as a result it will be of great help.

FOr Winter when heating:

IF ZONE/SYS TEMP = HEATING_SETPOINT

HVAC = OFF

IF ZONE/SYS TEMP = HEATING_SETPOINT - 1 Deg C

HVAC = ON

Similarly for Summer, when cooling:

IF ZONE/SYS TEMP = COOLING_SETPOINT

HVAC = OFF

IF ZONE/SYS TEMP = COOLING_SETPOINT + 1 deg C

HVAC = ON

These are controlled by the thermostat cooling and heating setpoint schedules.

I am using PTAC with electric HEATING COIL and a SINGLE DX COOLING COIL. I have designed my own house using SKetchup. I am considering the entire house to be a single zone since only one thermostat is being used and hence uniform temp for the entire house.

You should partition the building so that you can study the shading that can be provided on the windows to cool the building.

From: Aditya <adityaravi87@xxxxxxxxx>
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Sent: Thursday, August 4, 2011 6:08 PM
Subject: [EnergyPlus_Support] Re: Setting the HVAC ON/OFF cycle

Hello,

Thank you for the tip. However, through the sensible heating or cooling energy I am able to understand the points where the fan is ON/OFF. What I need is to program my inputs such that once the set point is reached the FAN/Compressor should cut OFF. Then when the temp drop by 1deg C below the set point, the heating should start again, i.e. FAN is ON now until the set point is reached.

In an earlier email I was told that as long as the load is there, the heating or cooling will continue, and it does not matter if the set point is reached as indicated in the ZONE TEMP. So I checked for the part load ratio which tell me how long the fan was ON for the given time step. Is there a another way in which I can enter my inputs to make the HVAC work in a ON/OFF cycle such that the ZONE TEMP varies between the set point and setpoint - 1 deg C for Winter/HEATING and between SETPOINT and SETPOINT + 1deg C for SUMMER/COOLING

Kindly help to create such a input program.

--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, "Jean marais" <jeannieboef@...> wrote:
>
> Check your rdd file for the right variable to report. I believe you can report the fan electric consumption (which will be null if the fan is off) as well as the entire airloop status on/off, as well as coil water flow, and so on. To generate the rdd file you must have
>
> Output:VariableDictionary, Regular;
>
> somewhere in the idf
>
> --- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Aditya Ravi <adityaravi87@> wrote:
> >
> > When we run E+ and adjust the time step, which time step are we changing. I need to know how long HVAC is ON or OFF. I was suggested to find the part load ratio. However if I want to vary the system(HVAC -PTAC) time step what do I need to do. Also I have asked this earlier, but is there way where we can show the system switching ON/OFF as the set point is reached. By this I mean, showing the cycles when the system is ON, and OFF. Say if the system is ON, it cools the room to the set point in Summer or heats the room to the set point in Winter.Then on reaching a set point system(HVAC) goes OFF until the room/zone temp say rises by 1deg C above the set point for summer or Zone temp drop by 1deg C below the set point in Winter. And finally again switching. I need to know how I can achieve this kind of cycle in my output.ï¿½
> >
>

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