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

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.

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.Ã¯Â¿Â½
> >
>