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[EnergyPlus_Support] Re: EMS temperature control
Thank you for your reply.
There are two energy inputs in my heating loop. Energy is input into the HPWH Coil and secondly there is electrical input to drive the heating loop circulation pump. The 12kW electric heater was not meant for frequent use but rather times when the heat pump needed additional energy to raise the temperature.
I was attempting to just disable the heating loop when the room temperature went above a certain value. After studying example 10 I have decided to disable both the heating loop circulation pump and also turn off the loop. The application guide suggest that skipping either of these can cause mis-matches and flow errors. I have also raised the thermostat set point to ensure it is not interfering with the EMS. It seems to be responding to the EMS program now.
Kindest Regards,
John Kirby
--- In EnergyPlus_Support@xxxxxxxxxxxxxxx, Richard Raustad <RRaustad@...> wrote:
>
> Very nice drawing.
>
> The heat pump water heater already has a deadband, but of course this is
> not based on zone temperatures, but a fixed schedule. The mixed water
> heater also has a schedule and a deadband, and if the water temperature
> falls below the tank's schedule value minus the deadband, the 12kW
> electric heater will turn on in the tank.
>
> WaterHeater:HeatPump,
> Heat Pump Water Heater Plant, !- Name
> HP on/off, !- Availability Schedule Name
> HPWH HW SP AN, !- Compressor Setpoint Temperature
> Schedule Name
> 2.0, !- Dead Band Temperature Difference {deltaC}
>
> WaterHeater:Mixed,
> HPWH Tank, !- Name
> 0.00379, !- Tank Volume {m3}
> HPWH TANK HW SP AN, !- Setpoint Temperature Schedule Name
> 2.0, !- Deadband Temperature Difference {deltaC}
>
> Since you do not have report variables for the mixed water heater in
> your input file, I wonder if you actually know what is heating the tank.
> What is the tank temperature? Is it 55? or 60? Your actually not
> reporting anything of value and do not know what is happening in your
> simulation. How can you possibly debug your simulation?
>
> In addition, how is the zone temperature going to rise above the set
> point when you still have hot water in the tank. The baseboards will
> continue to supply heating to the zones until the tank temperature falls
> to some low temperature. After that the zone temperature will rise, and
> THEN you want your HPWH to turn on?
>
> The first thing I would do is add more report variables (see the rdd
> file) to see what is happening.
> The next this I would do is disable the electric element in the tank
> (set it to 0kW) if your tricking the HPWH to act on EMS programming. You
> could also control the tank hot water temp schedule with the EMS if you
> didn't want to disable the electric element (set it very low until you
> want the electric element to turn on).
>
> P.S. most users on this yahoo site will not or can not help you with
> more complex input files. This question is more geared towards an
> Energyplus Helpdesk question. But do your homework before asking for
> help from that site. If you send this same email and input file to that
> site without modification, I will give you the same answer I gave you
> here. Add more report variables and try to figure out what is happening
> with your simulation.
>
> To access the help desk, send your email and input file to:
>
> energyplus-support@... or go to http://energyplus.helpserve.com/
>
>
> On 2/24/2011 1:09 PM, John Kirby wrote:
> >
> > Hi.
> >
> > I am using EMS to control the on/off status of a heat pump. I have
> > sensors for each Zone Mean Air Temperature. I also have a sensor for
> > the heating setpoint defined in the schedules(It is set @ 22 degrees
> > for each period ) .The Zone Mean Air Temperature output variable of
> > Zone3 is being compared against the heating setpoint to decide whether
> > or not to turn the heat pump on.
> >
> > The program defines the turn on point as the heating setpoint, and the
> > turn off point as the heating setpoint + Toffset. The actuator is set
> > up so for on/off supervisor control to actuate the heating loop.
> >
> > The program is having no influence on the output temperatures. The EDD
> > file suggests that the program recognizes the heating setpoint (
> > 22 and 24). I am confident that the Actuator is set up correctly but
> > results suggest that it is not doing what it is meant to do.
> >
> > It is a very simple program, but after discussing with a colleague
> > over the last couple of days we have been unable to get it to work. I
> > attached the idf file. I have also attached a diagram of the heating
> > loop being used. If anyone has any suggestions I thank you in advance.
> >
> > Kindest Regards
> >
> > John Kirby
> >
> >
> >
>
> --
> 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
>
> UCF - From Promise to Prominence: Celebrating 40 Years
>
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