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2021-11-16 01:22:47 -0600 marked best answer Water condenser low temperature, chiller heat recovery

Hi, I'm trying to model a chiller with heat recovery, for DHW purposes.

I'm using a Chiller:Electric:EIR connected to a WaterHeater:Mixed. The model is running but I get a very low water temperature from the chiller condenser. Basically the water going into the tank water heater is decreasing its temperature since the inlet water temperature goes from 30°C to 20°C.

How can I get an higher temperature from the chiller condenser? Did anyone have the same issue?

I found something here: https://unmethours.com/question/19434...

Thank you in advance

2021-08-02 11:04:17 -0600 received badge  Self-Learner (source)
2021-05-30 05:14:52 -0600 received badge  Popular Question (source)
2021-05-12 16:28:25 -0600 marked best answer Run EnergyPlus in Matlab

I'm trying to run EnergyPlus in Matlab. I found mle+ but I could only find guides for the GUI.

Since I have to run many simulations with data previously calculated in a Matlab script, it could be easier to run E+ directly inside a loop statement.

I found out how to do in python (https://unmethours.com/question/22157...) but I couldn't find it in Matlab.

Thank you!

2021-03-09 02:04:56 -0600 received badge  Popular Question (source)
2020-08-26 16:59:19 -0600 marked best answer Elements - Normal Solar versus Direct Normal Radiation

I'm trying to use Element software to create new weather files.

Now i have some doubts about the outputs: it gives me back the "Normal Solar" instead of the "Direct normal Radiation" that E+ should demand.

Am I wrong?

I couldn't find a way to force this variable because it's related to the "Global solar" and to the "Diffuse solar" through an equation. Therefore I can't set all three variables: one is auto-calculated.

image description

2020-03-27 20:19:49 -0600 received badge  Popular Question (source)
2020-01-29 07:56:12 -0600 commented question Optical depths for the ASHRAE Clear Sky Model

Do you need to calculate your own coefficients (from measurements) or you just do not know where to find them?

2020-01-27 18:42:25 -0600 marked best answer Python Eppy, readhtml table

Hi, I'm trying to use eppy to read EnergyPlus html tables.

When I type (as explained here http://pythonhosted.org/eppy/Outputs_... ):

from eppy.results import readhtml

I get the following error: "ModuleNotFoundError: No module named 'eppy.results'". I've read here (https://github.com/santoshphilip/eppy...) there's an issue about it: as advised, I installed it with Anaconda prompt:

pip install https://github.com/santoshphilip/eppy/archive/i169_readhtml1.zip

The installation was successful but I get the same error in Python, nothing changed.

Has anyone solved this problem? Could I use another method to read this tables?

2019-10-25 01:43:30 -0600 commented question How to set different working directories for parallel simulations?

I know it is not what you are looking for, but you could run two different python instances pointing two different folde

2019-10-04 09:14:13 -0600 commented answer Energyplus, Design day : date and solar radiation

@eru You are right, if you don't change the air temperatures you could get an oversized result. To solve it, you can use

2019-10-04 09:13:27 -0600 commented answer Energyplus, Design day : date and solar radiation

@eru You are right, if you don't change the air temperatures you could get an oversized result. To solve it, you can use

2019-10-01 12:56:18 -0600 commented answer Energyplus, Design day : date and solar radiation

If you have no idea and if it does not take too long, add 12 "SizingPeriod:DesignDay" objects, one for each month

2019-09-27 04:21:26 -0600 edited answer Energyplus, Design day : date and solar radiation

The solar radiation is not influenced by the weather file: of course it is right to take a look into the weather data to

2019-09-27 04:20:00 -0600 edited answer Energyplus, Design day : date and solar radiation

The solar radiation is not influenced by the weather file: of course it is right to take a look into the weather data to

2019-09-27 01:47:11 -0600 answered a question Energyplus, Design day : date and solar radiation

The solar radiation is not influenced by the weather file: of course it is right to take a look into the weather data to

2019-09-25 08:52:31 -0600 commented question Warmest vs WarmestTemperatureFlow SetpointManager: DCV

I could not replicate the error in a test model: everything looks right during the test. I guess it is something related

2019-09-23 13:45:02 -0600 asked a question Warmest vs WarmestTemperatureFlow SetpointManager: DCV

Warmest vs WarmestTemperatureFlow SetpointManager: DCV My question is related to these specific answers: https://unmetho

2019-09-05 02:33:26 -0600 marked best answer Condenser water flow rate with EMS: EnergyPlus

My question is related to this issue (https://unmethours.com/question/35540... ticket: https://github.com/NREL/EnergyPlus/is...) where the condenser pump is not working as expected.

Is there a way to control the condenser water flow rate with an EMS program? I guess it could be done using the "Chiller Condenser Heat Transfer Rate [W]" output as sensor and a "SetpointManager:Scheduled" as actuator. Unfortunately it is not possible since the condenser loop requires a temperature setpoint.

Is there another way?

2019-09-05 02:32:36 -0600 edited answer Condenser water flow rate with EMS: EnergyPlus

Following the previous answer by Julien Marrec I tried the following: I used the example file "CoolingTower_TwoSpeed"

2019-09-05 02:30:32 -0600 answered a question Condenser water flow rate with EMS: EnergyPlus

Following the previous answer by Julien Marrec I tried the following: I used the example file "CoolingTower_TwoSpeed" R

2019-09-05 02:04:50 -0600 commented answer Condenser water flow rate with EMS: EnergyPlus

I think it works....! Thanks a lot, I'll add the results in another answer below.

2019-09-05 02:04:33 -0600 commented answer Condenser water flow rate with EMS: EnergyPlus

I think it works....! Thanks a lot, I'll add the results in another answer below.

2019-08-30 05:37:28 -0600 commented answer Condenser water flow rate with EMS: EnergyPlus

uh yes, those equations are exactly what I was thinking about: the pump actuator is what I was missing. I guess I will t

2019-08-30 05:36:52 -0600 commented answer Condenser water flow rate with EMS: EnergyPlus

uh yes, those equations are exactly what I was thinking about: the pump actuator is what I was missing. I guess I will t

2019-08-30 05:36:29 -0600 commented answer Condenser water flow rate with EMS: EnergyPlus

uh yes, that equations are exactly what I was thinking about: the pump actuator is what I was missing. I guess I will tr

2019-08-26 08:04:25 -0600 asked a question Condenser water flow rate with EMS: EnergyPlus

Condenser water flow rate with EMS: EnergyPlus My question is related to this issue (https://unmethours.com/question/355

2019-08-26 07:52:11 -0600 commented answer Baseline HVAC system

Yes you are right, my answer was related to the 90.1-2007 that (if I'm not wrong) do not contain any exception based on

2019-08-22 03:48:04 -0600 answered a question Baseline HVAC system

Table G3.1.1A states that if your source is electric (proposed) you have to chose one option in the last column, therefo

2019-08-12 11:12:54 -0600 commented question Water cooling coil design inputs

Same here: all the coils, fan coil and fans are "as designed" and not "autosize"

2019-05-06 10:03:01 -0600 marked best answer LEED Baseline G3.1.2.1: EER and COP with fan energy

Hi, I'm trying to break down the fan power from the System 4 performance. I've read this answer: https://unmethours.com/question/27720...

I use the Ashrae 2007 SI edition and if I use the following data (as an example): Cooling 39 kW (autosize) so I consider a power of 40 kW that is 136486 btu/h Considering the table 6.8.1B I have a COP of 3.16 (as of 1/1/2010)

I apply the formula: 7.8410^-8EERQ+0.338EER = 7.8410^-83.16136486+0.3383.16 = 1.10

So I get a COP of 1,10 that seems very low. Is there a mistake? Is it correct to level up the cooling power to the higher interval (39 kW to 40 kW)?

2019-05-01 13:20:03 -0600 marked best answer VRF with hot water generation, heat exchanger

Hi, I need to model a VRF system with a so called "Hydro Box". It is a plate heat exchanger that allow to generate hot water that can be used both for heating demand (ie heated floor) and for DHW demand. Therefore the system can produce heating with hot water AND with direct expansion coils (split).

I specify that this approach is considered in heating mode, so it's not related to a heat recovery during cooling (that I know it can be modeled).

So my question is: is there a way to model a condenser based on a "refrigerant to water heat exchanger"?

Thank you

2019-04-25 08:44:28 -0600 commented answer Appendix G Cooling Tower, System 8

Thanks, it works. I'm only concerned about one thing, in the html I get a cooling tower capacity that is almost 50% of t

2019-04-22 02:52:59 -0600 asked a question Appendix G Cooling Tower, System 8

Appendix G Cooling Tower, System 8 Hi, I'm modeling a cooling tower for the baseline building with E+ 8.5. The cooling

2019-04-18 10:57:20 -0600 commented question Water cooling coil design inputs

I have the same problem... I did not know that not using the Sizing:Zone could solve the issue. Maybe also this question

2019-04-18 10:56:52 -0600 commented question Water cooling coil design inputs

I have the same problem... I did not know that not using the Sizing:Zone could solve the issue. Maybe also this question

2019-03-21 11:01:38 -0600 marked best answer Weather file altitude VS building altitude (EnergyPlus)

If the weather file altitude and the building altitude (Site:Location -> Elevation) differs, does E+ automatically apply a correction?

In my case, the objects Site:WeatherStation and Site:HeightVariation are blank.

From what I can read in the documentation, the correction (if set) is applied to altitude variations within the model, for example between ground floor and the attic of a high building. Is it correct?

2018-12-24 01:24:01 -0600 commented answer Ashrae sizing: Zone Sensible Cooling and ZoneHVAC:IdealLoadsAirSystem

Ok, thank you very much

2018-12-19 21:40:02 -0600 marked best answer precipitation: EPW vs Site:Precipitation

Hi, I'm using EnergyPlus.

My question is straightforward: between EPW and the object Site:Precipitation data, which one has the priority? Does the Site:Precipitation object overwrite the EPW data?

Thank you

2018-12-18 13:14:01 -0600 commented answer LEED Occupancy, design data vs ashrae

Great, thank you

2018-12-18 13:09:29 -0600 commented answer LEED Occupancy, design data vs ashrae

Thanks for the deep explanation, I agree with you. More in detail my question was related to the Ashrae peak value vs th

2018-12-15 06:04:10 -0600 marked best answer Ashrae sizing: Zone Sensible Cooling and ZoneHVAC:IdealLoadsAirSystem

Hi, I'm studying ASHRAE 2009 cooling sizing (RESIDENTIAL COOLING AND HEATING LOAD CALCULATIONS Chapter 17) and in my model I'm using an IdealLoad system.

Can I get the sizing results from EnergyPlus? I see two tables that could be useful (in the html file): Zone Sensible Cooling and ZoneHVAC:IdealLoadsAirSystem tables. Is one of these the ASHRAE sizing result?

Referring to the html tables, if I read the table Zone Sensible Cooling it misses the ventilation losses. On the other hand, the ZoneHVAC:IdealLoadsAirSystem gives me very high values (much more than the Zone Sensible Cooling plus the ventilation loss) and I can't find an E+ document where the sizing method is described.