[TRNSYS-users] Heating Type Manager (Heating Load is too high)

Sat Nov 28 08:15:00 PST 2020

Hello everybody,

thank you a lot for your help. I think I found the problem. My rooms border on a cold outside area and are too small so that the heating load cannot be distributed over the area. Therefore the heating load of these rooms are too high.

But I have another question: Does anyone know how I can control my heating hours? I have set my room temperature as an Input in the Heating Type Manager and control my heating using a calculator in Simulation Studio. With Type 14h I have created a time profile (heating_schedule) for my heating. The heating should be on from 7 a.m. to 6 p.m., but the room should not be heated all the time. It should stop when the required temperature of 20 degrees has been reached. It so happens that I have 11 hours of heating a day, but that's wrong. It should not be heated continuously from 7 a.m. to 6 p.m. When the 20 degrees room temperature is reached, it should actually last a while before heating up again. Does anyone know a logical formula how I can take into account that heating is only started again when the temperature falls below a certain level?

So far I got the following equations in my calculator:

Input1 = heating_schedule
Input2 = Tamb (outside temperature)
on = 1
off = 0
temperature = 20
control = LT(Tamb,15)*on+(1-LT(Tamb,15))*off  // here I have taken into account that heating should only take place when the temperature is lower than 15 degrees
heating = temperature*heating_schedule*control

So far everything works, but how can I take into account in my equation that heating does not take place during the entire period, but after the room temperature drops from 20 degrees.

Thank you in advance for your help.

Kind regards,

Asma

________________________________
Von: David BRADLEY <d.bradley at tess-inc.com>
Gesendet: Freitag, 27. November 2020 10:17
An: Asma Sohail <asma.sohail at hotmail.de>
Betreff: Re: [TRNSYS-users] Heating Type Manager (Heating Load is too high)

Asma,

  I think that without seeing the project there isn't much more that I can guess at. I would recommend that you send the project to your distributor (hotline at transsolar.com<mailto:hotline at transsolar.com>) to see if they can give you some specific help and look over the project for possible causes of the behavior.

kind regards,

 David

On 11/25/2020 18:14, Asma Sohail via TRNSYS-users wrote:
Hello David,

thank you for your hint. I didn't use the Building Wizard. I  only defined my rooms in TRNBuild and then worked with simulation studio. I do not built a 3D-Model or anything.

I took a closer look on the boundary conditions of my ground floors. There is a second floor under my rooms, that should be heatet to 20 degrees. So I selected "identical" as boundary condition, because the rooms underneath should have the same temperature (adiabatic state). I even tried that I set the boundary condition to "userdefined" with an adjacent temperature of 20 degrees. Nevertheless, the heating load of zone 15 and zone 16 didn't change and was the same, so it is still  too high.

Thank you all for your help! I hope that my problem can be solved.

Best regards,

Asma

________________________________
Von: Sohail, Asma <st159047 at stud.uni-stuttgart.de><mailto:st159047 at stud.uni-stuttgart.de>
Gesendet: Mittwoch, 25. November 2020 15:24
An: asma.sohail at hotmail.de<mailto:asma.sohail at hotmail.de> <asma.sohail at hotmail.de><mailto:asma.sohail at hotmail.de>
Betreff: WG: [TRNSYS-users] Heating Type Manager (Heating Load is too high)

________________________________
Von: TRNSYS-usersIm Auftrag vonDavid BRADLEY via TRNSYS-users
Gesendet: Mittwoch, 25. November 2020 11:23:56 (UTC-12:00) Internationale Datumsgrenze West
An: TRNSYS users mailing list at OneBuilding.org
Cc: David BRADLEY; Asma Sohail
Betreff: Re: [TRNSYS-users] Heating Type Manager (Heating Load is too high)

Asma,

 Take a look at the ground floor boundary condition. Depending on whether you used the building wizard or not, the temperature of the ground underneath the slab can default to 0C, which often causes unrealistically high heating loads and unrealistically low cooling loads.

kind regards,

 David

On 11/25/2020 09:52, Asma Sohail via TRNSYS-users wrote:
Hello Christina,

thank you for the quick reply. Yes you're right, I'm converting the Qsens only from kJ/hr to W. I then enter the values in Excel and divide my total heating load from a zone by the zone-area. I have a problem especially with the zone 15 and zone 16. These are interior rooms. An elevator and installation shaft (no heating on) is adjacent to these rooms. The elevator and installation shaft do not fall below a temperature of 15 degrees, so it's impossible that the zone 15 and zone 16 needs that much of heating power I get in the simulation. I even calculated the heat load manually. I don't know why, but I only get for interior zones a heat load that is way to high. There's somewhere a problem, maybe it's an easy problem, but I do not find it. I checked every link and the .b18-file but I do not find it. I also have to say, it's my first time working with TRNSYS. Perhaps the problem is in some setting I did wrong.. I hope really you could help me. Thank you in advance for your time, effort and help.

Best regards,

Asma

________________________________
Von: Sohail, Asma <st159047 at stud.uni-stuttgart.de><mailto:st159047 at stud.uni-stuttgart.de>
Gesendet: Mittwoch, 25. November 2020 07:25
An: asma.sohail at hotmail.de<mailto:asma.sohail at hotmail.de> <asma.sohail at hotmail.de><mailto:asma.sohail at hotmail.de>
Betreff: WG: Heating Type Manager (Heating Load is too high)

________________________________
Von: TRNSYS-usersIm Auftrag vonhotline via TRNSYS-users
Gesendet: Mittwoch, 25. November 2020 03:24:44 (UTC-12:00) Internationale Datumsgrenze West
An: TRNSYS users mailing list at OneBuilding.org
Cc: hotline
Betreff: Re: [TRNSYS-users] Heating Type Manager (Heating Load is too high)

Hello Asma,

I had a quick look at your .tpf-File and it seems that you are using the Qsens output from the building, converting these in the Equations "Q_sens" and then plotting them, right? The building outputs come in kJ/hr, so in the equation you're only converting them to W, not W/m². I didn't check the project in detail though, so i don't know if that accounts for all of the difference.

I hope this helps, let me know if it is a different problem.

Best,
Christina

________________________________
Von: TRNSYS-users <trnsys-users-bounces at lists.onebuilding.org><mailto:trnsys-users-bounces at lists.onebuilding.org> im Auftrag von Asma Sohail via TRNSYS-users <trnsys-users at lists.onebuilding.org><mailto:trnsys-users at lists.onebuilding.org>
Gesendet: Mittwoch, 25. November 2020 14:15
An: trnsys-users at lists.onebuilding.org<mailto:trnsys-users at lists.onebuilding.org> <trnsys-users at lists.onebuilding.org><mailto:trnsys-users at lists.onebuilding.org>
Cc: Asma Sohail <asma.sohail at hotmail.de><mailto:asma.sohail at hotmail.de>
Betreff: [TRNSYS-users] Heating Type Manager (Heating Load is too high)

Hello trnsys-users,

this is Asma from the University of Stuttgart. Right now I'm working at my diploma thesis using TRNSYS and a problem occured we were not able to solve yet. I hope that you might have a solution or an idea how to fix it. In TRNBuild I'm using the Heating Type Manager with unlimited power to heat a room to a  certain temperature (20°C). I'm only using convective heat. But something is not working properly with the simulation. I get a heating load that is far too high for certain rooms. Specifically, it is about interior rooms with a too high heating load. I've already checked all links or sources of error, but haven't found anything that causes an error. My maximum specific heating load should actually be around 40 W / m² (144 kJ / h per m²), but I get around 100 W/m² (360 kJ/h per m²), although the outside temperature does not fall into the minus range. It would be great if you had an idea
how to fix that or if you could identify the problem. Thank you very much in advance!! I attached the files I used in case you have time to have a look at them.

Thanks and kind regards

Asma

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--
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
3 North Pinckney Street - suite 202
Madison, WI  53703 USA

P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com<mailto:d.bradley at tess-inc.com>

http://www.tess-inc.com
http://www.trnsys.com

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--
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
3 North Pinckney Street - suite 202
Madison, WI  53703 USA

P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com<mailto:d.bradley at tess-inc.com>

http://www.tess-inc.com
http://www.trnsys.com
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