Detailed HVAC and Natural Ventilation

Help and discussion on using the Detailed HVAC option

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gonchotorena
Posts: 4

Detailed HVAC and Natural Ventilation

Postby gonchotorena » Sat Jun 17, 2017 4:04 pm

Good Afternoon.

I am setting a detailed HVAC system with a chiller and heater, with a FAN COIL for the thermal spaces. The problem is if I active natural ventilation and set all the parameters, the heating consumption increase a lot.

I set for heating temperature 22
for cooling temperature 25
for natural ventilation 23

All the elements are ON24/7

How can I say to the heating turn off when I open the windows.

Thank You very much
Luis Sousa
Posts: 340
Location: Stroud

Re: Detailed HVAC and Natural Ventilation

Postby Luis Sousa » Fri Jun 30, 2017 10:41 am

Hi,

The heating is enabled probably due to very cold air introduced by opening the windows. To minimise this effect you can set up the 'Natural ventilation min temperature' to be higher than the Heating setpoint.
Refer to the link below for more infromation:
https://designbuilder.co.uk/helpv5.0/#_ ... omfort.htm

Window modulation can also be used to prevent discomfort due to very cold air being introduced into the zone. Refer to 'Modulation of Openings' for more details: https://designbuilder.co.uk/helpv5.0/#C ... atVent.htm

BR,
Luis
gonchotorena
Posts: 4

Re: Detailed HVAC and Natural Ventilation

Postby gonchotorena » Sun Jul 09, 2017 12:08 pm

Thank you for your answer, but unfortunately it doesn´t get better. As a result I have another question.

Must I set the parameters in the hvvac simple label or in the HVAC detailed scheme?, because the Air Loop AHU has the option to activate mixed mode.

Thank you very much!
Luis Sousa
Posts: 340
Location: Stroud

Re: Detailed HVAC and Natural Ventilation

Postby Luis Sousa » Tue Jul 11, 2017 9:31 am

Hi,

I believe that the online help explains it very well:
"Mixed model data on the HVAC tab is used for a) Simple HVAC and b) zone equipment such as FCU, PTAC etc when using Detailed HVAC. This data is not used to control Detailed HVAC AHUs.
The AHU mixed mode controls are on the Air Handling Unit dialog and any mixed mode settings made on that dialog will override any mixed mode settings made on the HVAC model data tab for zones connected to that AHU."

BR,
Luis

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