Hi Javed,
You might want to update the "Central Heating Design Supply Air Temperature" in the 'Sizing:System' from 30+C to the lowest reset temperature setpoint defined in setpoint manager.
Your sizing value mismatches with the actual control value. so When reheat coil sees the central design supply air temp is over 30C, it will assume there is no need heat up the supply air at the terminal, therefore, results in 0 heating load.
However, in the actual control (defined in the setpoint manager), the central design supply air temp is between 12-15, which is much lower than 30C. With 0 heating capacity, the reheat coil won't be able to bring the 15 C supply air to 30+C.
You can also hard set the reheat coil capacity (I remember it should be the nominal capacity field?), this will also improve the unmet hours.
Weili
BuildSim.io
On Thursday, March 15, 2018, 2:10:02 PM EDT, Germán Campos ecoeficiente@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx> wrote:
Central heating design supply aire temperature does not affect system design supply airflow but the temperature at the supply outlet which will affect how AHU coils and reheat coils are sized. You should use the maximum temperature from your setpoint manager at the heating coil outlet node. If you are using a reset as per G3.1.3.12 it would be Summer SP-11.1+2.77 (something as 16ºC).
If you set a central heating supply of 32.1 and do the same at zone level, the reheat coil sees the same temperature at its inlet and outlet, resulting in zero capacity.
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Germán Campos
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Germán Campos
Aurea Consulting
www.ecoeficiente.es
www.ecoeficiente.es
2018-03-15 12:32 GMT+01:00 Javed Iqbal eee.javed@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@xxxxxxxxxxxxxxx>:
That is as per G3.1.2.9..1, sized supply-air-to-room-air temperature difference of 20degF (11.1degC) . All the Spaces winter set-point is 21degC so central heating design supply air tempretaire is 32.1 degC.On Thu, Mar 15, 2018 at 4:55 PM, Germán Campos ecoeficiente@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@ yahoogroups.com> wrote:Which are heating design supply temperatures in system and zone sizing?
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Germán CamposAurea Consulting
www.ecoeficiente.es2018-03-15 11:53 GMT+01:00 Javed Iqbal eee.javed@xxxxxxxxx [EnergyPlus_Support] <EnergyPlus_Support@yahoogroup s.com>:Dear All,I assigned a typical VAV system (Baseline System 5) with reheat but there are many heating unmet hours in the zones served by the system. I did most of the quality checks (correct OA, zone setpoints, zone and system sizing etc.) to see where the problem lies. And i found ' AirTerminal:SingleDuct:VAV:Reh eat' is NOT active or sizing is zero in HTML report. To further ascertain the cause of the problem, I plotted temperatures [ see attachment] at all the nodes to see the temperature regime. This also shows that reheat coil doesn't raise the air temperature to meet the room set-point.This is being simulated for CZ5A.I also tried to look out for some solutions discussed here [ LINK LINK ] but unfortunately nothing works for me..I would appreciate any help in this regard..Thank you,--Javed Iqbal, LEED AP, CEASr. Energy Analyst--Javed Iqbal, LEED AP, CEASr. Energy Analyst
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Posted by: Weili Xu <weilix88@xxxxxxxxx>
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